JP4441220B2 - Semiconductor light emitting device - Google Patents

Description

  The present invention relates to a semiconductor light emitting device with improved noise characteristics at low output, a manufacturing method thereof, and a driving method thereof.

  FIG. 14 shows a conventional method disclosed in Kuramata et al .: Japanese Journal of Applied Physics 37 (1998) L1373 (A. Kuramata et al., Jpn. J. Appl. Phys. 37 (1998) L1373), etc. 2 shows a refractive index waveguide type semiconductor laser device.

  As shown in FIG. 14, on a substrate 101 made of sapphire, for example, an n-type semiconductor unit 102, an active layer 103, and a p-type contact layer each made of a III-V compound semiconductor and including an n-type contact layer. A p-type semiconductor portion 104 containing is formed by crystal growth.

  An upper portion of the p-type contact layer in the p-type semiconductor portion 104 has a ridge portion patterned in a stripe shape, and a p-side electrode 105 is formed on the entire surface of the ridge portion. Here, the region below the p-side electrode 105 in the active layer 103 is a resonator that causes laser oscillation.

  In the n-type contact layer of the n-type semiconductor portion 102, one side region of the p-side electrode 105 is exposed, and the n-side electrode 106 is formed on the entire exposed surface.

  When a drive current flows in the forward direction from the p-side electrode 105 toward the n-side electrode 106 and the value of the drive current exceeds a predetermined oscillation threshold current value, laser light is emitted from one end face of the active layer 103. .

  When a violet laser beam is used when performing a writing operation on an optical disk apparatus, for example, a high-density digital versatile (video) disk (HD-DVD) apparatus, using the semiconductor laser element as shown in FIG. An output value of 30 mW or more is required. Conversely, the output value of the violet laser beam during the reading operation needs to be as small as about 1 mW.

  However, during the read operation, the conventional semiconductor laser device has a problem that the relative noise intensity increases as the output value decreases even if a high frequency is superimposed on the drive current. This is because the relative noise intensity is increased by the influence of the relaxation oscillation of the laser oscillation because the laser oscillation is performed with an injection current value substantially equal to the oscillation threshold value.

  In addition, since the oscillation is performed with an injection current value approximately equal to the threshold current of laser oscillation, the single mode property is lowered, and the multimode component is generated, thereby increasing the relative noise intensity.

  In order to reduce the relative noise intensity, it is necessary to increase the relaxation oscillation frequency. One way to do this is to increase the differential gain. In order to increase the differential gain of laser oscillation, the oscillation threshold may be increased by forming a light absorption region.

  As another method, the operating current value may be set to be larger than the oscillation threshold value by decreasing the slope efficiency (differential efficiency) and increasing the current value necessary for the laser output of about 1 mW. .

  Note that the noise of the semiconductor laser element can be reduced by increasing the reflectance of the cavity end face. In this case, however, the output (light output) value of the laser light also decreases. Therefore, as described above, when the HD-DVD device performs a writing operation, a high output light emission is required, and therefore, a measure is taken to increase the end face reflectance so that the light output value decreases. It is not possible.

  Further, when self-excited oscillation is caused in the semiconductor laser element, it is necessary to provide a light absorption layer made of a semiconductor in the active layer 103 or in the vicinity thereof. However, when such a light absorption layer is provided in the semiconductor laser device itself, there is a problem that it is difficult to obtain a high output value.

  An object of the present invention is to solve the above-described conventional problems and to realize a semiconductor light emitting device having a small relative noise intensity even at a low output.

  In order to achieve the above object, the present invention divides the p-side electrode or the n-side electrode and applies a driving current only to a part of the divided electrodes at the time of reading that requires a low output operation. .

  Specifically, a semiconductor light emitting device according to the present invention includes a first semiconductor layer of a first conductivity type formed in a substantially uniform thickness on a substrate, and a substantially uniform on the first semiconductor layer. A second conductivity type second semiconductor layer formed in a film thickness, and an active layer formed in a substantially uniform film thickness between the first semiconductor layer and the second semiconductor layer and generating emitted light A first electrode that supplies a driving current to the first semiconductor layer, and a second electrode that supplies a driving current to the second semiconductor layer, and the first electrode or the second electrode is mutually connected It is a divided electrode composed of a plurality of conductive members spaced from each other.

  According to the semiconductor light emitting device of the present invention, the first semiconductor layer and the second semiconductor layer sandwiching the active layer, the first electrode for supplying a driving current to the first semiconductor layer, and the second semiconductor layer are driven. A second electrode for supplying a current, and the first electrode or the second electrode is a divided electrode made of a plurality of conductive members spaced from each other. For this reason, a drive current is applied to all the divided electrodes during a high output operation. On the other hand, at the time of low output operation, a drive current is applied to a part of the divided electrodes, and a drive current is non-uniformly injected into the active layer, thereby forming a light absorption region in the active layer. As a result, the oscillation threshold current value is increased, the differential gain of laser oscillation is increased, and the relative noise intensity at the time of low output can be reduced.

  In the semiconductor light emitting device of the present invention, it is preferable that the divided electrode is provided on the main surface side on which the active layer is formed on the substrate.

  In the semiconductor light emitting device of the present invention, the second electrode has a stripe pattern that forms a resonator in the active layer, and the divided electrode is divided so as to separate the emission end face side and the reflection end face side in the resonator. Preferably it is.

  In the semiconductor light emitting device of the present invention, it is preferable that the first electrode and the second electrode are provided on the main surface side on which the active layer is formed on the substrate.

  In the semiconductor light emitting device of the present invention, the divided electrode is preferably a p-side electrode that injects holes into the active layer.

  In this case, it is preferable that the p-side electrode has a stripe pattern formed on the second semiconductor layer, and the interval between the plurality of conductive members in the p-side electrode is about 10 μm or less.

  In the semiconductor light emitting device of the present invention, the divided electrode is preferably an n-side electrode that injects electrons into the active layer.

  In this case, the n-side electrode is formed on a region exposed to one side of the p-side electrode in the first semiconductor layer, and the interval between the plurality of conductive members in the n-side electrode is about 5 μm or more. Preferably there is.

  In this case, the second electrode is a p-side electrode having a stripe pattern formed on the second semiconductor layer, and the n-side electrode is one side of the p-side electrode in the first semiconductor layer. The divided region formed between the first electrode portion and the second electrode portion is formed in a direction in which the p-side electrode extends. It is preferable that the tilt angle is larger than 0 ° and smaller than 90 ° with respect to a direction perpendicular to the substrate surface.

  In this case, the second electrode is a p-side electrode having a stripe pattern formed on the second semiconductor layer, and the first semiconductor layer is exposed on both sides of the p-side electrode, An n-side electrode is formed on a region on one side of the p-side electrode in the first semiconductor layer and on a region on the other side of the p-side electrode in the first semiconductor layer. It is preferable that the first electrode portion and the second electrode portion are formed so that each planar shape is asymmetric with respect to the p-side electrode.

