JPH118440A - Semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor light-emitting device which is superior in luminance efficiency, temperature characteristic, and electrical properties by a method, wherein a clad layer and an active layer which are both formed of first conductivity-type III-V compound semiconductor and a clad layer of second conductivity-type II-VI compound semiconductor are laminated on a substrate. SOLUTION: An n-type III-V compound semiconductor clad layer 12, an undoped III-V compound semiconductor active layer 13, and a p-type II-VI compound semiconductor clad layer 14 are successively laminated on an n-type III-V compound semiconductor substrate 11 through an organic metal vapor growth method. The p-type II-VI compound semiconductor clad layer 14 is grown at temperatures lower than that of the III-V compound semiconductor clad layer 12 and the undoped III-V compound semiconductor active layer 13 and superior in crystallinity. Therefore, a semiconductor light-emitting device of this constitution is capable of effectively performing optical and carrier confinement, so that it is superior in luminance efficiency, temperature characteristic, and electrical properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor light emitting device,
In particular, it relates to a light emitting diode and a laser diode.

[0002]

2. Description of the Related Art In a conventional semiconductor laser, in order to form a double hetero structure for confining light and carriers, the band gap of a group 2-6 compound semiconductor is limited to a group 3-5 compound semiconductor having the same lattice length. Utilizing the fact that it becomes larger,
For example, as disclosed in JP-A-1-184978, a structure in which an active layer is formed of a Group 3-5 compound semiconductor and a cladding layer is formed of a Group 2-6 compound semiconductor has been used.

[0003]

However, 2-6
The group III compound semiconductor and the group III-V compound have very different semiconductor growth temperatures. When the substrate temperature is increased to grow a group III-V compound semiconductor as an active layer on the group II-VI compound semiconductor, Since the cladding layer of the group 2-6 compound semiconductor is decomposed or diffuses into the active layer to change the electrical and emission characteristics of the active layer, a semiconductor laser cannot be manufactured with good reproducibility. There was a problem.

[0004] The present invention has been made in view of these problems, and by performing light confinement and carrier confinement effectively, is excellent in luminous efficiency, temperature characteristics and electric characteristics, and is easy to manufacture. It is an object to provide a semiconductor light emitting device.

[0005]

According to the present invention, there is provided a first-conductivity-type group III-V compound semiconductor substrate on a first-conductivity-type group III-V compound semiconductor substrate. The present invention relates to a semiconductor light emitting device having a laminated structure including an active layer made of a Group 5 compound semiconductor and a 2-6 clad layer made of a second conductivity type Group 2-6 compound semiconductor.

In this case, the above-mentioned laminated structure may be laminated in direct contact in this order, but may be a laminated structure in which a light guide layer is provided above and / or below the active layer.

When an optical guide layer is provided above the active layer, that is, between the active layer and the 2-6 cladding layer, a group 3-5 compound semiconductor having a larger forbidden band width than that of the active layer or 2-6 is used.
It is preferable that the conductive type be an intrinsic type or a second conductive type with a layer thickness smaller than the emission wavelength, for example, 以下 or less of the emission wavelength, using a group III compound semiconductor.

According to the present invention, since a group 2-6 compound semiconductor having a low growth temperature is grown on a group 3-5 compound semiconductor layer, crystal deterioration due to heat does not occur, and a semiconductor light emitting device can be easily manufactured. . In addition, since the group 2-6 compound semiconductor has a large band gap and a low refractive index, both light and carriers can be strongly confined in the active layer. For this reason, the luminous efficiency of the element increases, and stable luminescence can be obtained even when the temperature rises.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 is a perspective view of a semiconductor laser showing a first embodiment of the present invention, and FIG. 2 is a band structure diagram. To manufacture this semiconductor laser, an n-type 3-5
On a group III compound semiconductor substrate 11, a 3-5 cladding layer 12 made of an n-type group 3-5 compound semiconductor, an active layer 13 made of an undoped group 3-5 compound semiconductor, and a layer 2 made of a p-type group 2-6 compound semiconductor After the 6 cladding layers 14 are sequentially formed by a metal organic chemical vapor deposition (MOVPE) method or a molecular beam crystal growth (MBE) method, a metal material is further vacuum deposited to form a p-electrode 15 and an n-electrode 16. I do. Further, the reflection mirror surfaces 17a, 17b are formed by cleavage or etching.
Is formed to obtain the structure shown in FIG.

