JPH10321942A - Semiconductor light emitting device - Google Patents

Abstract

(57) Abstract: In a semiconductor light emitting device using a group III-V compound containing nitrogen, the light emitting characteristics are improved and the operating voltage can be reduced. SOLUTION: On a substrate 11 made of sapphire having a plane orientation of (0001), n-type GaN having a stepped portion on the top is provided.
Layer 13 is formed. On the upper side of the step portion on the n-type GaN layer 13, a first layer of undoped GaN is formed.
Guide layer 15, a multiple quantum well layer 16 including an active layer 16b, and a second guide layer 17 made of undoped GaN.
If, to suppress the diffusion suppressing layer 18 that is a p-type impurity Mg is diffused into the region of the active layer 16b side, p-type Al _0.1
A p-type cladding layer 19 of Ga _0.9 N;
A p-type contact layer 20 made of Ni and a positive electrode 22 formed by stacking a first metal film 22a made of Ni and a second metal film 22b made of Au on the first metal film 22a are sequentially formed. Have been.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor light emitting device comprising a group III-V compound containing nitrogen (N) in an active layer and a cladding layer.

[0002]

2. Description of the Related Art In recent years, a group III-V compound semiconductor containing nitrogen, which can shorten the wavelength of a laser, has been attracting attention as a key device for the next-generation high-density information processing technology.

A conventional semiconductor light emitting device using a group III-V compound semiconductor containing nitrogen will be described below with reference to the drawings.

FIG. 5 is a sectional view showing the structure of a conventional laser device or light emitting diode device made of a III-V compound semiconductor containing nitrogen. As shown in FIG. 5, on a substrate 101 made of sapphire having a plane orientation of (0001),
GaN buffer layer 102 and buffer layer 10
On n, an n-type GaN layer 103 having a step on the top is sequentially formed.

On the upper side of the step on the n-type GaN layer 103, an n-type Ga _0.95 In _0.05 N layer 104, an n-type cladding layer 105 of n-type Al _0.05 Ga _0.95 N,
A multiple quantum well in which an n-type guide layer 106 made of n-type GaN, a barrier layer 107a made of undoped Ga _0.95 In _0.05 N, and an active layer 107b made of undoped Ga _0.8 In _0.2 N are alternately stacked in quadruple. Layer 107;
a p-type Al _0.2 Ga _0.8 N layer 108, a p-type guide layer 109 made of p-type GaN, a p-type cladding layer 110 of p-type Al _0.05 Ga _{0. 95} N, and a contact layer 111 made of p-type GaN , Ni, and Au are sequentially formed.

On the lower side of the step portion on the n-type GaN layer 103, a negative electrode 11 formed by laminating Ti and Al
3 are formed.

The semiconductor light emitting device shown in FIG. 5 has a cavity length of 700 μm, a stripe width of 2 μm, and has a double hetero structure in which a multiple quantum well is formed by a quadruple active layer 107b. Features. With this double hetero structure, continuous oscillation at room temperature with an oscillation wavelength of 408 nm, a threshold voltage of 8 V, a threshold current of 130 mA, a threshold current density of 9 kA / cm ² , and a lifetime of 1 second is realized. (Shuji Nakamura et al .; Applied
Physics Letters Vol. 69 (1996) pp. 4056-4058).

[0008]

However, the conventional semiconductor light emitting device has a problem that the light emitting efficiency is low and the operating voltage is high.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems, improve the light emission characteristics, and reduce the operating voltage.

[0010]

In order to achieve the above object, the present invention provides a semiconductor layer made of AlN which suppresses diffusion of impurities between an active layer and a cladding layer.

A semiconductor light emitting device according to the present invention is formed on a substrate, and formed on a first cladding layer of a first conductivity type made of a group III-V compound containing nitrogen, and on the first cladding layer. An active layer made of a group III-V compound containing nitrogen, and a second cladding layer of a second conductivity type formed on the active layer and made of a group III-V compound containing nitrogen.
A diffusion suppressing layer formed between the active layer and the second cladding layer, the diffusion suppressing layer including AlN that suppresses diffusion of a second conductivity type impurity of the second cladding layer into a region on the active layer side; ing.