  In the semiconductor light emitting device of the present invention, the substrate has conductivity, and the divided electrode is provided on the surface of the substrate opposite to the main surface on which the active layer is formed, and the substrate It is preferable that it is comprised from the 2nd electrode part provided in the main surface side in which the active layer in is formed.

  In this case, the divided electrode is an n-side electrode, the first electrode portion is provided on almost the entire surface on the side opposite to the main surface of the substrate, and the second electrode portion is formed in a region on the side of the p-side electrode. It is preferable that the second electrode is a p-side electrode having a stripe pattern formed on the second semiconductor layer.

  In the semiconductor light emitting device of the present invention, the active layer is preferably made of a compound semiconductor containing nitrogen in its composition.

  In the semiconductor light emitting device of the present invention, the active layer is preferably made of a compound semiconductor containing phosphorus in its composition.

  In the first method for manufacturing a semiconductor light emitting device according to the present invention, a first conductive type first semiconductor layer, an active layer, and a second conductive type second semiconductor layer are substantially uniform on a substrate. A step of sequentially growing the film thickness, a step of exposing a part of the first semiconductor layer, and then forming a first electrode on the exposed first semiconductor layer; A step of forming a second electrode, and a step of forming a split electrode by insulatingly separating the first electrode or the second electrode into a plurality of electrodes.

  According to the first method for manufacturing a semiconductor light emitting device, a first electrode for supplying a driving current to the first semiconductor layer and a second electrode for supplying a driving current to the second semiconductor layer are formed, and then The divided electrode is formed by insulating and separating the first electrode or the second electrode into a plurality of electrodes. For this reason, the semiconductor light-emitting device of this invention can be obtained reliably.

  In the first method for manufacturing a semiconductor light emitting device, it is preferable to use an etching method for forming the divided electrodes.

  In the first method for manufacturing a semiconductor light emitting device, it is preferable to use a lift-off method for forming the divided electrodes.

  In the second method for manufacturing a semiconductor light emitting device according to the present invention, the first conductive type first semiconductor layer, the active layer, and the second conductive type second semiconductor layer are substantially uniform on the substrate. Forming a first n-side electrode on the exposed first semiconductor layer after exposing a part of the first semiconductor layer, and an active layer in the substrate; The method includes a step of forming a second n-side electrode on the opposite surface and a step of forming a p-side electrode on the second semiconductor layer.

  According to the second method for manufacturing a semiconductor light emitting device, the n-side electrode is formed on the first n-side electrode on the first semiconductor layer and the second n-side electrode on the surface of the substrate opposite to the active layer. Therefore, the n-side electrode becomes a split electrode. Thereby, the semiconductor light-emitting device of this invention can be obtained reliably.

  In the first or second method for manufacturing a semiconductor light emitting device, the active layer is preferably made of a compound semiconductor containing nitrogen in its composition.

  In the first or second method for manufacturing a semiconductor light emitting device, the active layer is preferably made of a compound semiconductor containing phosphorus in its composition.

  A first semiconductor light emitting device driving method according to the present invention includes a first conductivity type first semiconductor layer formed on a substrate and a second conductivity type second semiconductor layer formed on the first semiconductor layer. Two semiconductor layers, an active layer that is formed between the first semiconductor layer and the second semiconductor layer and generates emission light, a first electrode that supplies a driving current to the first semiconductor layer, And a second electrode having a stripe shape for supplying a driving current to the second semiconductor layer, and the semiconductor light emission using the first electrode or the second electrode as a divided electrode divided in a direction in which the second electrode extends In the case of the device, the split electrode is composed of a first electrode part located on the emission end face side and a second electrode part located on the reflection end face side, and when the oscillation output value of the laser light is relatively large, A first drive current is applied to the first electrode portion and the second electrode portion, and the oscillation output value of the laser beam is compared with each other. In the case where the first drive current is reduced, the first drive current is applied to the first electrode portion, and the second drive current having a value smaller than the first drive current is applied to the second electrode portion, or the Whether the second drive current is not applied, or the first drive current is applied to the second electrode portion and the second drive current having a value smaller than the first drive current is applied to the first electrode portion Alternatively, the second drive current is not applied.

  According to the driving method of the first semiconductor light emitting device, when relatively increasing the oscillation output value of the laser beam, the first driving current is applied to the first electrode portion and the second electrode portion of the divided electrode. When the oscillation output value of the laser beam is made relatively small, the first drive current is applied to the first electrode part (or the second electrode part) and the second electrode part (or the first electrode). A second drive current having a value smaller than that of the first drive current is applied to the part), or the second drive current is not applied. As a result, a current can be injected non-uniformly into the active layer during a low output operation, so that a light absorption region is formed in the active layer. As a result, since the value of the oscillation threshold current increases, the differential gain of laser oscillation increases, and the relative noise intensity at low output can be reduced.

  A second semiconductor light emitting device driving method according to the present invention includes a first conductivity type first semiconductor layer formed on a substrate and a second conductivity type second semiconductor layer formed on the first semiconductor layer. Two semiconductor layers, an active layer that is formed between the first semiconductor layer and the second semiconductor layer and generates emission light, a first electrode that supplies a driving current to the first semiconductor layer, And a second electrode having a stripe shape for supplying a driving current to the second semiconductor layer, and driving the semiconductor light emitting device using the first electrode or the second electrode as a divided electrode divided in the front-back direction of the substrate For the method, the divided electrode is provided on the side of the emission end face or the reflection end face on the first electrode portion provided so as to cover almost the entire surface of the substrate opposite to the active layer. When the oscillation output value of the laser beam is relatively large When the first drive current is applied to the first electrode portion and the oscillation output value of the laser beam is relatively small, the first drive portion has a value smaller than the first drive current. Two drive currents are applied, or the second drive current is not applied, and the first drive current is applied to the second electrode portion.

  According to the control method of the second semiconductor light emitting device, when the oscillation output value of the laser beam is relatively small, the second drive current having a value smaller than the first drive current is applied to the first electrode portion. Alternatively, the first drive current is applied to the second electrode portion without applying the second drive current. For this reason, since a current can be injected non-uniformly into the active layer during a low output operation, a light absorption region is formed in the active layer. As a result, since the value of the oscillation threshold current increases, the differential gain of laser oscillation increases, and the relative noise intensity at low output can be reduced.

  In the driving method of the first or second semiconductor light emitting device, the second driving current is preferably generated by passing the first driving current through the resistance variable means.

  In the driving method of the first or second semiconductor light emitting device, it is preferable that the peak value of the second driving current is approximately half or less than the peak value of the first driving current.

  A third semiconductor light emitting device driving method according to the present invention includes a first conductivity type first semiconductor layer formed on a substrate and a second conductivity type second semiconductor layer formed on the first semiconductor layer. Two semiconductor layers, an active layer that is formed between the first semiconductor layer and the second semiconductor layer and generates emission light, a first electrode that supplies a driving current to the first semiconductor layer, And a second electrode having a stripe shape for supplying a driving current to the second semiconductor layer, and the semiconductor light emission using the first electrode or the second electrode as a divided electrode divided in a direction in which the second electrode extends For the apparatus, the divided electrode is composed of a first electrode part located on the emission end face side and a second electrode part located on the reflection end face side, and is mutually valued with respect to the first electrode part and the second electrode part. Are applied so that self-oscillation occurs.

