CN1925180A - Epitaxial wafer for a semiconductor light emitting device, method for fabricating the same and semiconductor light emitting device - Google Patents

Abstract

The present invention provides an epitaxial wafer for a semiconductor light-emitting element that suppresses the diffusion of p-type dopants into a p-type cladding layer and an active layer and a manufacturing method thereof, and using the epitaxial wafer, stable high-power output operation and high-temperature operation can be performed and Semiconductor light emitting elements with high reliability. The structure of this epitaxial wafer for a semiconductor light-emitting element is that the following layers are sequentially stacked on an n-type substrate 1 made of GaAs: an n-type buffer layer 2 made of GaAs, an n-type buffer layer 3 made of GaInP, and an n-type buffer layer made of GaInP. n-type cladding layer 4 made of AlGaInP, non-doped guide layer 5 made of AlGaAs, active layer 6 made of AlGaAs/GaAs multiple quantum wells (MQW), p-type first cladding layer 7 made of AlGaInP , a p-type etching stopper layer 8 made of GaInP, a p-type second cladding layer 9 made of AlGaInP, a carbon-doped AlGaAs layer 10 (zinc diffusion suppressing layer) doped with carbon which is a characteristic part of the present invention, and A p-type intermediate layer 11 made of GaInP and a p-type cladding layer 12 made of GaAs.

Description

Epitaxial wafer for semiconductor light emitting element, manufacturing method thereof, and semiconductor light emitting element

technical field

The present invention relates to an epitaxial wafer for a semiconductor light-emitting element, a manufacturing method thereof, and a semiconductor light-emitting element, in particular to a semiconductor comprising an aluminum gallium indium phosphide (AlGaInP)-based material using zinc (Zn) or magnesium (Mg) as a p-type dopant An epitaxial wafer for light-emitting elements (light-emitting diodes, semiconductor lasers), a manufacturing method thereof, and a semiconductor light-emitting element manufactured using the epitaxial wafer.

Background technique

In recent years, the development of a high-density optical disk device using an AlGaInP-based visible light semiconductor laser among semiconductor lasers as a light source has been active. The Fabry-Perot laser diode (LD) used for this light source has a layered structure as follows, that is, on an n-type GaAs substrate, at least the following layers are sequentially stacked: n-type AlGaInP The cladding layer, as required, can have an n-type GaAs buffer layer between the two, and an n-type GaInP buffer layer if necessary; an active layer; a p-type AlGaInP cladding layer; a p-type GaAs covering (イツップ) layer, There may be a p-type GaInP intermediate layer interposed as required. In addition, if necessary, for etching control and refractive index design in the process, an epitaxial wafer having a structure in which a GaInP layer is inserted into a part of the p-type AlGaInP cladding layer is often used, and it is produced by metal organic vapor phase epitaxy (MOVPE method).

As a light source for reading and writing in high-density optical disc devices, stable high power output and high-temperature operation performance are required, so it is necessary to increase the carrier concentration of the p-type cladding layer. Zn or Mg is considered as a p-type dopant satisfying this requirement. Patent Document 1 describes an example of using Zn as a p-type dopant of a p-type cladding layer.

However, there is a problem in that the dopant diffuses from the p-type cladding layer to the active layer, and when the amount is large, it causes defects fatal to the function of the semiconductor laser device. Zn is relatively easy to diffuse, and Mg is not easy to diffuse. Therefore, recently, Mg, which has a diffusion constant smaller than that of Zn, tends to be used to form the p-type cladding layer. This is because Mg is more difficult to diffuse than Zn, and thus can increase the carrier concentration of the p-type cladding layer at a high concentration.

On the other hand, in view of the need to reduce the contact resistance of the electrodes as much as possible, the carrier concentration of the p-type cladding layer (contact layer) also needs to be relatively high. The p-type cladding layer is usually formed of gallium arsenide (GaAs). In addition, in view of the need for a carrier concentration higher than that of the cladding layer by one digit or more, Zn, which can be added at a high concentration, is used as a dopant (for example, refer to Patent Document 1).

