JP3900128B2 - ZnSe light emitting device - Google Patents

Description

  The present invention relates to a ZnSe-based light emitting device using a ZnSe-based compound semiconductor belonging to a II-VI group compound semiconductor.

  A ZnSe crystal is a direct transition semiconductor having a band gap of 2.7 eV at room temperature, and is expected as a light-emitting element material in a blue-green region. In particular, since it was shown in 1990 that a p-type ZnSe film can be formed by doping plasma-excited nitrogen, ZnSe-based light emitting devices have come to the spotlight.

  The present inventors have devised a white LED (Light Emitting Diode) having a new configuration using a ZnSe substrate and put it into practical use. These white LEDs are elements utilizing SA (Self-Activated) light emission of an n-type ZnSe substrate. As a specific structure, a light emitting layer composed of a ZnCdSe active layer and a ZnMgSSe clad layer is formed on an n-type ZnSe substrate, and a p-type electrode is formed on the epitaxial film side surface constituting the laminated structure including the light emitting layer. The light emitting device has a laminated structure in which an n electrode is disposed on the back surface of the ZnSe substrate. When electricity is passed between the two electrodes and blue light (wavelength around 485 nm) is emitted from the active layer, part of the blue light is emitted as it is and part of it is incident on the substrate side. The blue light incident on the substrate excites the SA center of the substrate, and as a result, SA light is induced. This SA light emission has a peak around 590 nm, and by mixing it with blue light having a wavelength of 485 nm at an appropriate ratio, light emission that appears white to human eyes can be obtained. An upper white LED is expected to be put to practical use because it has a low driving voltage of about 2.7 V and a relatively high luminous efficiency.

In a semiconductor light emitting device, a light emitting layer (active layer) is sandwiched between an n-type clad layer and a p-type clad layer, and has a band gap smaller than the band gap of both clad layers. Current is injected into the active layer from the clad layers on both sides, and light emission is caused by interband transition of the current carrier. Electrons injected from the n-type cladding layer into the active layer mainly follow the following process.
(A1) Recombines with holes to emit light.
(A2) Leaks (overflows) into the p-type cladding layer and non-radiative recombination occurs in the p-type cladding layer.

  When the ratio (a2) is large, the light emission component is reduced, so that the light output of the light emitting element (LD, LED) becomes small.

It is known that in order to solve the problem of the decrease in light output caused by the above (a2), the energy barrier (hetero barrier ΔEc) against electrons generated between the active layer and the p-type cladding layer may be increased. ing. More specifically, the heterobarrier ΔEc is the difference between the quasi-Fermi level of electrons in the active layer and the energy at the bottom of the conduction band of the p-type cladding layer. Although it is difficult to accurately calculate the hetero barrier ΔEc, there are the following three methods for increasing the hetero barrier.
(B1) Increase the difference ΔEg between the band gap of the active layer and the band gap of the p-type cladding layer.
(B2) The carrier density of the p-type cladding layer is increased and the Fermi level of the p-type cladding layer is lowered.
(B3) Decreasing the current density injected into the active layer.

Of the above three methods, the method (b3) cannot be adopted as long as it aims at realizing a light-emitting element with high luminance. As a method of the above (b1), for example, in a ZnSe light emitting element, it has been proposed to use a ZnMgSSe layer as a cladding layer (for example, Patent Document 1). In the case of using ZnMgSSe, the band gap can be increased to about 4.4 eV under the condition of matching the lattice constant with ZnSe.
JP-A-5-75217

  However, in the case of the ZnSe system, the method (b1) and the method (b2) cannot be handled independently, and the pursuit of only the method (b1) does not solve the problem. The reason why the method (b1) and the method (b2) are related to each other is the doping characteristics of the ZnSe-based compound semiconductor. Next, doping characteristics of the ZnSe-based semiconductor will be described.