  According to the driving method of the third semiconductor light emitting device, since the driving currents having different values are applied to the first electrode portion and the second electrode portion of the divided electrode so that self-excited oscillation occurs, a high frequency signal is applied. Since the relative noise intensity is reduced without superimposing, the driving circuit in the laser element can be simplified.

  In the third method for driving a semiconductor light emitting device, it is preferable not to apply a driving current to one of the first electrode portion and the second electrode portion during self-excited oscillation.

  The fourth method for driving a semiconductor light emitting device according to the present invention reads the recorded information recorded on the recording medium using the reflected light of the laser light emitted from the semiconductor light emitting device having a resonator that oscillates the laser light. The driving method of the semiconductor light emitting device is targeted, and when reading recorded information, a driving current is injected non-uniformly into the resonator.

  According to the fourth method for driving a semiconductor light emitting device, a current absorption region is formed in the active layer because current is injected non-uniformly into the active layer. As a result, since the value of the oscillation threshold current increases, the differential gain of laser oscillation increases, and the relative noise intensity at low output can be reduced.

  In the fourth method for driving a semiconductor light emitting device, it is preferable that the semiconductor light emitting device self-oscillates.

  In the fourth method for driving a semiconductor light emitting device, the drive current is preferably a high frequency current.

  In this case, the frequency of the high frequency current is preferably about 100 MHz or more.

  In the conventional semiconductor light emitting device, there are laser elements with divided electrodes, such as integrated laser elements such as Bragg reflector (DBR) laser elements, but the elements corresponding to the divided electrodes are They have different functions, and the crystal structure and the like in the light emitting region are different for each electrode.

  In addition, when a modulation current is applied to a conventional laser element with electrodes separated, currents having different intensities, frequencies or phases are applied. Furthermore, although a laser structure in which an n-side electrode is provided on both sides of a p-side electrode is known, the length of the resonator in the resonance direction of the n-side electrode is the same.

  According to the semiconductor light emitting device and the driving method thereof according to the present invention, since the divided electrode formed by dividing the p-side electrode or the n-side electrode is provided, a driving current is applied to a part of the divided electrode. Then, by injecting the drive current non-uniformly into the active layer, the oscillation threshold value is increased, so that the relative noise intensity at the time of low output can be reduced.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a semiconductor laser device according to the first embodiment of the present invention.

  As shown in FIG. 1, an n-type semiconductor portion 12, an active layer (light emitting layer) 13, and a p-type semiconductor portion 14 are formed on a main surface of a semiconductor substrate 11 made of, for example, gallium nitride (GaN). And an epitaxial growth method such as a metal organic chemical vapor deposition (MOVPE) method.

  The n-type semiconductor unit 12 includes an n-type contact layer made of n-type gallium nitride (GaN), an n-type cladding layer made of n-type aluminum gallium nitride (AlGaN), and an n-type gallium nitride (GaN) from the semiconductor substrate 11 side. And an n-type guide layer. A buffer layer made of gallium nitride (GaN) may be provided in the lowermost layer of the n-type semiconductor unit 12.

  The p-type semiconductor unit 14 includes, from the active layer 13 side, a p-type guide layer made of p-type gallium nitride (GaN), a p-type cladding layer made of p-type aluminum gallium nitride (AlGaN), and p-type gallium nitride (GaN). A p-type contact layer is included.

  The active layer 13 uses a group III-V nitride semiconductor having an energy gap smaller than that of the n-type guide layer and the p-type guide layer, such as indium gallium nitride (InGaN). The active layer 13 may have a multiple quantum well structure.

  On the p-type semiconductor portion 14, for example, a p-side electrode 15 made of a laminate of nickel (Ni) and gold (Au) and having a stripe shape with a width of about 1.8 μm to 2.5 μm is formed. Yes. The p-side electrode 15 is a divided electrode that is divided by etching, for example, with the emission end face 13a side of the active layer 13 as the first electrode part 15a and the reflection end face 13b side as the second electrode part 15b.

  The side portion of the p-side electrode 15 in the p-type contact layer of the p-type semiconductor portion 14 is reduced in thickness by etching to form a waveguide (resonator) in the active layer 13. Therefore, the region between the first electrode portion 15a and the second electrode portion 15b in the p-type contact layer is not etched.

  The distance between the first electrode portion 15a and the second electrode portion 15b of the p-side electrode 15 is about 1 μm. In addition, the length of the second electrode portion 15b is adjusted so that the threshold current of the laser light is, for example, about 100 mA so that the threshold current of the laser light is 2 to 3 times that in the high output operation. Here, when the length of the waveguide is about 0.5 mm, the length of the second electrode portion 15b may be about 0.1 mm.

  An n-side electrode 16 made of a laminate of, for example, titanium (Ti) and aluminum (Al) is formed on the surface (back surface) opposite to the main surface on which the active layer 13 is formed in the semiconductor substrate 11. Yes.

  The active layer 13 has a substantially uniform film thickness in the entire region of the waveguide. Since a nitride semiconductor has a large differential gain, if the film thickness of the active layer 13 is not uniform, a light emission light obtained when a high output operation is performed by injecting current into the p-side electrode 15 and the n-side electrode 16. Becomes non-uniform. As a result, the desired light emission intensity cannot be obtained, and the film thickness of the active layer 13 needs to be uniform.

  Also in the n-type semiconductor portion 12 and the p-type semiconductor portion 14, the film thickness of each semiconductor layer included in these is substantially uniform in the direction in which the waveguide extends (outgoing direction). In particular, in the case of a nitride semiconductor, since the resistance value of the p-type semiconductor is large, if the film thickness of the p-type semiconductor portion 14 is non-uniform in the emission direction, the injection of drive current becomes non-uniform. As a result, when a high output operation is performed by injecting current into the p-side electrode 15 and the n-side electrode 16, a desired light output cannot be sufficiently obtained. In order to avoid this, the film thickness of each semiconductor layer constituting the n-type semiconductor portion 12 and the p-type semiconductor portion 14 is substantially uniform in the emission direction.

  Incidentally, as described above, the distance between the first electrode portion 15a and the second electrode portion 15b of the p-side electrode 15 is about 1 μm. When this interval is increased to 10 μm or more, even if a drive current is simultaneously injected into the first electrode portion 15a and the second electrode portion 15b in a high output operation, the drive current is not injected into the active layer 13 As a result, a desired laser oscillation characteristic cannot be obtained. Therefore, it is preferable that the distance between the first electrode portion 15a and the second electrode portion 15b is small in a range in which a large current does not flow.

  As described above, the region between the first electrode portion 15a and the second electrode portion 15b of the p-type contact layer is left without being removed. This is because when the drive current is injected into both the first electrode portion 15a and the second electrode portion 15b, the lower region of the active layer 13 between the first electrode portion 15a and the second electrode portion 15 is not. This is to prevent the light emitting region from being formed.