In addition, there is also a proposal to make GaAs-based compound semiconductors mainly composed of GaAs-based compound semiconductors with a concentration of 5×10 ¹⁸ /cm ³ to 1×10 ²⁰ /cm between the p-type cladding layer and the active layer. ^3. Diffusion suppression layer of carbon (C) (for example, refer to Patent Document 2). C in the diffusion suppressing layer acts as a barrier layer, effectively suppressing the diffusion of Zn, Mg, etc. doped in the p-type cladding layer and active layer.

[Patent Document 1] JP-A-11-186665

[Patent Document 2] JP-A-2002-261321

Contents of the invention

As described in Patent Documents 1 and 2, conventionally, attention has to be paid to prevent the intrusion of Zn in the p-type cladding layer into the active layer. For example, Patent Document 2 describes that a diffusion suppressing layer containing carbon (C) for absorbing Zn diffused from the p-type cladding layer is interposed between the p-type cladding layer and the active layer, A layer that reduces the amount of Zn diffused into the active layer.

However, as described below, Zn in the p-type cladding layer should also be prevented from entering into the p-type cladding layer and the active layer.

Specifically, if a high concentration of Zn is added to the p-type cladding layer, Zn will continue to diffuse to the underlying layer during its epitaxial growth. When the underlying p-type cladding layer is doped with Zn, Zn in the p-type cladding layer is extruded and diffused into the active layer (extrusion diffusion). On the other hand, when the p-type cladding layer is doped with Mg, Zn in the p-type cladding layer diffuses into the active layer due to interdiffusion. In either case, there are disadvantages such as an increase in the half-value of the photoluminescence spectrum of the active layer (hereinafter referred to as a PL half-value) or a decrease in luminous intensity. That is, damage to the crystalline quality of the active layer due to diffusion of Zn causes an increase in threshold current or operating current and a decrease in reliability.

Therefore, the object of the present invention is to solve the above-mentioned problems, to provide an epitaxial wafer for a semiconductor light-emitting element that suppresses the diffusion of a p-type dopant to a p-type cladding layer and an active layer, and a method for manufacturing the same, and to use the epitaxial wafer to achieve stable It is a semiconductor light-emitting element with high power output operation and high temperature operation and high reliability.

In order to achieve the above objects, the present invention is constituted as follows.

That is, the epitaxial wafer for semiconductor light-emitting elements of the present invention is characterized in that, on an n-type substrate, at least an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type cladding layer are sequentially stacked, and the p-type cladding layer The p-type dopant is Zn, and a p-type AlGaAs layer doped with carbon is inserted between the p-type cladding layer and the p-type cladding layer.

In addition, the epitaxial wafer for a semiconductor light-emitting element of the present invention is characterized in that on an n-type substrate made of GaAs, at least one n-type cladding layer made of AlGaInP, an active layer, at least one layer made of The p-type cladding layer composed of AlGaInP and the p-type cladding layer composed of GaAs, the p-type dopant of the p-type cladding layer is Zn, and the p-type cladding layer and the p-type cladding layer are inserted and doped A p-type AlGaAs layer of carbon, and the bandgap wavelength of the p-type AlGaAs layer is longer than the bandgap wavelength of the p-type cladding layer.

In addition, the epitaxial wafer for a semiconductor light-emitting element of the present invention is characterized in that, on an n-type substrate, at least an n-type cladding layer, an active layer, a p-type cladding layer, a p-type intermediate layer, and a p-type cladding layer are sequentially stacked. , the p-type dopant of the p-type cladding layer is Zn, and a p-type AlGaAs layer doped with carbon is inserted between the p-type cladding layer and the p-type intermediate layer.

In addition, the epitaxial wafer for semiconductor light-emitting element of the present invention is characterized in that, on an n-type substrate made of GaAs, at least one n-type cladding layer made of AlGaInP, an active layer, at least one layer made of AlGaInP A p-type cladding layer composed of at least one p-type intermediate layer made of GaInP or AlGaInP and a p-type cladding layer made of GaAs, the p-type dopant of the p-type cladding layer is Zn, and in the p-type cladding layer A p-type AlGaAs layer doped with carbon is inserted between the cladding layer and the p-type intermediate layer, and the bandgap wavelength of the p-type AlGaAs layer is longer than that of the p-type cladding layer, which is longer than that of the p-type intermediate layer. to be short.