  In a II-VI group compound semiconductor to which a ZnSe-based compound semiconductor belongs, if p-type impurities are introduced in an equilibrium state, sufficient p-type conductivity cannot be stably obtained. It is known that this is possible only when nitrogen is introduced under low temperature growth by MBE (Molecular Beam Epitaxy) method. However, this doping becomes more difficult as the band gap becomes larger, and the highest p-type carrier density obtained becomes smaller as the band gap becomes larger. The result of this phenomenon is shown in FIG.

  FIG. 7 is a diagram showing the relationship between the band gap of ZnMgSSe whose composition ratio is adjusted so that the lattice constant matches that of ZnSe, and the effective p-type carrier density (Na−Nd). Here, Na is the acceptor density and Nd is the donor density. It can be seen that (Na−Nd) decreases when the band gap of ZnMgSSe is increased. The cause is considered to be that donor defects (details are not well understood) are easily formed when the band gap is increased even if only nitrogen (N) which is a p-type impurity is doped. . That is, in the ZnSe-based compound semiconductor, when the band gap is increased, the donor defect density increases, that is, Nd increases and the p-type carrier density does not substantially increase. Carrier density decreases.

  From the above phenomenon, it can be seen that there is an optimum value of the band gap of the p-type cladding layer to maximize the hetero barrier ΔEc. That is, there is a correlation as schematically shown in FIG. In FIG. 8, the optimum band gap value is displayed as a critical value. By combining the solutions (b1) and (b2) above, the maximum hetero barrier ΔEc is realized by setting the band gap of the p-type cladding layer to the above critical value, and electron leakage is sufficiently suppressed. Be expected.

  The optimum band gap value depends on the doping technique and cannot be generally stated, but is in the vicinity of 2.9 eV to 3.0 eV. There is no problem if the heterobarrier ΔEc obtained with this optimum band gap becomes sufficiently large, and as a result, the above-described electron leakage becomes sufficiently small. However, contrary to the above expectation, in practice, even when the optimum band gap in the p-type cladding layer is realized, the hetero barrier ΔEc is not large enough, and a non-negligible amount of electrons are transferred from the active layer to the p-type cladding. It turned out to leak into the layer.

  A further serious problem of a ZnSe-based compound semiconductor light emitting device is that the leakage of electrons to the p-type cladding layer not only lowers the light emission efficiency but also shortens the lifetime of the light emitting device. Next, this phenomenon will be described.

  As described above, in the II-VI group compound semiconductor to which the ZnSe system belongs, the stability of the p-type dopant is low. Therefore, not only the p-type carrier density cannot be increased, but also donor defects are formed by the energy released when electrons leaked into the p-type cladding layer recombine with holes in the p-type cladding layer, The p-type carrier density is reduced. When the p-type carrier density is reduced, the hetero barrier ΔEc is reduced, and the barrier against electron leakage becomes difficult. As a result, (electron leakage into the p-type cladding layer) → (decrease in p-type carrier density in the p-type cladding layer) → (decrease in heterobarrier ΔEc) → (acceleration of electrons into the p-type cladding layer) → It falls into the vicious circle of ... and the way the luminous efficiency decreases in a catastrophic manner. That is, after a short period during operation, it enters into a rapid deterioration mode. Because of the above phenomenon, it has been considered that it is difficult to extend the lifetime because the lifetime is short as an intrinsic property of the ZnSe-based light emitting device.

  An object of the present invention is to provide a ZnSe-based light-emitting element capable of extending the lifetime of the light-emitting element in a ZnSe-based light-emitting element.

The ZnSe light emitting device of the present invention is a ZnSe light emitting device that is formed on a compound semiconductor substrate and includes an active layer positioned between an n-type cladding layer and a p-type cladding layer. A barrier layer having a band gap larger than that of the p-type cladding layer is provided between the active layer and the p-type cladding layer. Barrier layer, i-type _{Zn 1-xy Mg x Be y} Se (0.01 ≦ y ≦ 0.1) Ru der.