  Hereinafter, the operation of the semiconductor laser device configured as described above will be described with reference to the drawings.

(First driving method)
First, a driving method of a high output operation corresponding to the writing operation when the semiconductor laser element is used in, for example, a pickup unit in an HD-DVD device will be described. As shown in FIG. 2A, a pulsed drive current is applied to the first electrode portion 15a and the second electrode portion 15b of the p-side electrode 15 and the n-side electrode 16 during high output operation. As a result, the drive current is almost uniformly injected into the active layer 13.

  Next, a driving method of a low output operation corresponding to a read operation in the HD-DVD device will be described. As shown in FIG. 2 (b), during a low output operation, a pulsed drive current in which a high-frequency signal is superimposed is applied to the first electrode portion 15 a and the n-side electrode 16 of the p-side electrode 15 by the signal source 20. Apply. That is, no drive current is applied to the second electrode portion 15 b of the p-side electrode 15. Here, the frequency of the high-frequency signal to be superimposed is preferably 100 MHz or more, and this is the same in other embodiments.

  By such non-uniform current injection into the active layer 13, only the lower portion of the first electrode portion 15a in the active layer 13 emits light, while the lower portion of the second electrode portion 15b in the active layer 13 is a light absorption region. Function as. By forming this light absorption region, the multi-mode spectral line width is widened like the super luminescence diode element, and as a result, the coherence of the emitted light is reduced and the noise can be reduced.

  In the first embodiment, a III-V group nitride semiconductor having an oscillation wavelength of about 400 nm is used as the semiconductor crystal. However, the present invention is not limited to this, and indium gallium phosphide (InGaP) having an oscillation wavelength of about 670 nm is used. Such III-V phosphide semiconductors may be used.

  However, a laser device using a nitride semiconductor has various preferable features as described below.

  That is, since the resistivity of the p-type crystal in the nitride semiconductor is large, the injection current can be activated only by dividing the p-side electrode 15 without isolating the p-type semiconductor portion 14 such as the p-type contact layer. The layer 13 can be injected non-uniformly in a direction perpendicular to the substrate surface.

  Furthermore, phosphide semiconductors or arsenide semiconductor crystals have a zinc blende type crystal structure, whereas nitride semiconductor crystals have a hexagonal crystal structure, so that they are perpendicular to the direction parallel to the main surface of the substrate. Electrical directions differ from each other. For example, the carrier mobility is smaller in the direction parallel to the direction perpendicular to the main surface of the substrate. As a result, in the case of a nitride semiconductor crystal, since it becomes difficult for current to flow between the first electrode portion 15a and the second electrode portion 15b, which are divided electrodes, the effect of performing electrode division is great.

  In addition, a gallium nitride (GaN) -based compound semiconductor has an extremely large differential gain compared to a compound semiconductor containing indium phosphide (InP) or gallium arsenide (GaAs) as a main component. This is because gallium nitride belongs to the hexagonal system and holes are not degenerated. Thus, since the gallium nitride compound semiconductor has a large differential gain, if the current distribution is slightly biased, whether the crystal has gain or loss changes. As a result, in a laser device using a gallium nitride-based compound semiconductor, a change in the light density distribution in the waveguide can be effectively induced by injecting a drive current even slightly evenly into the active layer 13. Can do.

(Second driving method)
Next, a second driving method of the semiconductor laser element according to the first embodiment of the present invention will be described.

  As shown in FIG. 3, a variable resistor 21 is connected between the second electrode portion 15b of the p-side electrode 15 and the signal source 20, and a pulsed drive current in which a high frequency signal is superimposed from the signal source 20 is This is applied to the first electrode portion 15 a and the second electrode 15 b of the p-side electrode 15 and the n-side electrode 16.

  At the time of high output operation, the resistance value of the variable resistor 21 is set to almost zero, and at the time of low output operation, the resistance value of the variable resistor 21 is set to a finite value. As a result, a drive current is uniformly injected into the active layer 13 during a high output operation, and a drive current is injected non-uniformly into the active layer 13 during a low output operation. Thus, by adjusting the resistance value of the variable resistor 21 for the amount of drive current applied to the second electrode portion 15b, the absorption amount of the emitted light in the active layer 13 can be adjusted.

  That is, the second electrode portion 15b is formed to an appropriate length, and then the resistance value of the variable resistor 21 is adjusted to change the laser oscillation threshold current, thereby making it possible to reduce the relative intensity noise during the low output operation. Can be reduced.

  In addition, it is preferable that the value of the drive current applied to the second electrode portion 15b during the low output operation is about half or less of the value of the drive current applied to the first electrode portion 15a.

  Further, the first driving method in which the driving current is not applied to the second electrode portion 15b corresponds to setting the resistance value of the variable resistor 21 to infinity in the second driving method.

  In the first embodiment, the variable resistor 21 is connected between the signal source 20 and the second electrode unit 15b. Instead, the variable resistor 21 is connected between the signal source 20 and the first electrode unit 15a. You may connect.

  Further, the means for reducing the drive current amount for the second electrode portion 15b of the p-side electrode 15 is the variable resistor 21, but it is not limited to this, and the element or circuit configuration has the same function as the variable resistor 21. May be.

  Also, the amount of emitted light absorbed in the active layer 13 can be adjusted by applying a bias current to the DC signal.

(Third driving method)
Next, a third driving method of the semiconductor laser element according to the first embodiment of the present invention will be described.

  As shown in FIG. 4, in the third driving method, instead of applying a driving current to the first electrode portion 15a, a driving current superimposed with a high-frequency signal is applied to the second electrode portion 15b. Thereby, since the output intensity of the emitted light on the emission end face 13a side in the active layer 13 is lowered, the deterioration of the emission end face 13a can be suppressed.

  In addition, since the intensity of the emitted light is increased at the reflection end face 13b, the laser oscillation mode is stabilized.

  Further, unlike the indium gallium phosphide-based red semiconductor laser device, the gallium nitride-based blue semiconductor laser device has a transparent substrate, so that scattered light from the substrate is mixed with the emitted light and noise tends to increase. As in the third driving method, a scattered current from the substrate is reduced by applying a driving current to the second electrode portion 15b away from the emission end face 13a side to reduce the injection current on the emission end face 13a side. be able to. As a result, the scattered light from the substrate is less likely to be mixed into the outgoing light, and noise can be reduced.

(Fourth driving method)
Next, a fourth driving method of the semiconductor laser element according to the first embodiment of the present invention will be described.

  In the active layer 13, the first resistance value of the lower part of the second electrode portion 15b that becomes the light absorption layer is Rv, and the second resistance value of the region between the first electrode portion 15a and the second electrode portion 15b is used. Is Rs and the element capacitance is C, the resonance frequency f of the laser element is expressed by the following equation (1).

f = 2π / {(Rv + Rs) C} ^1/2 (1)
For example, when the interval between the first electrode portion 15a and the second electrode portion 15b is 1 μm, the second resistance value Rs is 15Ω, and the length of the second electrode portion 15b is 0.1 mm. Since the element capacitance C is 0.8 fF, the first resistance value Rv is set to 20Ω, and a drive current is applied to the second electrode portion 15b and the n-side electrode 16 of the p-side electrode 15 to thereby generate a resonance frequency f. A self-oscillation phenomenon occurs at 37 MHz.