The p-type dopant of the above-mentioned p-type cladding layer may be Zn or Mg.

In addition, the epitaxial wafer for a semiconductor light-emitting element of the present invention is characterized in that on an n-type substrate, at least an n-type cladding layer, an active layer, a p-type first cladding layer, a p-type etching stop layer, a p Type 2 cladding layer, p-type intermediate layer and p-type cladding layer, the p-type dopant of p-type cladding layer is Zn, insert doping between the p-type 2nd cladding layer and p-type intermediate layer Carbon p-type AlGaAs layer.

In addition, the epitaxial wafer for a semiconductor light emitting element of the present invention is characterized in that on an n-type substrate made of GaAs, at least an n-type cladding layer made of AlGaInP, an active layer, and a p-type third layer made of AlGaInP are sequentially stacked. 1 cladding layer, p-type etch stop layer, p-type second cladding layer made of AlGaInP, p-type intermediate layer made of GaInP, and p-type cladding layer made of GaAs, p-type doping of p-type cladding layer The agent is Zn, and a p-type AlGaAs layer doped with carbon is inserted between the p-type second cladding layer and the p-type intermediate layer.

The p-type etching stop layer may be at least one layer made of GaInP or AlGaInP.

The p-type dopant of the above-mentioned p-type second cladding layer may be Zn or Mg.

In addition, the method for manufacturing an epitaxial wafer for a semiconductor light-emitting element according to the present invention is characterized in that the carbon doping of the p-type AlGaAs layer doped with carbon is achieved by adjusting the V/III ratio between the III-group raw material and the V-group raw material. The ratio is performed by self-doping of organometallic starting materials.

In addition, the method for manufacturing an epitaxial wafer for a semiconductor light-emitting element according to the present invention is characterized in that the carbon doping of the p-type AlGaAs layer doped with carbon is performed by self-doping of an organic metal raw material by adjusting the growth temperature. .

Furthermore, a semiconductor light emitting element can also be produced using the above-mentioned epitaxial wafer for a semiconductor light emitting element.

The inventors have found that: (1) when an AlGaAs layer is inserted between the p-type cladding layer and the p-type cladding layer, Zn in the p-type cladding layer does not diffuse into the p-type cladding layer at all; Regardless of whether the p-type dopant of the cladding layer is Zn or Mg, the function of preventing Zn diffusion of the AlGaAs layer can be effectively exerted.

The present invention is completed based on the inventor's above knowledge. The structure of the epitaxial wafer for semiconductor light-emitting element of the present invention is that on an n-type substrate, at least an n-type cladding layer, an active layer, and a p-type cladding layer are sequentially stacked. layer, p-type cladding layer (contact layer), the p-type dopant of the uppermost p-type cladding layer is Zn, and an AlGaAs layer is inserted between the p-type cladding layer and the p-type cladding layer.

In addition, the structure of the epitaxial wafer for semiconductor light-emitting element of the present invention is that on an n-type substrate, at least an n-type cladding layer, an active layer, a p-type cladding layer, a p-type intermediate layer, and a p-type cladding layer ( contact layer), the p-type dopant of the uppermost p-type cladding layer is Zn, and an AlGaAs layer is inserted between the p-type cladding layer and the p-type intermediate layer.

When such a structure is formed, since the AlGaAs layer suppresses the diffusion of Zn doped in the p-type cladding layer and plays the role of a zinc diffusion inhibiting layer, Zn will not substantially flow from the AlGaAs layer to the p-type cladding layer. Diffusion on the cladding side and the active layer side. As a result, conventional problems such as deterioration of light emission characteristics of the active layer and device lifetime can be solved.