A second semiconductor light emitting device according to the present invention is formed on a substrate, and has a first conductive type first clad layer made of a group III-V compound containing nitrogen, and a first clad layer formed on the first clad layer. An active layer made of a group III-V compound containing nitrogen, and a III-V layer formed on the active layer and containing nitrogen.
A second cladding layer of a second conductivity type made of a group III compound, formed between the active layer and the second cladding layer, comprising a plurality of semiconductor layers including a semiconductor layer made of AlN. The second cladding layer includes a diffusion suppressing layer that suppresses diffusion of impurities of the second conductivity type into a region on the active layer side.

According to the first or second semiconductor light emitting device, the second conductive type impurity is formed between the active layer and the second conductive type second clad layer, and diffuses into the active layer side region. Is provided, the Al constituting the AlN is, for example, the same group III element, and has an atomic radius smaller than that of Ga which is most commonly used. Since the gap between the crystal lattices is smaller than that of GaN, impurity atoms cannot be diffused.

[0014] In the second semiconductor light emitting device, it is preferable that the diffusion suppressing layer is formed of a stacked body in which semiconductor layers made of AlN and semiconductor layers made of GaN are alternately stacked. In this case, since the AlN layer and the GaN layer are hetero-joined to each other, the energy band gap of the AlN layer is larger than that of the GaN layer, so that a quantum well can be formed in the GaN layer.

In the first or second semiconductor light emitting device,
The impurity of the second conductivity type is preferably Mg.

In the first or second semiconductor light emitting device,
The diffusion suppressing layer includes a semiconductor layer made of AlN and Al _x Ga
_1-xy In _y N (where x is 0 ≦ x <1;
y is 0 ≦ y ≦ 1. ) Is preferably formed of a stacked body in which semiconductor layers are alternately stacked.

In the first or second semiconductor light emitting device,
The active layer is Ga _1-x In _x N (where x is 0 <x ≦
It is one. ).

[0018]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of a semiconductor light emitting device according to one embodiment of the present invention. As shown in FIG. 1, a buffer layer 12 made of undoped GaN, having a thickness of 30 nm, and improving the consistency of a crystal lattice, and a buffer layer 12 made of undoped GaN, An n-type GaN layer 13 having a thickness of 3.0 μm and having a stepped portion on the upper side is sequentially formed on the upper surface 12.

On the upper side of the step portion on the n-type GaN layer 13, n-type Al _0.1 Ga _0.9 N and a thickness of 5
An n-type cladding layer 14 as a first cladding layer for containing carriers of 00 nm, a first guide layer 15 made of undoped GaN and having a thickness of 100 nm for enhancing the effect of carrier containment, and undoped Ga _0.95 In
A barrier layer 16a made of _0.05 N and having a thickness of 5 nm and an active layer 16b made of an undoped Ga _0.8 In _0.2 N layer and having a thickness of 2.5 nm are alternately laminated in a quintuple pattern, and a further barrier is further formed thereon. The multiple quantum well layer 16 in which the layers 16a are stacked, and undoped GaN having a thickness of 10
A second guide layer 17 for enhancing the effect of confining carriers of 0 nm, a semiconductor layer 181 made of undoped AlN and a semiconductor layer 182 made of undoped GaN are alternately stacked in an eleven-fold manner, and another layer of AlN is further formed thereon. Tier 1
A diffusion suppressing layer 18, which is formed of a laminated body of the semiconductor layers 81 and suppresses diffusion of a p-type impurity into a region on the active layer 16 b side;
A p-type cladding layer 19 as a second cladding layer for confining carriers having a thickness of 500 nm, made of p-type Al _0.1 Ga _0.9 N, and a p-type GaN having a thickness of 3
A first metal film 22a made of Ni surrounded by a p-type contact layer 20 having a thickness of 00 nm and a current narrowing layer 21 having a T-shaped cross section and a leg portion made of silicon oxide; A positive electrode 22 formed by laminating a second metal film 22b made of Au is sequentially formed.