2-6 The growth temperature of the cladding layer 14 is 3-5.
Lower than the growth temperature of the cladding layer 12 and the active layer 13,
High-quality crystals can be easily obtained, and diffusion of impurities from the 2-6 cladding layer 14 to the active layer 13 does not occur.

When a positive voltage is applied to the p electrode 15 and a negative voltage is applied to the n electrode 16, electrons injected from the 3-5 cladding layer 12 and holes injected from the 2-6 cladding layer 14 are generated in the active layer 13. Recombines and emits light. The light is reflected by the reflection mirror surfaces 17a, 17
The laser oscillation is obtained by being reflected by b.

FIG. 2 shows a typical example of the band structure in the vicinity of the active layer 13. The forbidden band width of the 2-6 cladding layer 14 is larger than that of the 3-5 cladding layer 12, and the discontinuous value of the valence band edge 21 at the interface between the active layer 13 and the 2-6 cladding layer 14 and the conduction band edge 22. Large discontinuity. Further, since the difference between the Fermi levels of the 3-5 cladding layer 12 and the 2-6 cladding layer 14 is large, the diffusion potential of the pn junction also increases. By these two effects, leakage of electrons and holes from the active layer is reduced, and operation at a high temperature becomes possible. In addition, since the refractive index of the 2-6 cladding layer 14 is smaller than that of the 3-5 cladding layer 12, light is more confined in the active layer 13 and the oscillation threshold current decreases.

Further, since the active layer 13 is made of a Group 3-5 compound semiconductor, the device life is long and the reliability is high. When the 3-5 cladding layer 12 and the active layer 13 are lattice-matched to the group III-V compound semiconductor substrate 11, luminous efficiency and reliability are improved.

In this embodiment, the group 3-5 compound semiconductor substrate and the 3-5 cladding layer are n-type and the 2-6 cladding layer is p-type.
However, the group 3-5 compound semiconductor substrate and the 3-5 cladding layer may be p-type and the 2-6 cladding layer may be n-type.
Although the active layer is a single-layer group 3-5 compound semiconductor,
However, the present invention is not limited to this, and a multiple quantum well structure or the like composed of multiple group 3-5 compound semiconductor layers may be used.

In this embodiment, InP, InAs, InSb, InN, Ga
As, GaP, GaSb, GaN, or the like can be used. As the 3-5 cladding layer and the active layer, InG
aAsP mixed crystal system, AlGaAs mixed crystal system, InGaAlP
A mixed crystal system or the like can be used. In addition, ZnSe, ZnTe, ZnS, CdSe, C
dS, CdTe, BeSe, BeTe, MgZnSSe
A mixed crystal system, a MgZnSeTe mixed crystal system, a MgZnCdSe mixed crystal system, a BeZnSeTe mixed crystal system, a BeZnSeSe mixed crystal system, or the like can be used.

[Embodiment 2] FIG. 3 is a perspective view of a light emitting diode showing a second embodiment of the present invention, and FIG. 4 is a band structure diagram. This light emitting diode comprises a 3-5 cladding layer 32 made of a p-type 3-5 group compound semiconductor, an active layer 33 made of an undoped 3-5 group compound semiconductor, n After sequentially forming and forming a 2-6 cladding layer 34 made of a type 2-6 compound semiconductor, a transparent electrode 35 and a p-electrode 36 are further formed to obtain the structure shown in FIG. The growth temperature of the 2-6 cladding layer 34 is
The temperature is lower than the growth temperature of the cladding layer 32 and the active layer 33, and the crystal can be easily grown by MOVPE or MBE.

When a positive voltage is applied to the p-electrode 36 and a negative voltage is applied to the transparent electrode 35, holes injected from the 3-5 cladding layer 32 and electrons injected from the 2-6 cladding layer 34 are generated in the active layer 33. Recombines and emits light. The light passes through the transparent electrode 35 and is extracted in a direction perpendicular to the group III-V compound semiconductor substrate 31.