  When the self-excited oscillation phenomenon occurs, the relative noise intensity is reduced without superimposing the high-frequency signal on the drive current, so that the laser element drive circuit can be simplified.

  By performing this self-excited oscillation operation, it has been confirmed that the relative noise intensity when the optical output is 1 mW is reduced to −135 dB / Hz to −110 dB / Hz or less.

  Note that a conventional semiconductor laser element that generates self-excited oscillation has a crystal layer that absorbs light in a region where light is distributed, and the drive current is not injected nonuniformly as in this embodiment.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

  FIG. 5A to FIG. 5C show the order of steps in the method of manufacturing a semiconductor laser device according to the second embodiment of the present invention.

  First, as shown in the cross-sectional view of FIG. 5A, an n-type semiconductor portion 12, an active layer 13, and a p-type semiconductor portion 14 are sequentially grown on a substrate 31 made of sapphire, for example, by MOVPE. Here, the n-type semiconductor portion 12 is formed by sequentially forming an n-type contact layer made of n-type gallium nitride (GaN), an n-type clad layer made of n-type aluminum gallium nitride (AlGaN), and an n-type. An n-type guide layer made of gallium nitride (GaN) is included. The p-type semiconductor unit 14 is formed by sequentially forming a p-type guide layer made of p-type gallium nitride (GaN), a p-type cladding layer made of p-type aluminum gallium nitride (AlGaN), and p-type nitride. A p-type contact layer made of gallium (GaN) is included.

  For the active layer 13, for example, indium gallium nitride (InGaN) or aluminum gallium nitride (AlGaN) whose aluminum composition is smaller than each cladding layer is used. Subsequently, a first metal film made of a laminate of nickel (Ni) and gold (Au) and having a thickness of about 100 nm or less is deposited on the entire surface of the p-type semiconductor portion 14 by, for example, vapor deposition.

  Next, as shown in a cross-sectional view in a direction parallel to the waveguide (resonator) formation region in FIG. 5B, a width of about 1 μm is formed on the first metal film deposited by photolithography. In addition, a p-side electrode forming resist pattern 40 having an opening 40a in a direction substantially perpendicular to the waveguide forming region is formed. Thereafter, dry etching using an etching gas containing chlorine is performed on the first metal film using the formed resist pattern 40 as a mask, so that the first electrode portion 15a and the second electrode portion are formed from the first metal film. A p-side electrode 15 made of 15b is formed.

  Next, as shown in the plan view and the left side view of FIG. 5C, the p-type semiconductor portion 12 is subjected to dry etching using an etching gas containing chlorine in the regions on both sides of the p-side electrode 15. A waveguide having a stripe shape is formed by exposing the p-type guide layer. Subsequently, the n-type contact layer of the n-type semiconductor portion 14 is exposed in a region on one side of the p-side electrode 15 by dry etching using an etching gas containing chlorine. Subsequently, a second metal film made of a laminate of titanium (Ti) and aluminum (Al) is deposited by an evaporation method, and the deposited second metal film is patterned, and the second metal film is patterned. An n-side electrode 16 is formed.

  As described above, in the second embodiment, since the interval between the first electrode portion 15a and the second electrode portion 15b of the p-side electrode 15 that is the divided electrode needs to be relatively small, about 1 μm, etching becomes easy. As described above, the thickness of the p-side electrode 15 is set to 100 nm or less. Therefore, when mounting the semiconductor laser device according to the second embodiment on the mount member, in order to suppress deterioration of the p-side electrode 15 due to the solder material, gold plating having a thickness of about 10 μm is applied on the p-side electrode 15. Thus, the p-side electrode 15 and the solder material are prevented from coming into direct contact.

  In the second embodiment, the insulating substrate 31 is used as the substrate. However, when a conductive substrate is used as in the first embodiment, the n-side electrode 16 is placed on the back surface of the substrate. What is necessary is just to provide.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

  FIGS. 6A and 6B schematically show a semiconductor laser device and a driving method thereof according to the third embodiment of the present invention. 6 (a) and 6 (b), the same components as those shown in FIG.

  As shown in FIG. 6A, the semiconductor laser device according to the third embodiment uses an insulating substrate 31 made of, for example, sapphire. On the main surface of the substrate 31, the n-type semiconductor portion 12, the active layer (light emitting layer) 13, and the p-type semiconductor portion 14 are formed by the MOVPE method, as in the first embodiment.

  In the third embodiment, the p-side electrode 15 having a stripe shape is not divided. Instead, one region of the p-side electrode 15 in the n-type semiconductor portion 12 is etched to expose the n-type contact layer, the n-side electrode 16 is formed in the exposed region, and the n-side electrode 16 is used as a divided electrode. Yes.

  That is, the n-side electrode 16 is a divided electrode in which the emission end face 13a side of the active layer 13 is the first electrode portion 16a and the reflection end face 13b side is the second electrode portion 16b.

  Since the resistance value of the n-type semiconductor part 12 is smaller than that of the p-type semiconductor layer part 14, if the n-side electrode 16 is divided instead of dividing the p-side electrode 15, the first electrode part 16a and the second electrode part 16b The drive current can be uniformly injected into the active layer 13 even if the distance between the active layer 13 and the active layer 13 is increased. Therefore, unlike the first electrode portion 15a and the second electrode portion 15b of the p-side electrode 15 according to the first embodiment, it is not necessary to set the distance between the electrode portions 15a and 15b to an extremely small value of 1 μm. . This makes it difficult for optical and electrical characteristics of the laser element to deteriorate and facilitates the processing of the divided electrodes.

  Here, the resistivity of the n-type contact layer in the n-type semiconductor layer 12 is 0.015 Ωcm, the distance between the first electrode portion 16a and the second electrode portion 16b is d (μm), and the first electrode portion 16a and the first electrode portion The voltage drop V between the two electrode portions 16a and 16b when the injection current to one of the two electrode portions 16b is I (A) is expressed by the following equation (2).

V = 0.6 I · d (2)
This is because an appropriate voltage drop is generated between the electrode portions 16a and 16b because the thickness of the n-type semiconductor portion 12 is as small as about 2 μm. Therefore, for example, when the injected current value is 100 mA and the distance between the electrode portions 16a and 16b is 1 μm, the value of the voltage drop V is 0.06V, and this value is sufficient to operate at a low output. It is not the amount of descent.

  Therefore, when the interval between the first electrode portion 16a and the second electrode portion 16b of the n-side electrode is 5 μm, the value of the voltage drop V becomes 0.3V, and the current flowing through the region between the electrode portions 16a and 16b is limited. it can. As a result, drive current can be injected non-uniformly into the active layer 13 in a direction perpendicular to the substrate surface.