Since sapphire, which is an insulator, is used for the substrate 11 and no negative electrode is provided on the back surface of the substrate, T
Negative electrode 2 formed by laminating i-layer 24a and Al layer 24b
4 are formed.

As shown in the enlarged view of the diffusion suppressing layer 18 in FIG. 1, the diffusion suppressing layer 18 is composed of an AlN (1) layer 18 composed of one atomic layer of AlN in order from the second guide layer 17 side.
1a, GaN (10) layer 1 composed of 10 atomic layers of GaN
82a, AlN (2) layer 181b, GaN
(6) Layer 182b, AlN (3) layer 181c, GaN
(4) Layer 182c, AlN (4) layer 181d, GaN
(3) Layer 182d, AlN (6) layer 181e, GaN
(2) Layer 182e, AlN (10) layer 181f, GaN
(1) Layer 182f, AlN (10) layer 181g, GaN
(2) Layer 182g, AlN (6) layer 181h, GaN
(3) Layer 182h, AlN (4) layer 181i, GaN
(4) Layer 182i, AlN (3) layer 181j, GaN
(6) Layer 182j, AlN (2) layer 181k, GaN
(10) The layer 182k and the AlN (1) layer 1811 are formed.

Hereinafter, a method of manufacturing the semiconductor light emitting device having the above structure will be described.

First, the main surface of the substrate 11 made of sapphire having a plane orientation of (0001) is subjected to a pretreatment such as cleaning using an organic solvent, and then a metalorganic vapor phase epitaxial growth method is used. The substrate 11 is heated in a hydrogen atmosphere of × 133.3 Pa until the temperature reaches 1090 ° C. to remove adsorbed gas, oxides, water molecules, and the like attached to the surface of the substrate 11. Incidentally, the pressure unit Pa is Torr.
And 133.3 Pa ≒ 1 Torr.

Thereafter, the temperature of the substrate 11 is lowered to 550 ° C., and trimethylgallium is supplied onto the substrate 11 at a flow rate of 5.5.
A buffer layer 12 made of undoped GaN is grown on the substrate 11 to a thickness of 30 nm on the substrate 11 by introducing ammonia at a flow rate of 2.5 l / min at a flow rate of sccm. Thereafter, the temperature of the substrate 11 was raised to 1060 ° C., and trimethylgallium was supplied at a flow rate of 0.27 sccm.
By introducing ammonia at a flow rate of 5.0 l / min and silane at a flow rate of 12.5 sccm, an n-type GaN having a thickness of 3.0 μm is formed on the buffer layer 12 on the substrate 11.
The layer 13 is grown.

Next, on the substrate 11, trimethylgallium was flowed at a flow rate of 2.7 sccm, trimethylaluminum was flowed at a flow rate of 5.4 sccm, and ammonia was flowed at a flow rate of 2.5 l / mi.
n and silane at a flow rate of 12.5 sccm,
On the n-type GaN layer 13 on the substrate 11, n-type Al _0.1 Ga
N-type cladding layer 1 made of _0.9 N and having a thickness of 500 nm
Grow 4.

Next, on the substrate 11, trimethyl gallium was flowed at a flow rate of 2.7 sccm, and ammonia was flowed at a flow rate of 2.5 l / cm 2.
min, the n-type cladding layer 14 on the substrate 11
A first guide layer 15 made of undoped GaN and having a thickness of 100 nm is grown thereon.