The above-mentioned function of preventing diffusion is caused by the fact that the inserted layer is an AlGaAs layer. If only for this function, it is not necessary to be carbon-doped p-type. However, in actual production of an epitaxial wafer for a light-emitting element, it is necessary to form a low-resistance layer sufficiently so that the AlGaAs layer does not become a resistance component of the element. Therefore, the present invention requires a p-type AlGaAs layer doped with carbon having a small diffusion coefficient.

In addition, since this structure can prevent Zn doped in the p-type cladding layer from diffusing, it is possible to maintain Zn in the p-type cladding layer at a high concentration and realize a low resistance of the contact resistance between the cladding layer and the electrode. As a result, it is possible to Reduce the forward operating voltage of the component.

In this way, in order to prevent Zn doped in the cover layer from diffusing, between the p-type clad layer and the p-type intermediate layer (or interface), or between the p-type clad layer and the p-type cover layer (or interface) Inserting an AlGaAs layer and forming a carbon-doped p-type layer so that the AlGaAs layer does not function as a resistance layer has not been thought of before to eliminate an increase in the forward operating voltage of a semiconductor light emitting element.

Regardless of which of Zn and Mg the p-type dopant of the p-type cladding layer is, the above-mentioned function of preventing Zn diffusion of the AlGaAs layer can be effectively exerted. Therefore, the scope of application of the present invention is very wide, even in the epitaxial wafer for semiconductor light-emitting element that is made by epitaxially growing a compound semiconductor of AlGaInP-based material on a substrate made of GaAs and mainly using Zn or Mg as a p-type dopant , as long as a carbon-doped p-type AlGaAs layer is inserted between the p-type cladding layer and the p-type intermediate layer (or interface), the effect of inhibiting Zn diffusion expected by the present invention can be obtained.

According to the present invention, a structure is formed in which a p-type AlGaAs layer doped with carbon is inserted between (or interface) between the p-type cladding layer and the p-type cladding layer or p-type intermediate layer, and the AlGaAs layer functions to suppress the Since Zn diffuses as a zinc diffusion suppressing layer, Zn, which is a p-type dopant in the p-type cladding layer, hardly diffuses from the AlGaAs layer to the p-type cladding layer side or the active layer side. That is, the diffusion of Zn in the p-type cladding layer doped at a high concentration into the p-type cladding layer, especially the active layer can be extremely effectively suppressed, so that the light-emitting characteristics of the active layer and the device life are not deteriorated. As a result, it is possible to provide epitaxial wafers for semiconductor light-emitting elements that can be doped to a carrier concentration that is sufficiently low in contact resistance in the cladding layer, and that are suitable for producing light-emitting elements such as red semiconductor lasers that are excellent in high-power output and high-temperature characteristics and have high reliability. .

Incidentally, when comparing the diffusion of dopants from the p-type cladding layer into the active layer with the diffusion of Zn from the p-type cladding layer into the active layer, since the p-type cladding layer has a high concentration of Zn, it is actually Zn diffusion from the p-type cladding layer has a large influence on device characteristics. Therefore, in addition to suppressing the diffusion of dopants from the p-type cladding layer into the active layer, the present invention can also effectively produce light-emitting elements such as red semiconductor lasers with excellent high-power output and high-temperature characteristics and high reliability.

Description of drawings

FIG. 1 is a schematic cross-sectional view showing an epitaxial wafer for a semiconductor light emitting element according to a first embodiment.

2 is a schematic cross-sectional view showing an epitaxial wafer for a semiconductor light emitting element according to a second embodiment.

FIG. 3 is a diagram showing a comparison of SIMS analysis results of an epitaxial wafer for a semiconductor light emitting element according to Example 1 having a zinc diffusion preventing layer and a conventional epitaxial wafer for a semiconductor light emitting element.

4 is a graph showing the results of SIMS analysis of an epitaxial wafer for a semiconductor light emitting element according to Example 2 having a zinc diffusion preventing layer.