  With this configuration, electrons injected into the active layer are prevented from moving to the p-type cladding layer by a barrier potential due to a band gap larger than that of the p-type cladding layer of the barrier layer. For this reason, the lifetime of this ZnSe light emitting element can be greatly improved.

  The main point of this configuration is that the two roles of a normal p-type cladding layer are "supplying holes to the active layer" and "suppressing electron leakage by forming a heterobarrier". The role of “leakage suppression” is to be assigned to the barrier layer. The p-type cladding layer plays only the role of “supplying holes to the active layer”. If only "supply of holes to the active layer" is required, the demand for a large band gap and a large carrier density for the p-type cladding layer is not so strong. Regarding the suppression of electron leakage by the barrier layer, if the band gap of the barrier layer is sufficiently large, even if there is no increase in the heterobarrier ΔEc obtained by increasing the carrier density, it is sufficiently large with respect to the quasi-Fermi level of the active layer. Heterogeneous barrier ΔEc can be secured.

  A notable advantage of the above configuration is that the electron confinement efficiency does not depend much on the carrier density of the p-type cladding layer. Therefore, even if the carrier (hole) density of the p-type cladding layer is reduced by the current leaked beyond the barrier layer, the electron confinement efficiency is hardly affected and maintained. As a result, the acceleration due to the vicious circle of the increasing tendency of the leak amount, which has been a problem in the conventional structure, is not induced, and the catastrophic element deterioration is prevented.

  Here, the confinement effect by the barrier layer will be explained. Basically, if the difference between the pseudo-Fermi level of electrons in the active layer and the energy level at the bottom of the conduction band in the barrier layer is large, the confinement efficiency is improved. . In order to increase the energy difference, that is, the hetero barrier ΔEc, basically, the band gap of the barrier layer may be increased. Therefore, when using ZnMgSSe for the barrier layer, the band gap of the barrier layer may be increased by increasing the composition ratio of Mg and S. At this time, the carrier density of the barrier layer is not important, and there is no need to limit the carrier density in the conventional p-type cladding layer.

  Although it is not necessary to intentionally dope the p-type impurity in the cladding layer, there is no problem even if it is somewhat doped. The material constituting the barrier layer is not limited to ZnMgSSe. As long as the band gap is larger than that of the clad layer and the band gap is larger, the energy level at the bottom of the conduction band is increased (it may be said that the electron affinity is decreased), and the material may not be ZnMgSSe. However, it is necessary to approximately match the lattice constant with that of a semiconductor substrate such as a ZnSe substrate. An example of such a material is ZnMgBeSe. Although it is the difference between ZnMgSSe and ZnMgBeSe, it is known that ZnMgBeSe has a smaller electron affinity, and if the band gap is the same, ZnMgBeSe is preferable because the electron confinement efficiency becomes higher.

  When the barrier layer is formed of ZnMsSSe or ZnMgBeSe, the electron confinement efficiency increases as the band gap increases. However, if it is too large, the crystallinity of the film constituting the barrier layer tends to deteriorate, and it should not be too large. Good. Also, if the band gap of the barrier layer is made larger than the band gap of the p-type cladding layer, it becomes a barrier against the injection of holes from the p-type cladding layer into the active layer, thereby causing a problem of lowering the light emission efficiency.

  Here, in the case of a III-V compound semiconductor light emitting device, the formation of a barrier against the injection of holes from the p-type cladding layer into the active layer is not a problem. However, unlike a III-V compound semiconductor, in a ZnSe-based compound semiconductor, if the above-described barrier exists between the barrier layer and the p-type cladding layer, the p-type doping becomes unstable and is likely to deteriorate. Therefore, it is desirable that the barrier against the injection of holes from the p-type cladding layer into the active layer is small. When ZnMgSSe and ZnMgBeSe are compared with respect to the barrier, ZnMgBeSe is preferable because the barrier against holes is smaller or the barrier is not formed when the band gap is the same.