Next, the temperature of the substrate 11 is lowered to 730 ° C., and trimethylgallium is supplied on the substrate 11 at a flow rate of 2.7 s.
ccm at a flow rate of 27 sccm with trimethylindium
Then, ammonia was introduced at a flow rate of 10 l / min and nitrogen was introduced at a flow rate of 10 l / min, and undoped Ga _0.95 In _0.05 N was formed on the first guide layer 15 on the substrate 11 to have a thickness of 5.0 nm. Is grown.
Subsequently, while maintaining the temperature of the substrate 11, trimethylgallium was flowed on the substrate 11 at a flow rate of 10.8 sccm, trimethylindium was flowed at a flow rate of 27 sccm, ammonia was flowed at a flow rate of 10 l / min, and nitrogen was flowed at a flow rate of 10 l / mi.
n and undoped Ga _0.8 on the barrier layer 16a.
Active layer 16b of In _0.2 N having a thickness of 2.5 nm
Grow. These barrier layer 16a and active layer 16
After repeating the film formation of a total of five pairs of b, a further quantum barrier layer 16a is formed by alternately stacking five layers by stacking another barrier layer 16a thereon.

Next, the temperature of the substrate 11 is raised to 1060 ° C., and trimethylgallium is supplied onto the substrate 11 at a flow rate of 2.7.
A second guide layer 17 made of undoped GaN and having a thickness of 100 nm is grown on the multiple quantum well layer 16 on the substrate 11 by introducing ammonia at a flow rate of 2.5 l / min at sccm.

Next, while maintaining the temperature of the substrate 11 at 1060 ° C., trimethyl aluminum is supplied onto the substrate 11 at a flow rate of 5.
4 sccm and ammonia at a flow rate of 2.5 l / min
And A is placed on the second guide layer 17 on the substrate 11.
The 1N (1) layer 181a is grown. Next, trimethylgallium was introduced into the substrate 11 at a flow rate of 2.7 sccm, and ammonia was introduced at a flow rate of 2.5 l / min.
A GaN (10) layer 182a is grown on the AlN (1) layer 181a on the first. As described above, the AlN layers 181b to 181k and the GaN layers 182b to 182k are alternately grown, and the AlN layers 181b to 182k are grown on the GaN (10) layer 182k.
The diffusion suppression layer 18 is formed by growing the N (1) layer 181l.

Then, on the substrate 11, trimethyl gallium was flowed at a flow rate of 2.7 sccm, trimethyl aluminum was flowed at a flow rate of 5.4 sccm, and ammonia was flowed at a flow rate of 2.5 l / m 2.
In, and cyclopentadienyl magnesium was introduced at a flow rate of 5.0 sccm, and p-type Al _0.1 Ga _0.9 N was formed on the diffusion suppressing layer 18 on the substrate 11 to have a thickness of 50.
A 0 nm p-type cladding layer 19 is grown.

Next, the temperature of the substrate 11 is lowered to 680 ° C., and trimethylgallium is supplied on the substrate 11 at a flow rate of 2.7 s.
At ccm, ammonia was introduced at a flow rate of 5.0 l / min, cyclopentadienyl magnesium was introduced at a flow rate of 5.0 sccm, and the p-type GaN was formed on the p-type cladding layer 19 on the substrate 11 to a thickness of 300 nm. p-type contact layer 2
Grow 0.

Next, the formed substrate 11 is annealed in a nitrogen atmosphere at a temperature of 700 ° C. for 1 hour to form a p-type cladding layer 18, a p-type GaN layer 19 and a p-type contact layer 20. Mg as a p-type impurity ion
Activate.

Next, the positive electrode 22 is placed on the substrate 11 after annealing.
And a method of forming the negative electrode 24 will be described.

First, after forming a mask pattern having an opening in the region where the positive electrode 22 is formed on the p-type contact layer 20 in the substrate 11, a 1 μm-thick mask Ni is deposited over the entire surface of the substrate. . Next, after removing the mask pattern, in an ECR plasma composed of chlorine and hydrogen having a mixing ratio of 1: 1 and a pressure of 133.3 mPa,
RF power 400W, RF frequency 13.56MH
z, and the voltage between the substrate holder holding the substrate 11 and the grid was set to 500 V, respectively, and Ni for mask was set.
Is used as a mask to dry-etch the substrate 11 for 20 minutes to expose the n-type GaN layer 13. Thereafter, under a nitrogen atmosphere at atmospheric pressure, Ni for mask is removed using nitric acid. Note that a metal such as aluminum or a dielectric such as SiO ₂ may be used instead of Ni for the mask.