Symbol Description

1 n-type substrate

2 n-type buffer layer (Si doped)

3 n-type buffer layer (Si doped)

4 n-type cladding layer (Si doped)

5 non-doped guide layer

6 active layer

7 p-type first cladding layer (Zn doped)

8 p-type etch stop layer (Zn doped)

9 p-type second cladding layer (Zn doped)

10 carbon-doped AlGaAs layer (zinc diffusion suppression layer)

11 p-type intermediate layer (Zn doped)

12 p-type cladding layer (Zn doped)

13 n-type substrate

14 n-type buffer layer (Si doped)

15 n-type buffer layer (Si doped)

16 n-type cladding layer (Si doped)

17 Non-doped guide layer

18 active layers

19 p-type first cladding layer (Mg doped)

20 p-type etch stop layer (Mg doped)

21 p-type second cladding layer (Mg doped)

22 carbon-doped AlGaAs layer (zinc diffusion suppression layer)

23 p-type interlayer (Mg doped)

24 p-type cladding layer (Zn doped)

Detailed ways

Hereinafter, the present invention will be described based on the illustrated embodiments.

first embodiment

The epitaxial wafer for semiconductor light-emitting elements (LD) shown in FIG. 1 has a structure in which the following layers are sequentially stacked on an n-type substrate 1 made of GaAs: an n-type buffer layer 2 made of GaAs, a layer made of GaInP The n-type buffer layer 3 composed of AlGaInP, the n-type cladding layer 4 composed of AlGaInP, the non-doped guide layer 5 composed of AlGaAs, the active layer 6 composed of AlGaAs/GaAs multiple quantum wells (MQW), and the active layer 6 composed of AlGaInP p-type first cladding layer 7, p-type etch stop layer 8 made of GaInP, p-type second cladding layer 9 made of AlGaInP, carbon-doped AlGaAs layer doped with carbon which is a characteristic part of the present invention 10 (zinc diffusion suppressing layer), a p-type intermediate layer 11 made of GaInP, and a p-type cladding layer 12 made of GaAs. The p-type dopant doped in the p-type first cladding layer 7 , the p-type second cladding layer 9 , the p-type etch stop layer 8 and the p-type intermediate layer 11 is Zn.

As mentioned above, setting the Zn-doped p-type intermediate layer 11 is used to reduce the interface between the Zn-doped p-type second cladding layer 9 and the Zn-doped p-type GaAs cladding layer 12 due to the discontinuity of the band gap. resistance component.

The aluminum composition of the p-type carbon-doped AlGaAs layer 10 (zinc diffusion preventing layer) doped with carbon has a bandgap wavelength longer than that of the p-type second cladding layer 9 and longer than that of the p-type intermediate layer 11. The bandgap wavelength is shorter. This is also for reducing the resistance component of the interface between the p-type second cladding layer 9 , the carbon-doped AlGaAs layer 10 , and the p-type intermediate layer 11 due to the discontinuity of the band gap.

When the structure shown in FIG. 1 above is formed, the carbon-doped AlGaAs layer 10 acts as a zinc diffusion suppressing layer that suppresses the diffusion of Zn doped in the p-type cladding layer 12, and therefore, Zn will not substantially escape from the AlGaAs. layer diffused towards the active layer side. Regardless of which of Zn and Mg is the p-type dopant of the p-type cladding layer, the carbon-doped AlGaAs layer can effectively exert the function of inhibiting Zn diffusion. In addition, due to the doping of carbon, there is no resistance to increase the forward operating voltage of the semiconductor light emitting element.

Doping carbon into the above-mentioned AlGaAs layer inserted between the p-type cladding layer and the p-type intermediate layer is not a method of intentionally adding impurities, but a method of adjusting the V/III ratio of the III-group raw material and the V-group raw material. ratio for self-doping. That is, the amount of carbon doping with respect to the carbon-doped AlGaAs layer 10 can be controlled and set by adjusting the V/III ratio of the group III material to the group V material.