  Furthermore, it is preferable that the interval between the first electrode portion 16a and the second electrode portion 16b is set to 10 μm or more, and the value of the voltage drop V is set to 0.6V or more. When current is not injected into one of the first electrode portion 16a and the second electrode portion 16b, the distance between the electrode portions 16a and 16b is set to 20 μm or more, and the value of the voltage drop V is set to 1.2V or more. It is necessary to secure it.

  Hereinafter, the operation of the semiconductor laser device configured as described above will be described with reference to the drawings.

  First, a driving method at the time of high output operation of the semiconductor laser element will be described. As shown in FIG. 6A, a pulsed drive current is applied to the first electrode portion 16a and the second electrode portion 16b of the p-side electrode 15 and the n-side electrode 16 during high output operation. As a result, the drive current is almost uniformly injected into the active layer.

  On the other hand, as shown in FIG. 6B, during low output operation, a variable resistor 21 is connected between the second electrode portion 16 b of the n-side electrode 16 and the signal source 20, and a high frequency signal is transmitted from the signal source 20. Is applied to the first electrode portion 16 a and the second electrode 16 b of the p-side electrode 15 and the n-side electrode 16. At this time, the resistance value of the variable resistor 21 is set to a finite value, and the second drive current having a smaller amplitude than the first drive current applied to the first electrode portion 16a is applied to the second electrode portion 16b. . However, the current amount of the second drive current may be set to almost zero according to the output intensity of the laser beam.

  The configuration shown in FIG. 6A corresponds to the case where the resistance value of the variable resistor 21 is 0 in FIG.

  With this configuration, as in the first embodiment, the relative noise intensity during the low output operation can be reduced.

  In the third embodiment, the variable resistor 21 may be connected between the signal source 20 and the first electrode portion 16a.

  Further, although the variable resistor 21 is provided between the second electrode portion 16b of the n-side electrode 16 and the signal source 20, an element or a circuit configuration having the same function as the variable resistor 21 may be used. Further, the amount of light absorbed in the active layer 13 can be adjusted by applying a bias current to the DC signal instead of using the AC signal as the drive current.

  Further, the third driving method shown in the first embodiment in which a driving current is applied to the second electrode portion 16b instead of the first electrode portion 16a during the low output operation may be used.

  Furthermore, the self-oscillation operation may be performed by using the fourth driving method shown in the first embodiment.

(Production method)
Hereinafter, a method for manufacturing the semiconductor laser device configured as described above will be described with reference to the drawings.

  FIG. 7A to FIG. 7E show the order of steps in the method of manufacturing a semiconductor laser device according to the third embodiment of the present invention.

  First, as shown in the sectional view of FIG. 7A, an n-type semiconductor portion 12, an active layer 13, and a p-type semiconductor portion 14 are sequentially grown on a substrate 31 made of sapphire, for example, by MOVPE. Here, the n-type semiconductor portion 12 is formed by sequentially forming an n-type contact layer made of n-type gallium nitride (GaN), an n-type clad layer made of n-type aluminum gallium nitride (AlGaN), and an n-type. An n-type guide layer made of gallium nitride (GaN) is included. The p-type semiconductor unit 14 is formed by sequentially forming a p-type guide layer made of p-type gallium nitride (GaN), a p-type cladding layer made of p-type aluminum gallium nitride (AlGaN), and p-type nitride. A p-type contact layer made of gallium (GaN) is included.

  For the active layer 13, for example, indium gallium nitride (InGaN) or aluminum gallium nitride (AlGaN) whose aluminum composition is smaller than each cladding layer is used.

  Next, as shown in the plan view of FIG. 7B, the n-type contact layer of the n-type semiconductor portion 12 is exposed along the waveguide formation region by dry etching using an etching gas containing chlorine.

  Next, as shown in the plan view and the left side view of FIG. 7C, nickel (Ni) and gold (gold) are formed in the waveguide formation region on the p-type semiconductor portion 14 by using, for example, a vapor deposition method and an etching method. A p-side electrode 15 having a width of about 1.8 μm to 2.5 μm is formed. In this case, the first metal film for forming the p-side electrode is deposited after the etching process for exposing the n-type contact layer. Instead, the first metal film for forming the p-side electrode is used instead. After the deposition, patterning of the p-side electrode 15 and etching for exposing the n-type contact layer may be sequentially performed.

  Next, as shown in the plan view of FIG. 7D, the first end 41a is provided on the reflection end face 13a side on the exposed region of the n-type semiconductor portion 12 by photolithography, and the emission end face is formed. A resist pattern 41 for forming an n-side electrode having a second opening 41b on the 13b side is formed.

  Next, as shown in the plan view of FIG. 7E, a second metal film made of a laminate of titanium (Ti) and aluminum (Al) is deposited on the resist pattern 41 by, for example, vapor deposition. Then, by lifting off the resist pattern 41, the n-side electrode 16 composed of the first electrode portion 16a and the second electrode portion 16b divided from the deposited second metal film at a predetermined interval is formed.

  As described above, in the semiconductor laser device according to the third embodiment, since the distance between the electrode portions 16a and 16b of the divided electrodes is relatively large as about 10 μm, the lift-off method that is easy to manufacture is used.

(One Modification of Third Embodiment)
Hereinafter, the planar shape of the n-side electrode 16 according to a modification of the third embodiment will be described with reference to the drawings.

  FIG. 8A shows a planar configuration of a semiconductor laser device according to a modification of the third embodiment. As shown in FIG. 8A, the divided region 16 c located between the first electrode portion 16 a and the second electrode portion 16 b of the n-side electrode 16 is in the longitudinal direction (stripe direction) of the p-side electrode 15. Thus, it is formed so as to have a predetermined inclination angle θ (where 0 <θ <90 °) with respect to the direction orthogonal to the substrate plane, that is, the AA line direction.

  In the semiconductor laser device according to the third embodiment, since the n-side electrode 16 is provided on the side of the waveguide (resonator), both electrode portions of the n-side electrode 16 are provided as shown in FIG. When the divided region 16c between 16a and 16b is provided so as to be orthogonal to the direction in which the p-side electrode 15 extends, the first electrode portion 16a and the second electrode portion of the n-side electrode 16 during high output operation. When a drive current is applied to both electrode portions 16b, there is a possibility that a region where the drive current is not injected into the active layer 13 (n-type contact layer) may occur.

  Therefore, in this modification, the divided region 16c between the first and second electrode portions 16a and 16b of the n-side electrode 16 is defined with respect to the longitudinal direction of the p-side electrode 15 and the direction perpendicular to the substrate surface. The inclination angle θ is larger than 0 ° and smaller than 90 °. As a result, in the divided region 16c, the first electrode portion 16a and the second electrode portion 16b appear at least once along the AA line direction, so that a region where no drive current is injected into the active layer 13 does not occur. .

  In addition, as shown in FIG.8 (b), the shape of the division | segmentation area | region 16c may be a zigzag shape which has inclination-angle (theta) 1-theta4, for example. Therefore, including the case of FIG. 8A, when the shape of the divided region 16c is provided in a polygonal line, if one of the plurality of inclination angles θ is larger than 0 ° and smaller than 90 °. good. Furthermore, the shape of the divided region 16c may be curved, and is not limited to FIGS. 8 (a) and 8 (b).