Next, the entire surface of the substrate 11 is made of SiO _{2 and} has a thickness of 100 nm by the CVD method.
Is deposited. In addition, as the CVD method, light CV
The method D or the plasma CVD method may be used.

Subsequently, after a resist film is applied over the entire surface of the dielectric film on the substrate 11, the positive electrode forming region on the upper surface of the p-type contact layer 20 on the substrate 11 and the substrate are formed by photolithography. N-type Ga on 11
A resist pattern having an opening having a width of 10 μm is selectively formed in each of the negative electrode forming regions on the exposed surface of the N layer 13, and the resist pattern is used as a mask to form a mixture of hydrogen fluoride and fluoride having a mixing ratio of 1:10. Wet etching is performed on the substrate 11 using an aqueous solution containing ammonium to form openings in the positive electrode forming region on the upper surface of the p-type contact layer 20 and the negative electrode forming region on the exposed surface of the n-type GaN layer 13. The current narrowing layer 21 made of SiO ₂ is formed. In this case, unlike the semiconductor light emitting device shown in FIG. 1, the current narrowing layer 21 similar to the positive electrode 22 is formed also on the negative electrode 24.

Next, after removing the resist pattern on the substrate 11 using acetone and O ₂ plasma, the current narrowing layer 21 on the upper surface of the p-type contact layer 20 and the opening of the current narrowing layer 21 are made of Ni. First metal film 2
2a and a second layer of Au on the first metal film 22a.
The positive electrode 22 is formed by sequentially depositing the metal films 22b.

Next, a Ti layer 24a is formed on the current narrowing layer on the upper surface of the n-type GaN layer 13 and the opening of the current narrowing layer.
And an Al layer 24b are sequentially deposited to form the negative electrode 24.

Next, the substrate 11 is cleaved so that the cavity length becomes 0.5 mm, thereby completing a semiconductor light emitting device.

Hereinafter, the characteristics of the semiconductor light emitting device according to this embodiment will be described.

First, regarding the optical characteristics, the oscillation wavelength of the laser beam is 410 nm, and the reflectivity of the end face is 22% for both the front and rear sides. The internal loss of the laser beam is 5cm
⁻¹ , the loss in the resonator is 20 cm ⁻¹ .

Next, the electrical characteristics will be described.

The p-type cladding layer 19 and the n-type cladding layer 1
4 has a carrier density of 1 × 10 ¹⁸ / cm ³ , and the p-type contact layer 20 and the n-type GaN layer 13 have a carrier density of 3 × 10 ¹⁸ / cm ³ .

The mobilities of the p-type cladding layer 19 and the p-type contact layer 20 are each 10 cm ² / V · s,
Type cladding layer 14 and n-type GaN layer 13 each have 25
0 cm ² / V · s, p is sufficiently low in resistivity.
The type clad layer 19, the n-type clad layer 14, the p-type contact layer 20, and the n-type GaN layer 13 are realized.

On the positive electrode 22 side, a p-type contact layer 20 and a first metal film 22 in contact with the contact layer 20
Ohmic contact is realized with Ni which is a
Similarly, on the cathode 24 side, the n-type GaN layer 13 and T
Ohmic contact is also realized with the i-layer 24a.

FIG. 2 is a graph showing current-voltage characteristics of the semiconductor light emitting device according to this embodiment. In FIG. 2, 1
A is a curve representing the output power of the semiconductor light emitting device according to the present embodiment, and 1B is a curve representing the forward voltage applied to the semiconductor light emitting device according to the present embodiment. Meanwhile, 1
0A is a curve representing the output power of the conventional semiconductor light emitting device, and 10B is a curve representing the forward voltage applied to the conventional semiconductor light emitting device. In FIG. 2, the threshold voltage of the semiconductor light emitting device according to the present embodiment is 4.8 V as shown by a curve 1A, and its threshold current is shown by a curve 1B.
As shown in FIG. On the other hand, the threshold voltage of the conventional semiconductor light emitting device is 8 V as shown by a curve 10A, and its threshold current is 130 mA as shown by a curve 10B. The threshold current density of the semiconductor light emitting device according to this embodiment is ² kA / cm ^2.
And that of the conventional semiconductor light emitting device is 9 kA / cm ² . This indicates that the current-voltage characteristics of the semiconductor light emitting device according to the present embodiment are clearly improved as compared with the conventional semiconductor light emitting device.