2nd embodiment

On the other hand, the epitaxial wafer for a semiconductor light emitting element (LD) shown in FIG. 2 has a structure in which the following layers are sequentially stacked on an n-type substrate 13 made of GaAs: n-type buffer layer made of GaAs 14. An n-type buffer layer 15 made of GaInP, an n-type cladding layer 16 made of AlGaInP, an undoped guiding layer 17 made of AlGaInP, an active layer 18 made of multiple quantum wells (MQW), and an active layer 18 made of AlGaInP p-type first cladding layer 19, a p-type etch stop layer 20 made of GaInP, a p-type second cladding layer 21 made of AlGaInP, a carbon-doped AlGaAs layer 22 which is a characteristic part of the present invention, and an aluminum layer laminated with The p-type intermediate layer 23 having a structure of a plurality of p-type AlGaInP thin films and p-type GaInP thin films having different compositions, and the p-type cladding layer 24 made of GaAs. The p-type dopant doped in the p-type first cladding layer 19 , the p-type second cladding layer 21 , the p-type etching stopper layer 20 , and the p-type intermediate layer 23 is Mg.

As mentioned above, setting the Mg-doped p-type intermediate layer 23 is used to reduce the interface between the Mg-doped p-type second cladding layer 21 and the Zn-doped p-type GaAs cladding layer 24 due to the discontinuity of the band gap. resistance component.

The aluminum composition of the p-type carbon-doped AlGaAs layer 22 (zinc diffusion prevention layer) doped with carbon has a bandgap wavelength longer than that of the p-type second cladding layer 21 and longer than that of the p-type intermediate layer 23. The layer with the shortest bandgap wavelength has a shorter bandgap wavelength. This is also for reducing the resistance component of the interface between the p-type second cladding layer 21 , the carbon-doped AlGaAs layer 22 , and the p-type intermediate layer 23 due to the discontinuity of the band gap.

When the structure shown in FIG. 2 above is formed, the carbon-doped AlGaAs layer 22 functions as a zinc diffusion preventing layer for preventing Zn doped into the p-type cladding layer 24 from diffusing, and therefore, Zn will not substantially escape from the AlGaAs. layer diffuses toward the p-type cladding layer side. Regardless of which of Zn and Mg is the p-type dopant of the p-type cladding layer, the function of preventing Zn diffusion of the carbon-doped AlGaAs layer can be effectively exerted. In addition, due to the doping of carbon, there is no resistance to increase the forward operating voltage of the semiconductor light emitting element.

Doping carbon into the above-mentioned AlGaAs layer inserted between the p-type cladding layer and the p-type intermediate layer is not a method of intentionally adding impurities, but by adjusting the V/III ratio of the III-group raw material to the V-group raw material for self-doping. That is to say, the carbon doping amount relative to the carbon-doped AlGaAs layer 22 can be controlled and set by adjusting the V/III ratio of the group III material to the group V material.

Example 1

As Example 1, an epitaxial wafer for a semiconductor light emitting element shown in FIG. 1 was prepared.

As shown in Fig. 1, on an n-type GaAs substrate 1, a Si-doped n-type buffer layer 2 composed of GaAs, and a Si-doped n-type buffer layer composed of Ga _0.5 In _0.5 P lattice-matched to it are epitaxially grown in sequence. Layer 3, a Si-doped n-type cladding layer 4 composed of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, on which a non-doped guiding layer 5 composed of Al _0.34 Ga _0.66 As, including Al _0.34 The non-doped barrier layer composed of Ga _0.66 As and the multiple quantum well (MQW) active layer 6 composed of the non-doped well layer composed of Al _0.11 Ga _0.89 As, and the active layer 6 composed of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P Zn-doped p-type first cladding layer 7, Zn-doped p-type etch stop layer 8 composed of Ga _0.5 In _0.5 P, Zn-doped p-type second cladding layer composed of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding 9.