FIG. 4 shows a typical example of the band structure in the vicinity of the active layer 33. The discontinuous value of the valence band edge 21 and the discontinuous value of the conduction band edge 22 at the interface between the active layer 33 and the 2-6 cladding layer 34 are large, and the diffusion potential of the pn junction is large. The leakage of electrons and holes is reduced, and the luminous efficiency is increased. Since the active layer 33 is made of a Group 3-5 compound semiconductor, the device life is long and the reliability is high.

[Embodiment 3] FIG. 5 is a perspective view of a semiconductor laser showing a third embodiment of the present invention, and FIG. 6 is a band structure diagram. In the first embodiment, the active layers 13 and 2-6
The third embodiment is the same as the first embodiment except that a 3-5 light guide layer 51 made of a p-type group 3-5 semiconductor and having a thickness of 200 nm or less is provided between the clad layer 14 and the clad layer 14.

As shown in FIG. 6, the 3-5 light guide layer 51
Has a larger forbidden band width than the active layer 13 and has an effect of confining carriers in the active layer 13 and an effect of adjusting the amount of light confinement. Since the 3-5 light guide layer 51 is thinner than the emission wavelength, light is distributed over the active layer 13 and the light guide layer 51. 2-6 The refractive index of the cladding layer 14 is 3-5.
Since the light is smaller than the cladding layer 12, the light tends to be biased toward the 3-5 cladding layer 12. However, the light bias can be adjusted by inserting the light guide layer 51.

[Embodiment 4] FIG. 7 is a perspective view of a semiconductor laser showing a fourth embodiment of the present invention, and FIG. 8 is a band structure diagram. In the first embodiment, the 3-5 cladding layer 1
A 3-5 light guide layer 71 made of an undoped group 3-5 semiconductor is provided between the active layer 13 and the active layer 13.
The second embodiment is the same as the first embodiment except that a 2-6 light guide layer 72 of 200 nm or less made of an undoped group 2-6 semiconductor is provided between the cladding layer 14 and the cladding layer 14.

The light guide layer 72 has an effect of confining carriers in the active layer 13 and an effect of adjusting the amount of light confinement. By controlling the refractive index and the layer thickness of the 3-5 light guide layer 71 and the light guide layer 72, the amount of light confined in the active layer 13 can be adjusted. To reduce the oscillation threshold current, the amount of light confinement is increased, and to increase the light output, the amount of light confinement is reduced so as to suppress end face degradation.

[Fifth Embodiment] FIG. 9 is a perspective view of a semiconductor laser according to a fifth embodiment. In the first embodiment, between the 2-6 cladding layer 14 and the p-electrode 15, the p-type
Embodiment 4 is the same as Embodiment 1 except that a contact layer 91 made of a Group 6 compound semiconductor is provided.

The contact layer 91 includes the p-electrode 15 and 2-6
This is provided to reduce the resistance between the cladding layer 14 and the cladding layer 14. In order to reduce the resistance, the doping concentration in the contact layer 91 may be increased to 1 × 1
It is preferably at least ¹⁸ cm ⁻³ . Contact layer 9
As a material for forming No. 1, ZnTe: N, ZnSeTe: N, BeTe:
N, BeSe: N, BeSeTe: N, ZnSe: N,
It is preferable to use ZnTe: P or the like.

When the junction between the 2-6 cladding layer 14 and the p-electrode 15 has Schottky properties, a material having an energy level intermediate between the two energy levels is used for the contact layer 91. A graded layer in which ZnSeTe: N, BeSeTe: N, or a component in these materials is gradually changed may be used.

In this embodiment, a p-type contact layer is used. However, if the 2-6 cladding layer is an n-type, ZnS
e: Cl, ZnCdSe: Cl, CdSe: Cl, Zn
An n-type group 2-6 compound semiconductor such as S: Cl and ZnSe: Ga may be used.