This is because the p-type impurity Mg is contained in the active layer 1.
This is because the diffusion suppressing layer 18 for suppressing diffusion to the 6b side is provided. That is, since the atomic radius of Al constituting the AlN crystal is smaller than the atomic radius of Ga constituting the GaN crystal, the gap in the AlN crystal is smaller than the gap in the GaN crystal. This is because Mg ions cannot diffuse into the crystal.

Hereinafter, the active layer 16 of the impurity Mg will be specifically described.
The manner in which diffusion to the b-side region is suppressed will be described with reference to the drawings.

FIG. 3 shows a secondary ion mass spectrometer (SIMS).
5 is a graph showing the concentration of Mg, which is a p-type impurity, in the semiconductor light emitting device according to the present embodiment and a conventional semiconductor light emitting device analyzed by using FIG. In FIG. 3, a curve 2 indicates the Mg concentration of the semiconductor light emitting device according to the present embodiment, and a curve 11
Indicates the Mg concentration of the conventional semiconductor light emitting device. The scale A indicating the depth direction indicates the semiconductor light emitting device according to the present embodiment, the scale B indicates the conventional semiconductor light emitting device, and the reference numerals correspond to the respective semiconductor layers or metal layers. As shown by a curve 2 in FIG. 3, the Mg concentration of the semiconductor light emitting device according to the present embodiment is different from that of the p-type cladding layer 1.
Sharply decreased at the interface between 9 and the diffusion suppressing layer 18, 10 ¹⁴ /
cm ³ or less. On the other hand, in the case of the conventional semiconductor light emitting device shown by the curve 11, 10 ¹⁷ / cm ³ or more exists in the active layer 107 region.

As described above, according to the present embodiment, since the diffusion suppressing layer 18 containing AlN is provided between the second guide layer 17 and the p-type cladding layer 19, the p-type cladding layer 1
9 can be suppressed from being diffused into the region on the active layer 16b side. Therefore, since the concentration of the impurity Mg is 10 ¹⁴ / cm ³ or less in the active layer region 16b, the luminous efficiency does not decrease due to the Mg entering the active layer region 16b. As described above, this means that the threshold current density is 2.0 kA /
cm ² , which is one of the factors that can reduce the operating voltage of the light emitting device.

Further, as a feature of the present embodiment, the diffusion suppressing layer 18 is formed of AlN layers 181a-1
FIG. 4A shows a heterojunction in which 811 and GaN layers 182a to 182k are alternately combined.
As shown in the valence band energy band diagram of the diffusion suppressing layer 18 in FIG.
A quantum tunnel level is formed within 182k. Further, the diffusion suppressing layer 18 employs the number of atomic layers and the amount of change in the number of atomic layers so that the quantum tunnel levels of the quantum wells are all equal, that is, the diffusion suppressing layer of FIG. 18, the AlN layers 181a to 181a-1
81l takes the maximum value 10 at the center of the diffusion suppressing layer 18 and takes the minimum value 1 at both ends, while the GaN layer 182a
182k are formed so as to have a maximum value of 10 at both ends of the diffusion suppressing layer 18 and a minimum value of 1 at the central portion, so that a tunnel current flows through each of the GaN layers 182a to 182k. The internal resistance of the device is reduced. Therefore, this also reduces the operating voltage of the light emitting element.