  As can be seen from the above description, there is an optimum value for the band gap of the barrier layer. The optimum value depends on the material of the barrier layer, the band gap of the p-type cladding layer, the stability of the p-type doping of the p-type cladding layer, and cannot be determined unconditionally. However, there is an optimum value for the band gap of the barrier layer in the range of 0.025 eV to 0.5 eV larger than the band gap of the p-type cladding layer. Even if there is a slight deviation from the optimum value, the above-mentioned role of the barrier layer can be expected as long as the band gap is in the range of 0.025 eV to 0.5 eV larger than the band gap of the p-type cladding layer.

  Next, light-emitting elements according to embodiments of the present invention will be introduced with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a ZnSe-based light emitting device in an embodiment of the present invention. An n-type ZnSe-based buffer layer (hereinafter referred to as an n-type buffer layer) 2 is positioned on the n-type compound semiconductor substrate 1, and an n-type ZnMgSSe cladding layer (hereinafter referred to as an n-type cladding layer) 3 is formed thereon. . As the n-type compound semiconductor substrate 1, an n-type ZnSe single crystal substrate or an n-type GaAs single crystal substrate can be used. An n-type GaAs single crystal substrate is easy to form a ZnSe-based epitaxial film and is inexpensive.

  An active layer 4 in which a quantum well layer and its barrier layer are stacked is positioned on the n-type cladding layer 3, and a barrier layer (first cladding layer) 5 is positioned on the active layer 4. A p-type ZnMgSSe cladding layer (hereinafter referred to as a p-type cladding layer or a second cladding layer) 6 is formed.

As shown in FIG. 2, i-type Zn _1-xy Mg _x Be _y Se (0.01 ≦ y ≦ 0.1) can be used for the barrier layer. In addition, as shown in FIG. 3, i-type Zn _1-xy Mg _x S _y Se (0.01 ≦ x ≦ 0.1) may be used for the barrier layer. However, the barrier layer is not limited to the intrinsic compound semiconductor, and may include a p-type impurity.

  A p-type ZnSe buffer layer 7 is located on the p-type cladding layer, a p-type ZnSe / ZnTe superlattice contact layer 8 is formed thereon, and a p-electrode 9 is further provided thereon. The n-type compound semiconductor substrate 1 is provided with an n-electrode, which is not shown. Light is emitted by applying a voltage between the n-electrode and the p-electrode to inject current into the active layer.

  FIGS. 4 and 5 are diagrams showing band structures in the n-type cladding layer 3 / active layer 4 / barrier layer 5 / p-type cladding layer 6. A barrier layer (first cladding layer) 5 is provided between the active layer 4 and the p-type cladding layer (second cladding layer) 6 to form a barrier potential against leakage of electrons from the active layer to the p-type cladding layer. Yes. That is, electrons are confined in the active layer. Here, in FIG. 4, there is no discontinuity between the barrier layer and the valence band of the p-type cladding layer, and the junction is continuous, but such junction is possible only when ZnMgBeSe is used as the barrier layer. When ZnMgSSe is used for the barrier layer, a barrier is also formed on the valence band side at the interface between the barrier layer and the p-type cladding layer as shown in FIG. Even when ZnMgBeSe is used for the barrier layer, if the band gap is too large, a barrier is formed on the valence band side as shown in FIG.

  Next, the manufacturing method of the light emitting element in embodiment of this invention is demonstrated. First, the stacks 2 to 8 shown in FIG. 1 were formed on a conductive ZnSe substrate having a plane orientation (100) by the MBE method. Regarding the composition ratio of the n-type and p-type cladding layers, the band gap was 2.9 eV at room temperature, and the composition was approximately lattice-matched with the ZnSe substrate. As the barrier layer, a ZnMgBeSe layer with a band gap of 3.1 eV (room temperature) and a thickness of 20 nm, which is also approximately lattice matched with the ZnSe substrate, was used. Here, since the Mg composition required for each of the n-type ZnMgSSe layer 3, the barrier layer (first cladding layer) 5, and the p-type ZnMgSSe layer (second cladding layer) is different, Mg required for growth The flux is different. Therefore, a plurality of K cells may be used as the Mg source, but in this embodiment, a method of changing the temperature of the K cell for Mg during growth using a single K cell is employed. Therefore, the temperature of the Mg K cell was changed before the growth of the barrier layer 5 and the p-type ZnMgSSe layer 6, and the growth was stopped until the temperature was stabilized.