Subsequently, a carbon-doped Al _0.85 Ga _0.15 As layer 10 as a zinc diffusion suppressing layer, a Zn-doped p-type intermediate layer 11 composed of Ga _0.5 In _0.5 P, and a Zn-doped p-type intermediate layer 11 composed of GaAs, which are characteristic parts of the present invention, are sequentially grown thereon. The Zn-doped p-type cladding layer 12. Among them, the aluminum composition of the carbon-doped Al _0.85 Ga _0.15 As layer 10 is 0.85, the thickness is 40nm, and the self-doping carrier concentration of carbon (C) formed by adjusting the V/III ratio is 8×10 ¹⁷ /cm ³ . In addition, the thickness of the Zn-doped p-type intermediate layer 11 composed of Ga _0.5 In _0.5 P is 50 nm, and the carrier concentration is 2×10 ¹⁸ /cm ³ ; the thickness of the Zn-doped p-type cladding layer 12 is 450 nm, carrying The carrier concentration was 1×10 ¹⁹ /cm ³ .

The distribution of Zn in the epitaxial wafer for semiconductor light-emitting element having the layered structure of this example (the present invention) was investigated by SIMS analysis, and the results are shown in FIG. 3 . In the figure, the curve 25 is the distribution curve of Zn in the structure shown in FIG. 1 (Example 1), and the curve 26 is made for comparison, except that the carbon-doped Al _0.85 Ga _0.15 As layer that becomes the zinc diffusion suppression layer is not inserted. 10 Distribution curves of Zn for cases with exactly the same structure. In addition, in FIG. 3 , in order to clearly show the difference between Example 1 and the comparative example, the active layer side is shown enlarged from the etching stopper layer.

In the case of the comparative example (curve 26), the level of Zn in the cladding layer increased, and it was also clearly seen that Zn entered the active layer. On the other hand, in the case of Example 1 (curve 25), it was found that the diffusion of Zn into the active layer was at a level that did not cause any problems.

In addition, the device characteristics of the infrared high-power output semiconductor laser (infrared side of the monolithic dual-wavelength laser) fabricated using the epitaxial wafer for semiconductor light-emitting element of the first embodiment are also very good.

Example 2

As Example 2, an epitaxial wafer for a semiconductor light emitting element shown in FIG. 2 was prepared.

As shown in FIG. 2 , on an n-type substrate 13 made of GaAs, a Si-doped n-type buffer layer 14 made of GaAs and a Si-doped n-buffer layer made of GaInP that match its lattice are epitaxially grown in sequence. 15. A Si-doped n-type cladding layer 16 composed of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, on which a non-doped guide layer 17 composed of (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P is sequentially grown, A multiple quantum well (MQW) active layer 18 comprising an undoped (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P barrier layer and a strained GaInP well layer, and a Mg-doped (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P p-type first cladding layer 19, Mg-doped p-type etch stop layer 20 made of Ga _0.5 In _0.5 P, Mg-doped p-type second cladding layer made of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P twenty one.

Subsequently, a carbon-doped Al _0.85 Ga _0.15 As layer 22, a Mg-doped Ga _0.5 In _0.5 P intermediate layer 23, and a Zn-doped p Type cover layer 24. Among them, the aluminum composition of carbon-doped Al _0.85 Ga _0.15 As layer 22 is 0.85, the thickness is 35nm, and the self-doping carrier concentration of carbon formed by adjusting the V/III ratio is 1.1×10 ¹⁸ /cm ³ The thickness of the Mg-doped Ga _0.5 In _0.5 P intermediate layer 23 is 35nm, and the carrier concentration is 2.5×10 ¹⁸ /cm ³ ; the thickness of the Zn-doped p-type cladding layer 24 made of GaAs is 200nm, and the carrier The concentration is 2.5×10 ¹⁹ /cm ³ .

The distribution of Zn and Mg of the epitaxial wafer for semiconductor light-emitting element having the layered structure of this example (the present invention) was investigated by SIMS analysis, and the results are shown in FIG. 4 .

From this result, it can be seen that Zn hardly diffused from the Mg-doped p-type second cladding layer 21 to the active layer side.

In addition, the device characteristics of the infrared high-power output semiconductor laser manufactured using the epitaxial wafer for semiconductor light emitting device of the second embodiment are also very good.