[Embodiment 6] FIG. 10 is a perspective view of a surface emitting semiconductor laser according to a sixth embodiment. In the second embodiment, the group III-V compound semiconductor substrates 31 and 3-5
Between the cladding layer 32 and the cladding layer 32, the thickness of each layer is
4, a p-type group 3-5 compound semiconductor 101a having a different composition
A 3-5 multilayer film 101 is formed by laminating a number of layers 101b, and a 2-6 multilayer film 102 is similarly formed by laminating a number of n-type 2-6 group compound semiconductors 102a and 102b on the 2-6 cladding layer 34. Is formed in the same manner as in the second embodiment except that a resonator structure is formed.

The light emitted from the active layer 33 is reflected by the 3-5 multilayer film 101 and the 2-6 multilayer film 102 to obtain laser oscillation. Two n-type 2-6 group compound semiconductors 102
Since the difference between the refractive indices a and 102b can be made large, the 2-6 multilayer film 102 having high reflectance and low resistance can be easily obtained.

P-type group III-V compound semiconductors 101a, 10a
A combination of GaAs and AlGaAs may be used for 1b, and n-type 2-6 group compound semiconductors 102a,
2b may be a combination of ZnSSe and MgZnSSe, a combination of ZnCdSe and MgZnCdSe, or the like.

[Seventh Embodiment] A seventh embodiment will be described with reference to FIG. Although the structure is the same as that of the first embodiment,
-Group 5 compound semiconductor substrate 11 is an n-type InP substrate;
A -5 cladding layer 12 is made of InP to which Si is added, the active layer 13 is made of InGaAsP, and a 2-6 cladding layer 14 is made of MgZnSeTe to which N is added, whereby a lattice-matched semiconductor laser can be obtained. The lattice matching reduces crystal defects, increases luminous efficiency, and improves reliability.

In this embodiment, the 3-5 cladding layer 12,
As the combination of the active layer 13 and the 2-6 cladding layer 14, a combination of InP, InGaAsP, and MgZnSeTe was used, but not limited thereto.
sP, MgZnCdSe combination, AlGaAs
s, GaAs, MgZnSSe combination, InG
A combination of aAlP, InGaP, MgZnSSe, a combination of InGaAlP, InGaP, BeZnSeTe, and the like may be used.

[Eighth Embodiment] FIG. 11 is a perspective view of a semiconductor laser showing an eighth embodiment. On a group III-V compound semiconductor substrate 111 made of n-type InP, a 3-5 cladding layer 112 made of n-type InP, a 3-5 light guide layer 113 made of n-type InGaAsP, and undoped InGaAs
Active layer 114 composed of P multiple quantum well, p-type InGaAs
After the 3-5 light guide layer 115 made of sP is formed by MOVPE, ZnCdSe made of N-doped ZnCdSe is used.
A cladding layer 116a and a MgZnSeTe cladding layer 116b made of N-doped MgZnSeTe were grown by MBE to form a 2-6 cladding layer 116. The lattices are all matched.

In the ZnCdSe cladding layer 116a in contact with the 3-5 light guide layer 115 made of p-type InGaAsP, the Group 6 element is only one kind of Se, and the Group 2 element is two kinds of Zn and Cd. The group 2 element is 3-
Since the coefficient of adhesion to the group V compound semiconductor does not change much, growth can be started with a composition proportional to the molecular beam intensity. On the other hand, group 6 elements are 3
Since the adhesion coefficient to the group -5 compound semiconductor is significantly different,
In the case of a mixed crystal containing two or more Group 2 elements, growth starts with a composition different from the molecular beam intensity. Therefore, the ZnCdSe cladding layer 11 grown on the 3-5 light guide layer 115
6a has no composition unevenness and is excellent in crystallinity.

On the ZnCdSe cladding layer 116a,
Since Se and Te adhere at a fixed ratio, an MgZnSeTe clad layer 116b having a controlled composition is obtained. M
When the gZnSeTe cladding layer 116b is grown directly on the 3-5 light guide layer 115, only a layer having very large compositional irregularity and poor crystallinity can be obtained. By introducing the ZnCdSe cladding layer 116a, the luminous efficiency of the semiconductor laser is greatly improved.

In this embodiment, the 3-5 light guide layer 11
5. As the combination of the cladding layer 116a and the cladding layer 116a, InGaAsP, ZnCdSe, Mg
The combination of ZnSeTe was used, but not limited to this.
A combination of aAs, BeZnSe, and MgZnSSe, a combination of GaAs, ZnSe, and MgZnSSe may be used.