  In general, a laser element using a gallium nitride-based compound semiconductor has a hexagonal crystal structure, so that when uniaxial strain is introduced into the waveguide, the gain is increased and the oscillation characteristics are improved.

  Therefore, by providing an electrode on the side of the waveguide as in the third embodiment, uniaxial strain can be effectively introduced, so that the optical characteristics of the laser element can be improved.

  Further, when the laser structure is formed using the insulating substrate 31 as in the third embodiment, the thickness of the n-type semiconductor portion 12 is about 2 μm. As a result, it is possible to suppress the diffusion of the injection current in the n-type semiconductor unit 12 as compared with the case where the conductive substrate is used. Therefore, by dividing the n-side electrode 16, the active layer 13 can be injected non-uniformly in a direction perpendicular to the substrate surface.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

  FIGS. 9A, 9B and 10 schematically show a semiconductor laser device and a driving method thereof according to the fourth embodiment of the present invention. 9 (a), 9 (b) and 10, the same components as those shown in FIG. 6 (a) are denoted by the same reference numerals.

  In the third embodiment described above, the first electrode portion 16 a and the second electrode portion 16 b of the n-side electrode 16 are formed in one side region of the p-side electrode 15.

  In the fourth embodiment, regions on both sides of the p-side electrode 15 in the n-side semiconductor portion 12 are exposed, and the first electrode portion 16a is formed on almost the entire surface in one exposed region, and the other exposed. In the region, a second electrode portion 16b is formed on a part of the region, for example, on the reflection end face 13b side. That is, the first electrode portion 16 a and the second electrode portion 16 b are formed so that their planar shapes are asymmetric with respect to the p-side electrode 15.

  This configuration is possible because an insulating substrate made of sapphire or the like is used as the substrate, and both the p-side electrode 15 and the n-side electrode 16 are formed on the same surface of the substrate.

  Further, as in the third embodiment, the division for forming the n-side electrode 16 including the first electrode portion 16a and the second electrode portion 16b from the conductive film formed on one exposed region. It is not necessary to perform patterning for determining the width dimension and shape of the region 16c.

  Hereinafter, the operation of the semiconductor laser device configured as described above will be described with reference to the drawings.

(First driving method)
First, a first driving method of the semiconductor laser element according to the fourth embodiment of the present invention will be described. As shown in FIG. 9A, a pulsed drive current is applied to the p-side electrode 15 and the first electrode portion 16a of the n-side electrode 16 during a high output operation. As a result, the drive current is uniformly injected into the active layer.

  On the other hand, as shown in FIG. 9B, at the time of low output operation, a pulsed drive current in which a high frequency signal is superimposed is applied to the p-side electrode 15 and the second electrode portion 16b of the n-side electrode 16 as a signal source. 20 is applied. As a result, drive current is injected non-uniformly into the active layer.

(Second driving method)
Next, a second driving method of the semiconductor laser element according to the fourth embodiment of the present invention will be described.

  As shown in FIG. 10, a first variable resistor 21 is connected between the signal source 20 and the first electrode portion 16 a of the n-side electrode 16, and the second electrode of the signal source 20 and the n-side electrode 16 is connected. The second variable resistor 22 is connected between the unit 16b.

  At the time of high output operation, the resistance value of the first variable resistor 21 is set to approximately 0, the resistance value of the second variable resistor 22 is set to such an extent that current does not flow through the second electrode portion 16b, A pulsed drive current superimposed with a high frequency signal is supplied from the signal source 20. As a result, a drive current is uniformly injected into the active layer 13 during a high output operation.

  On the other hand, at the time of low output operation, the resistance value of the first variable resistor 21 is set so that no current flows through the first electrode portion 16a, and the resistance value of the second variable resistor 22 is set to almost zero. Thus, a pulsed drive current superimposed with a high-frequency signal is supplied from the signal source 20. As a result, the drive current is non-uniformly injected into the active layer 13 during the low output operation.

  In this way, the amount of drive current applied to the first electrode portion 16a is adjusted by the first variable resistor 21, and the amount of drive current applied to the second electrode portion 16b is adjusted by the second variable resistor 22. By this, the amount of emitted light absorbed in the active layer 13 can be adjusted. Thereby, the relative intensity noise at the time of low output operation can be reduced.

  In the first driving method, the high output operation sets the resistance value of the second variable resistor 22 to infinity, and the low output operation sets the resistance value of the first variable resistor 21 to infinity. Equivalent to. Here, instead of the first and second variable resistors 21 and 22, a switch element may be provided for each.

  Further, although the variable resistor is used as means for reducing the drive current amount, an element or a circuit configuration having a function equivalent to that of the variable resistor may be used. Further, the amount of light emission absorbed in the active layer can be adjusted by applying a bias current to the DC signal instead of using the pulsed AC signal as the drive current.

  Further, the self-oscillation operation may be performed using the fourth driving method shown in the first embodiment.

(One Modification of Fourth Embodiment)
Hereinafter, a modification of the fourth embodiment of the present invention will be described with reference to the drawings.

  FIG. 11 schematically shows a semiconductor laser device and a driving method thereof according to a modification of the fourth embodiment of the present invention. In FIG. 11, the same components as those shown in FIG. 10 are denoted by the same reference numerals.

  In this modification, the first electrode portion 16a of the n-side electrode 16 is not provided in a portion facing the second electrode portion 16b with the p-side electrode 15 interposed therebetween.

  This eliminates the need to provide the second variable resistor 22 between the second electrode portion 16b and the signal source 20.

  In the driving method of the semiconductor laser device according to this modification, the resistance value of the variable resistor 21 is set to almost zero during high output operation, and the resistance value of the variable resistor 21 is set to a finite value during low output operation. A pulsed drive current superimposed with a signal is applied to the first electrode portion 16 a and the second electrode 16 b of the p-side electrode 15 and the n-side electrode 16.

  Also in this modification, the first electrode portion 16a and the second electrode portion 16b of the n-side electrode 16 are formed so that their planar shapes are asymmetric with respect to the p-side electrode 15.

  In addition, the first electrode portion 16a and the second electrode portion 16b are formed so as to have an overlapping portion 16d in which adjacent end portions overlap each other in a direction perpendicular to the p-side electrode 15 in the plane. . Thus, even when a driving current is applied to the first electrode portion 16a and the second electrode portion 16b at the time of a high output operation, a region where no driving current is injected into the active layer is prevented. be able to. Thereby, the uniformity of the laser beam at the time of high output operation can be ensured.

(Fifth embodiment)
Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.

  FIG. 12 shows a semiconductor laser device according to the fifth embodiment of the present invention. 12, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

  In the fifth embodiment, a conductive semiconductor substrate 11 such as gallium nitride (GaN) is used as the substrate. Since the semiconductor substrate 11 has conductivity, the first electrode portion 16 a of the n-side electrode 16 that injects a uniform current into the active layer 13 is formed on almost the entire back surface of the semiconductor substrate 11. Thus, in the fifth embodiment, the divided electrodes are divided into the second electrode portion 16b provided on the main surface side of the semiconductor substrate 11 and the first electrode portion 16a provided on the back surface of the semiconductor substrate 11. It is divided.