Claims (12)

1. An epitaxial wafer for a semiconductor light-emitting element, at least sequentially stacking an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type cladding layer on an n-type substrate, and the p-type dopant of the p-type cladding layer is Zn , characterized in that a p-type AlGaAs layer doped with carbon is inserted between the p-type cladding layer and the p-type cladding layer. 2. Epitaxial wafers for semiconductor light-emitting elements, on an n-type substrate composed of GaAs, at least one n-type cladding layer composed of AlGaInP, an active layer, and at least one p-type cladding layer composed of AlGaInP are sequentially stacked And a p-type cladding layer made of GaAs, the p-type dopant of the p-type cladding layer is Zn, characterized in that a p-type doped carbon is inserted between the p-type cladding layer and the p-type cladding layer AlGaAs layer, and the bandgap wavelength of the p-type AlGaAs layer is longer than the bandgap wavelength of the p-type cladding layer. 3. An epitaxial wafer for a semiconductor light-emitting element, at least sequentially stacking an n-type cladding layer, an active layer, a p-type cladding layer, a p-type intermediate layer, and a p-type cladding layer on an n-type substrate. The dopant is Zn, and it is characterized in that a p-type AlGaAs layer doped with carbon is inserted between the p-type cladding layer and the p-type intermediate layer. 4. Epitaxial wafers for semiconductor light-emitting elements, on an n-type substrate composed of GaAs, at least one n-type cladding layer composed of AlGaInP, an active layer, and at least one p-type cladding layer composed of AlGaInP are sequentially stacked , at least one p-type intermediate layer made of GaInP or AlGaInP and a p-type cladding layer made of GaAs, the p-type dopant of the p-type cladding layer is Zn, characterized in that, in the p-type cladding layer and A carbon-doped p-type AlGaAs layer is inserted between the p-type intermediate layers, and the bandgap wavelength of the p-type AlGaAs layer is longer than the bandgap wavelength of the p-type cladding layer and longer than the bandgap wavelength of the p-type intermediate layer. to be short. 5 . The epitaxial wafer for a semiconductor light emitting element according to claim 1 , wherein the p-type dopant of the p-type cladding layer is Zn or Mg. 6. An epitaxial wafer for a semiconductor light-emitting element, on an n-type substrate, at least an n-type cladding layer, an active layer, a p-type first cladding layer, a p-type etching stop layer, a p-type second cladding layer, The p-type intermediate layer and the p-type cladding layer, the p-type dopant of the p-type cladding layer is Zn, and it is characterized in that, between the p-type second cladding layer and the p-type intermediate layer, carbon-doped p-type AlGaAs layer. 7. An epitaxial wafer for a semiconductor light-emitting element, on an n-type substrate made of GaAs, at least an n-type cladding layer made of AlGaInP, an active layer, a p-type first cladding layer made of AlGaInP, a p-type An etch stop layer, a p-type second cladding layer made of AlGaInP, a p-type intermediate layer made of GaInP, and a p-type cladding layer made of GaAs, the p-type dopant of the p-type cladding layer is Zn, characterized in that , a carbon-doped p-type AlGaAs layer is inserted between the p-type second cladding layer and the p-type intermediate layer. 8. The epitaxial wafer for semiconductor light-emitting elements according to claim 6 or 7, characterized in that, the p-type etching stop layer is composed of at least one layer of GaInP or AlGaInP. 9. The epitaxial wafer for semiconductor light-emitting element according to claim 6 or 7, wherein the p-type dopant of the p-type second cladding layer is Zn or Mg. 10. The method for manufacturing an epitaxial wafer for a semiconductor light-emitting element according to any one of claims 1 to 4, 6, and 7, wherein the carbon doping of the p-type AlGaAs layer doped with carbon is achieved by Adjustment of the V/III ratio of the group III raw material to the group V raw material is performed by self-doping of the organometallic raw material. 11. The method for manufacturing an epitaxial wafer for a semiconductor light-emitting element according to any one of claims 1 to 4, 6, and 7, wherein the carbon doping of the p-type AlGaAs layer doped with carbon is achieved by Adjusting the growth temperature is carried out by self-doping of organometallic raw materials. 12. A semiconductor light emitting element, characterized in that it is manufactured using the epitaxial wafer for a semiconductor light emitting element according to any one of claims 1 to 9.

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