The defect density in the device according to the present embodiment is 10 ⁷ / cm ^2, which is 1/100 or less of the prior art.
The defect density is greatly reduced. This is because, as a result of combining the diffusion suppressing layer 18 containing AlN and the multiple quantum well layer 16 made of Ga _1-x In _x N, the lattice mismatch ratio with respect to GaN is about 10 ^-4 , This is because the matching ratio is reduced to about 1/100.

That is, as shown in FIG. 6, AlN having a lattice mismatch ratio of 3.1% with respect to GaN is formed in the diffusion suppressing layer 18.
, The lattice mismatch rate with respect to GaN is 2.
Compressive strain applied to the active layer 16b of 5% Ga _0.8 In _0.2 N can be canceled. As a result, the lattice mismatch ratio with respect to the p-type cladding layer 19 can be made smaller than that of the conventional active layer, so that defects generated from the active layer 16b are reduced and the crystallinity of the active layer is improved. The characteristics can be improved.

In place of the substrate 11 made of sapphire, a substrate made of SiC, Al ₂ O ₃ , ZnO, Mg
A substrate made of an oxide such as Al ₂ O ₄ or LiAlO ₂ may be used, and a similar effect can be obtained by using an inclined SiC substrate.

The AlN layer 181 in the diffusion suppressing layer 18
Instead of AlN layer and Al _x Ga _1-xy In _y N (where x is 0 ≦ x <1 and y is 0 ≦ y ≦ 1)
The same effect can be obtained even with a laminate having a multilayer structure in which layers are alternately repeated.

Further, the same effect can be obtained even when Mg is added to the diffusion suppressing layer 18.

[0058]

According to the first or second semiconductor light emitting device of the present invention, the second conductive type impurity is formed between the active layer and the second conductive type second cladding layer. Is provided with a diffusion suppressing layer containing AlN that suppresses diffusion to the region on the side, so that Al constituting AlN has a smaller atomic radius than, for example, Ga, which is the same group III element, and therefore is made of AlN. Since the gap between the crystal lattices is small, impurity atoms cannot be diffused. Accordingly, impurities of the second conductivity type penetrating into the active layer are suppressed, so that the emission efficiency does not decrease due to the impurities, so that the threshold current density is reduced and the operating voltage can be reduced. .

In the second semiconductor light emitting device, when the diffusion suppressing layer is formed of a stacked body in which the semiconductor layer made of AlN and the semiconductor layer made of GaN are alternately stacked, quantum diffusion is performed on each semiconductor layer made of GaN by a heterojunction. Since the well is formed, if the heterojunction is formed such that the quantum tunnel levels generated between a plurality of adjacent quantum wells are all equal, a tunnel current flows through the diffusion suppression layer. Even if provided, the internal resistance of the light emitting element will be reduced. Therefore, the operating voltage of the light emitting element is reduced.

In the first or second semiconductor light emitting device,
When the impurity of the second conductivity type is Mg, the second conductivity type can be easily and surely turned to the p-type.

In the first or second semiconductor light emitting device, the diffusion suppressing layer is formed of a semiconductor layer made of AlN and Al _x.
When a semiconductor layer composed of Ga _1-xy In _y N (where x is 0 ≦ x <1 and y is 0 ≦ y ≦ 1) is formed, the semiconductor layer is made of a laminate in which the semiconductor layers are alternately laminated. III-V containing nitrogen
When an active layer made of Ga _1-x In _x N is used as the group III compound, the lattice matching is improved and the light emission characteristics are improved.

In the first or second semiconductor light emitting device, when Ga _1-x In _x N (where x is 0 <x ≦ 1) is used for the active layer, a short wavelength is obtained. The semiconductor light emitting device that generates the laser light can be reliably realized.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view showing a semiconductor light emitting device according to one embodiment of the present invention.

FIG. 2 is a graph showing current-voltage characteristics of a semiconductor light emitting device according to one embodiment of the present invention.

FIG. 3 is a graph showing the Mg concentration as a p-type impurity in the semiconductor light emitting device according to one embodiment of the present invention and a conventional semiconductor light emitting device.