  As a result, the number of electrodes formed on the main surface side of the semiconductor substrate 11 is one each for the p-side electrode 15 and the second electrode portion 16b of the n-side electrode 16, so that the conventional semiconductor laser element shown in FIG. The configuration is almost the same. As a result, the semiconductor laser element can be mounted by a so-called p-side down (junction down) method in which the p-side electrode 15 is mounted on the upper surface of the submount using a conventional submount. Therefore, after mounting the semiconductor laser device according to the fifth embodiment on the submount by the p-side down method, wiring is also applied to the first electrode portion 16a of the n-side electrode 16 on the back surface of the semiconductor substrate 11. An electrode split type structure in which the n-side electrode 16 is split can be realized.

(Production method)
Hereinafter, a method for manufacturing the semiconductor laser device configured as described above will be described with reference to the drawings.

  FIG. 13A to FIG. 13D show the order of steps in the method of manufacturing a semiconductor laser device according to the fifth embodiment of the present invention.

  First, as shown in the plan view and the left side view of FIG. 13A, as in the third embodiment, an n-type contact layer is formed in a region on one side of the waveguide formation region in the n-type semiconductor unit 12. While being exposed, the p-side electrode 15 is patterned on the p-type semiconductor portion 12 in a stripe shape.

  Next, as shown in the plan view of FIG. 13B, a resist pattern 42 for forming an n-side electrode having an opening 42a on the reflective end face 13b side on the exposed region of the n-type semiconductor portion 12 by photolithography. Form.

  Next, as shown in the plan view of FIG. 13C, a metal film made of a laminate of Ti and Al is deposited on the resist pattern 42 by, for example, vapor deposition, and the resist pattern 42 is lifted off. Thus, the second electrode portion 16b of the n-side electrode 16 is formed from the deposited metal film.

  Next, as shown in the plan view of FIG. 13D, the back surface of the semiconductor light emitting device 11 is polished until the thickness becomes about 100 μm, and then Ti and Al are formed on the entire back surface by vapor deposition or the like. The first electrode portion 16a of the n-side electrode 16 is formed.

  In the first to fifth embodiments, the operation has been described for the case where the semiconductor laser element is used for the pickup unit of the optical disc apparatus, but the present invention is not limited to this. In other words, the semiconductor laser device may be used for applications that require a high output operation with a high output intensity of emitted light and a low output operation with a low output intensity.

1 is a perspective view showing a semiconductor laser device according to a first embodiment of the present invention. (A) And (b) shows the 1st drive method in the semiconductor laser element concerning the 1st Embodiment of this invention, (a) is a typical perspective view at the time of high output operation | movement, (b) FIG. 3 is a schematic perspective view during a low output operation. It is a typical perspective view which shows the 2nd drive method in the semiconductor laser element concerning the 1st Embodiment of this invention. It is a typical perspective view which shows the 3rd drive method in the semiconductor laser element concerning the 1st Embodiment of this invention. (A)-(c) shows the structure of the order of the process of the manufacturing method of the semiconductor laser element concerning the 2nd Embodiment of this invention, (a) and (b) are sectional drawings, (c) is a plane. It is a figure and a left view. (A) And (b) is a typical perspective view which shows the semiconductor laser element concerning the 3rd Embodiment of this invention, and its drive method. (A)-(e) shows the structure of the order of the process of the manufacturing method of the semiconductor laser element concerning the 3rd Embodiment of this invention, (a) is sectional drawing, (b) is a top view, (C) is a plan view and a left side view, and (d) and (e) are plan views. It is a top view which shows the semiconductor laser element which concerns on the modification of the 3rd Embodiment of this invention. (A) And (b) shows the semiconductor laser device concerning the 4th Embodiment of this invention, and its 1st drive method, (a) is a typical top view at the time of high output operation | movement, (b) ) Is a schematic plan view during low output operation. It is a typical top view which shows the semiconductor laser element concerning the 4th Embodiment of this invention, and its 2nd drive method. It is a typical top view which shows the semiconductor laser element concerning the modification of the 4th Embodiment of this invention, and its drive method. It is a perspective view which shows the semiconductor laser element concerning the 5th Embodiment of this invention. (A)-(d) shows the structure of the order of the process of the manufacturing method of the semiconductor laser element concerning the 5th Embodiment of this invention, (a) is a top view and a left view, (b) and ( c) is a plan view, and (d) is a left side view. It is a perspective view which shows the conventional semiconductor laser element.

Explanation of symbols

11 Semiconductor substrate 12 n-type semiconductor part (first semiconductor layer)
13 Active layer (light emitting layer)
13a Emission end face 13b Reflective end face 14 p-type semiconductor part (second semiconductor layer)
15 p side electrode 15a 1st electrode part (divided electrode)
15b Second electrode part (divided electrode)
16 n side electrode 16a 1st electrode part (divided electrode)
16b 2nd electrode part (divided electrode)
16c division area 16d overlap part 20 signal source 21 (first) variable resistor (resistance variable means)
22 Second variable resistor (resistance variable means)
31 Substrate 40 Resist Pattern 40a Opening 41 Resist Pattern 41a First Opening 42 Resist Pattern 42a Opening

Claims (3)

A first semiconductor layer of a first conductivity type composed of a plurality of gallium nitride compound semiconductor layers formed on a substrate with a substantially uniform film thickness;
A second conductivity type second semiconductor layer comprising a plurality of gallium nitride-based compound semiconductor layers formed on the first semiconductor layer with a substantially uniform film thickness;
An active layer that is formed between the first semiconductor layer and the second semiconductor layer to have a substantially uniform thickness and generates emission light;
A first electrode for supplying a driving current to the first semiconductor layer;
A second electrode for supplying a driving current to the second semiconductor layer,
The first electrode or the second electrode is a divided electrode composed of a plurality of conductive members spaced from each other,
The thickness of each layer in the plurality of gallium nitride-based compound semiconductor layers constituting the first semiconductor layer or the second semiconductor layer to which the driving current is supplied from the divided electrode is such that the divided electrode is formed. uniform der in the region between the region and the divided electrode is,
The divided electrode is an n-side electrode that injects electrons into the active layer,
The second electrode is a p-side electrode having a stripe pattern formed on the second semiconductor layer;
The n-side electrode includes a first electrode portion and a second electrode portion formed on a region exposed to one side of the p-side electrode in the first semiconductor layer,
The divided region located between the first electrode portion and the second electrode portion is larger than 0 ° and smaller than 90 ° with respect to the direction in which the p-side electrode extends and the direction perpendicular to the substrate surface A semiconductor light emitting device provided with an inclination angle . The semiconductor light emitting device according to claim 1, intervals of the plurality of conductive members to each other in front Symbol n-side electrode, characterized in that is about 5μm or more. The active layer, a semiconductor light emitting device according to claim 1 or 2, characterized in that it consists of a compound semiconductor containing nitrogen in its composition.

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