  It is a measurement of the band gap of each layer at room temperature, but using the emission wavelength of PL (Photo-Luminescent) emission (emission by exciton recombination) near the band edge at 4.2 K, the following formula (I) The band gap at room temperature was calculated using the conversion formula.

Eg (eV) = {1240 / λ _4.2PL (nm)} − 0.1 (I)
In the above formula (I), 0.1 eV is subtracted, which is a decrease in the band gap accompanying the temperature increase from 4.2 K to room temperature. The above conversion formula is not necessarily accurate and includes a systematic error, but is adopted as an approximate formula because it is simple.

  The matching of the lattice constant can be evaluated by the deviation of the diffraction angle of (400) diffraction by X-rays. When the diffraction lines are measured after forming the laminated structures 2 to 8 by the MBE method, both strong diffraction from the ZnSe substrate and relatively weak diffraction from the cladding layer are observed. The degree of lattice matching of the cladding layer can be evaluated from the difference in diffraction angle between the two. However, since a diffraction peak cannot be observed for the barrier layer, a relatively thick ZnMgBeSe or ZnMgSSe film is formed on a ZnSe substrate in the growth for setting conditions performed in advance, and the X-ray diffraction angle is measured to form a lattice. Assess consistency. The same measurement is performed for the band gap.

  Although Cl is used as the n-type impurity and N is used as the p-type impurity, this selection is not an essential problem in the present invention, and the impurity to be used is not limited to the impurity.

  Although ZnMgSSe is used for the n-type and p-type cladding layers, and the same value is adopted as the band gap of both, these selections are not essential to the present invention. Different ZnSe-based compound semiconductors may be used for the n-type and p-type cladding layers, and the band gaps of the two may be different.

  As a comparative example, an LED having a conventional structure in which the barrier layer (first cladding layer) 5 is removed from the laminated structure of FIG. Here, the thickness and band gap of the other layers of the laminated structure were made to be the same as in this embodiment (example of the present invention).

  After forming each of the layers 2 to 8 in the laminated structure of FIG. 1, an n electrode made of Ti / Au was formed on the back side of the ZnSe substrate 1. A semitransparent Au electrode having a thickness of about 100 mm was formed on the p-type ZnSe / ZnTe superlattice contact layer 8. Thereafter, a scribe break was made on a 400 μm square, and bonding was performed on the stem to produce an LED for life evaluation.

In addition, (400) diffraction by X-rays (Cu Kα ₁ line) is measured before electrode formation, and the deviation of the diffraction peaks of the n-type and p-type cladding layers is 400 seconds or less compared to the diffraction peak of the ZnSe substrate. It was confirmed. As for ZnMgBeSe, in the growth for setting conditions performed immediately before the LED growth, (400) diffraction by X-ray (Cu Kα ₁ line) is measured, and the deviation is still 400 compared with the diffraction peak of the ZnSe substrate. Confirmed that it was less than a second.

  The lifetimes of the LED of the present invention and the LED of the comparative example manufactured according to the above manufacturing procedure were measured. As a measuring method, a change in luminance was measured while flowing a constant current of 15 mA at 70 ° C. FIG. 6 shows the measurement results. According to FIG. 6, it can be seen that in the comparative example having the conventional structure, the luminance decreases to about 70% of the initial luminance in about 20 hours. On the other hand, in the example of the present invention, it can be seen that it takes 400 hours or more to decrease to about 70% of the initial luminance. It can be seen that, in the LED of the present invention, the deterioration of luminance with time is significantly suppressed.