[0037]

The semiconductor light emitting device of the present invention has high luminous efficiency by effectively confining light and carriers by using a group 2-6 compound semiconductor having a large forbidden band width as a part of the cladding layer. While the active layer is 3-5
By using a compound semiconductor, reliability such as temperature characteristics and electric characteristics is excellent. In addition, since a Group 2-6 compound semiconductor is formed on a 3-5 compound semiconductor, manufacturing is easy and a high yield can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a semiconductor laser according to an embodiment of the present invention.

FIG. 2 is a band structure diagram of an embodiment of the present invention.

FIG. 3 is a perspective view of a light emitting diode according to an embodiment of the present invention.

FIG. 4 is a band structure diagram of an embodiment of the present invention.

FIG. 5 is a perspective view of a semiconductor laser according to an embodiment of the present invention.

FIG. 6 is a band structure diagram of an embodiment of the present invention.

FIG. 7 is a perspective view of a semiconductor laser according to an embodiment of the present invention.

FIG. 8 is a band structure diagram according to an embodiment of the present invention.

FIG. 9 is a perspective view of a semiconductor laser according to an embodiment of the present invention.

FIG. 10 is a perspective view of a surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 11 is a perspective view of a semiconductor laser according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 3-5 group compound semiconductor substrate 12 3-5 clad layer 13 active layer 14 2-6 clad layer 15 p electrode 16 n electrode 17, 17b reflective mirror surface 21 valence band edge 22 conduction band edge 23 Fermi level 31 3- Group 5 compound semiconductor substrate 32 3-5 cladding layer 33 active layer 34 2-6 cladding layer 35 transparent electrode 36 p electrode 51 3-5 light guide layer 71 3-5 light guide layer 72 2-6 light guide layer 91 contact layer 101a, 101b p-type 3-5 group compound semiconductor 101 3-5 multilayer film 102a, 102b n-type 2-6 group compound semiconductor 102 2-6 multilayer film 111 3-5 group compound semiconductor substrate 112 3-5 cladding layer 113 3 -5 light guide layer 114 active layer 115 3-5 light guide layer 116a ZnCdSe cladding layer 116b MgZnSeTe cladding Layer 116 2-6 cladding layer

Claims (6)

[Claims] A first conductive type group III-V compound semiconductor substrate on a first conductive type group III-V compound semiconductor substrate;
A cladding layer 5, an active layer made of a group 3-5 compound semiconductor, and a 2-6 made of a second conductivity type group 2-6 compound semiconductor
A semiconductor light emitting device having a laminated structure including a cladding layer. 2. The semiconductor device according to claim 1, wherein the active layer and the 2-6 cladding layer are made of a Group 3-5 compound semiconductor or a Group 2-6 compound semiconductor having a larger forbidden band width than the active layer. 2. The light guide layer according to claim 1, further comprising a light guide layer which is thinner and whose conductivity type is an intrinsic type or a second conductivity type.
The semiconductor light-emitting device according to claim 1. 3. The semiconductor device according to claim 2, further comprising a contact layer made of a second conductivity type Group 2-6 compound semiconductor and having a higher impurity concentration than the 2-6 cladding layer, on the 2-6 cladding layer. 2. The semiconductor light emitting device according to 1. 4. The 3-5 group compound semiconductor substrate and 3-5
A reflective layer comprising a multilayered film of a Group 3-5 compound semiconductor between the clad layer and the clad layer;
2. The semiconductor light emitting device according to claim 1, further comprising: a reflection layer formed of a multilayer film of a group III compound semiconductor; and emitting light emitted from the active layer in a direction perpendicular to the substrate. 5. The semiconductor device according to claim 3, wherein
The layer made of a group 5 compound semiconductor and the layer made of a group 2-6 compound semiconductor have the same lattice length.
5. The semiconductor light emitting device according to any one of 4. 6. The 2-6 cladding layer comprises a multilayer,
The layer in contact with the layer made of a Group 3-5 compound semiconductor is a mixed crystal layer containing one kind of Group 6 element and one or more kinds of Group 2 elements. Semiconductor light emitting device.