4A and 4B show a diffusion suppressing layer in a semiconductor light emitting device according to an embodiment of the present invention, wherein FIG. 4A is a diagram showing a valence band energy band and a quantum tunnel level, and FIG. FIG. 4 is a cross-sectional view of a diffusion suppression layer corresponding to FIG.

FIG. 5 is a sectional view showing a configuration of a conventional semiconductor light emitting device.

FIG. 6 is a graph showing a relationship between a band gap and a lattice constant of a typical III-V compound semiconductor.

[Explanation of symbols]

 Reference Signs List 11 substrate 12 buffer layer 13 n-type GaN layer 14 n-type clad layer (first clad layer) 15 first guide layer 16 multiple quantum well layer 16a barrier layer 16b active layer 17 second guide layer 18 diffusion suppression layer 181 AlN semiconductor layer 181a AlN (1) layer 181b AlN (2) layer 181c AlN (3) layer 181d AlN (4) layer 181e AlN (6) layer 181f AlN (10) layer 181g AlN (10) layer 181h AlN ( 6) Layer 181i AlN (4) layer 181j AlN (3) layer 181k AlN (2) layer 181l AlN (1) layer 182 GaN Semiconductor layer 182a GaN (10) layer 182b GaN (6) layer 182c GaN (4) Layer 182d GaN (3) layer 182e GaN (2) layer 182f GaN (1) 182g GaN (2) layer 182h GaN (3) layer 182i GaN (4) layer 182j GaN (6) layer 182k GaN (10) layer 19 p-type cladding layer (second cladding layer) 20 contact layer 21 current narrowing layer 22 Positive electrode 22a First metal film 22b Second metal film 24 Negative electrode 24a Ti layer 24b Al layer

 ──────────────────────────────────────────────────の Continuing on the front page (72) Yoshihiro Hara 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Isao Kidoguchi 1006 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. ( 72) Inventor Masahiro Kume 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Yuzaburo 1006 Odaka Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] A III-V formed on a substrate and containing nitrogen
A first cladding layer of a first conductivity type made of a group III compound; and a III- layer formed on the first cladding layer and containing nitrogen.
A semiconductor light emitting device comprising: an active layer made of a group V compound; and a second cladding layer of a second conductivity type formed on the active layer and made of a group III-V compound containing nitrogen. A diffusion suppressing layer formed between the first cladding layer and the second cladding layer, the diffusion suppressing layer including AlN that suppresses diffusion of a second conductivity type impurity of the second cladding layer into a region on the active layer side. A semiconductor light emitting device, comprising: 2. A III-V film formed on a substrate and containing nitrogen.
A first cladding layer of a first conductivity type made of a group III compound; and a III- layer formed on the first cladding layer and containing nitrogen.
A semiconductor light emitting device comprising: an active layer made of a group V compound; and a second cladding layer of a second conductivity type formed on the active layer and made of a group III-V compound containing nitrogen. And a plurality of semiconductor layers including a semiconductor layer made of AlN, wherein a second conductivity type impurity of the second cladding layer is formed in a region on the active layer side. 1. A semiconductor light emitting device comprising a diffusion suppressing layer for suppressing diffusion into a semiconductor light emitting device. 3. The semiconductor light emitting device according to claim 2, wherein the diffusion suppressing layer is formed of a stacked body in which semiconductor layers made of AlN and semiconductor layers made of GaN are alternately stacked. 4. The semiconductor light emitting device according to claim 1, wherein the impurity of the second conductivity type is Mg. 5. The semiconductor device according to claim 1, wherein the diffusion suppressing layer includes a semiconductor layer made of AlN and Al _x Ga _{1 -xy} In _y N
(Where x is a real number satisfying 0 ≦ x <1 and y is 0 ≦
It is a real number of y ≦ 1. 3. The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting device comprises a stacked body in which semiconductor layers are alternately stacked. 6. The active layer is formed of Ga _1-x In _x N (provided that
X in the expression is a real number satisfying 0 <x ≦ 1. The semiconductor light-emitting device according to claim 1, wherein