  In addition to the fact that the p-type cladding is less likely to be deteriorated because the electrons are less likely to leak to the p-type clad side, the above-described degradation is maintained even if the p-type cladding layer is deteriorated. It comes from that. Conventional ZnSe-based light-emitting elements have been prevented from being put into practical use because they are easily deteriorated and have a short lifetime. However, the light-emitting elements according to the present invention have the disadvantages eliminated by having the above-described structure. .

  Next, other embodiments of the present invention will be described enumerated including the above-described embodiments of the present invention.

  The band gap of the barrier layer is preferably larger by 0.025 eV to 0.5 eV than the p-type band gap.

  It is difficult to sufficiently suppress the movement of electrons injected into the active layer into the p-type cladding layer only if the band gap of the barrier layer is larger than that of the p-type cladding layer by less than 0.025 eV. If the band gap of the barrier layer is larger than that of the p-type cladding layer by 0.5 eV, the crystal becomes unstable and adversely affects device characteristics.

  In the band gap of the barrier layer, the energy of the valence band may be almost the same as that of the p-type cladding layer, and the energy of the conduction band may be larger than that of the p-type cladding layer.

  According to this configuration, only leakage of electrons in the active layer to the p-type cladding layer is suppressed, and the valence band holes are hardly affected. For this reason, the lifetime can be extended without adversely affecting the device characteristics.

  The barrier layer may be a II-VI group compound semiconductor containing Be. With this configuration, the lifetime of the ZnSe-based light emitting element can be extended without deteriorating the light emission characteristics.

The barrier layer may be Zn _1-xy Mg _x Be _y Se (0.01 ≦ y ≦ 0.1).

With this configuration, the band bottom of the conduction band of the barrier layer is sufficiently higher than that of the p-type cladding layer, and the top of the band of the valence band of the barrier layer can be made not significantly different from the p-type cladding layer. As a result, it is possible to extend the device life without deteriorating the light emission characteristics. Moreover, an epitaxial barrier layer and a p-type cladding layer can be formed, and high luminous efficiency can be ensured. The Zn _1-xy Mg _x Be _y Se (0.01 ≦ y ≦ 0.1) layer is very difficult to introduce a p-type impurity, but if a p-type impurity can be introduced, the p-type cladding layer As long as it has a larger band gap, it may contain a p-type impurity.

The barrier layer may be Zn _1-x Mg _x S _y Se _1-y (x and y are in the range of 0 to ₁ ).

With this configuration, the band gap of the barrier layer can be made sufficiently larger than that of the p-type barrier layer, and electrons from the active layer can be prevented from flowing into the p-type barrier layer. As a result, the life of the light emitting element can be extended. The Zn _1-x Mg _x S _y Se _1-y (x, y ranges from 0 to ₁ ) layer is preferably an i-type compound semiconductor, but as long as it has a larger band gap than the p-type cladding layer, A p-type impurity may be included.

  The barrier layer may have a thickness of 5 nm or more and not more than the thickness of the active layer. If the thickness of the barrier layer is less than 5 nm, the electrons in the active layer flow into the p-type cladding layer due to the tunnel effect, making it difficult to function as a barrier potential. Further, when the thickness exceeds the thickness of the active layer, the rigidity of the barrier layer becomes high, and the distortion matching is shifted to cause a large distortion. As the upper limit of the thickness of the barrier layer, the thickness of the active layer may be set as the upper limit, or separately, 100 nm may be specifically set as the upper limit of the thickness.

  An n-type ZnSe single crystal substrate may be used as the compound semiconductor substrate. By using this substrate to form an epitaxial film with good crystallinity, a light-emitting element with high emission efficiency and a long lifetime can be manufactured.

  An n-type GaAs single crystal substrate may be used as the compound semiconductor substrate. A GaAs substrate is inexpensive and a ZnSe-based epitaxial film can also be formed. Therefore, an inexpensive and long-life light emitting element with high light emission efficiency can be obtained.

  In the laminated structure including the compound semiconductor substrate constituting the ZnSe-based light emitting device, the X-ray diffraction peak of the plane orientation used as an indicator of strain from the substrate, and the X-ray diffraction peak of the plane orientation from the laminated structure The shift may be 1000 seconds or less.

  According to this configuration, it is possible to obtain a long-life ZnSe-based light-emitting element having excellent light emission characteristics by suppressing the above-described deviation. The plane index used for the index of strain of the compound semiconductor substrate is usually the (400) plane. The suppression of the deviation leads to suppression of distortion generated in the light emitting element.

  While the embodiments of the present invention have been described above, the embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is not limited to these embodiments. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The ZnSe-based light emitting device of the present invention does not suffer from the cumulative crystalline alteration due to the leakage unique to the II-VI group compound semiconductor by disposing the barrier layer which is a leakage preventing means having no leakage sensitivity. For this reason, it is possible to stably suppress the leakage of electrons, and it is possible to perform illumination with a long lifetime and good light emission efficiency at low cost. Therefore, it is expected to be widely applied to various lighting devices.

It is a figure which shows the ZnSe type | system | group light emitting element in embodiment of this invention. It is a figure which shows the laminated structure at the time of using ZnBeMgSe for a barrier layer. It is a figure which shows the laminated structure at the time of using ZnMgSSe for a barrier layer. It is a figure which shows the band structure at the time of using ZnBeMgSe for a barrier layer. It is a figure which shows the band structure at the time of using ZnMgSSe for a barrier layer. It is a figure which shows the lifetime test result of the light emitting element on acceleration conditions. It is a figure which shows the relationship between (Na-Nd) and the band gap Eg in ZnMgSSe. It is a figure which shows the relationship between the magnitude | size of the band gap of a p-type clad layer, and conduction band side band offset (DELTA) Ec.

Explanation of symbols

  1 n-type compound semiconductor substrate, 2 n-type ZnSe buffer layer, 3 n-type ZnMgSSe cladding layer, 4 active layer, 5 barrier layer (first cladding layer), 6 p-type ZnMgSSe cladding layer (second cladding layer), 7 p Type ZnSe buffer layer, 8p type ZnSe / ZnTe superlattice contact layer, 9p electrode.

Claims (8)

A ZnSe-based light emitting device comprising an active layer formed on a compound semiconductor substrate and positioned between an n-type cladding layer and a p-type cladding layer,
A barrier layer having a band gap larger than that of the p-type cladding layer between the active layer and the p-type cladding layer;
The barrier layer, i-type _{Zn 1-xy Mg x Be y} Se (0.01 ≦ y ≦ 0.1) Ru der, ZnSe-based light-emitting device. 2. The ZnSe-based light emitting device according to claim 1, wherein the n-type cladding layer is an n-type ZnMgSSe layer, and the p-type cladding layer is a p-type ZnMgSSe layer. The barrier layer the size of the band gap 0.025eV~0.5eV larger than the band gap of the p-type cladding layer, ZnSe-based light emitting device according to claim 1 or 2. In the band gap of the barrier layer, the valence energy of the electron band is almost the same as that of the p-type cladding layer, the it is greater than the energy of the conduction band is the p-type cladding layer, one of the claims 1-3 A ZnSe light emitting device according to any one of the above. The ZnSe light emitting element according to any one of claims 1 to 4 , wherein the barrier layer has a thickness in a range of 5 nm or more and not more than the thickness of the active layer. It said compound semiconductor substrate using an n-type ZnSe single crystal substrate, ZnSe-based light-emitting device according to any one of claims 1-5. It said compound semiconductor substrate using an n-type GaAs single crystal substrate, ZnSe-based light-emitting device according to any one of claims 1-6. In the laminated structure including the compound semiconductor substrate constituting the ZnSe-based light emitting device, the X-ray diffraction peak of the plane orientation used as an indicator of strain from the substrate and the X-ray diffraction of the plane orientation from the laminated structure The ZnSe light emitting element according to any one of claims 1 to 7, wherein a deviation from a peak is 1000 seconds or less.

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