JPH05235469A - Surface-emission type semiconductor laser apparatus - Google Patents

Abstract

PURPOSE:To provide a surface-emission type semiconductor laser apparatus with its construction where a current is constricted by a current stopping layer and a cladding layer, wherein even the thinner cladding layer ensures a satisfactory current constricting effect. CONSTITUTION:There are formed on a p-type GaAlAs cladding layer 5 a first current stopping layer 6 comprising a p-type GaAs layer 6a and a p-type GaAlAs layer 6b arranged in this order, and a second current stopping layer 7 comprising an n-type GaAlAs layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-emitting type semiconductor laser device in which a direction perpendicular to a substrate surface is a resonance direction and a light output is taken out in this direction.

[0002]

2. Description of the Related Art Recently, with the demand for integration of electronic devices, etc., a semiconductor layer is epitaxially grown on a substrate,
A surface-emitting type semiconductor laser device has been developed that takes out laser light from a direction perpendicular to the substrate surface.

This surface-emitting type semiconductor laser device is, for example, the proceedings (No. 3) of the 52nd Annual Meeting of the Applied Physics Society of Japan.
, Pp. 1024, 11p-ZM-1.
FIG. 3 is a sectional view of such a semiconductor laser device.

In the figure, 21 is a substrate (n-type GaAs). A semiconductor multilayer film reflecting mirror (n-type Ga) is formed on the substrate 21.
_0.9 Al _0.1 As / AlAs plural pairs 22, first clad layer (n-type Ga _0.6 Al _0.4 As) 23, active layer (p-type GaAs) 24, second clad layer (p-type Ga _0.6 Al _0.4)
As) 25 is laminated in this order. An n-type GaAs layer 26 and an n-type Ga _0.9 A are formed on the second cladding layer 25.
A current blocking layer composed of the _0.1 As layer 27 is formed in this order. Then, an opening is made in the substantially central portion of the current blocking layer, and the second cladding layer 25 is partially exposed.

Then, the exposed second cladding layer 25
A current injection layer (p-type Ga _0.6
Al _0.4 As) 28 is formed, and the current injection layer 2
A dielectric multilayer reflecting mirror 29 (a plurality of pairs of SiO ₂ / TiO ₂ ) and a contact layer (p-type GaAs) 30 are formed on the dielectric layer 8 so as to surround the dielectric multilayer reflecting mirror 29.

A p-type electrode (Au / Cr) 31 is formed on the upper surface of the contact layer 30, and n is formed on the lower surface of the substrate 21.
A mold electrode (Au / Sn) 32 is formed.

[0007]

In the surface-emitting type semiconductor laser device, it is effective to reduce the layer thickness of the second cladding layer 25 in order to improve the characteristics such as the oscillation threshold current, and particularly, the current blocking layer. It is desirable to reduce the layer thickness of the second clad layer 25 in order to prevent the current confined in the second clad layer from spreading.

However, if the layer thickness of the second cladding layer 25 is smaller than about 1 μm, the pn reverse bias withstand voltage characteristics of the second cladding layer 25 and the current blocking layer deteriorate, and the current blocking layer becomes poor. There is a problem that the leak current passing through the gate increases.

The present invention has been made in view of the above problems, and provides a semiconductor laser device in which the current blocking effect is prevented from being deteriorated even when the thickness of the cladding layer below the current blocking layer is small. The purpose is to do.

[0010]

A surface-emitting type semiconductor laser device of the present invention has a double heterostructure portion in which a first and a second cladding layers sandwich an active layer on a GaAs substrate,
A current blocking layer having a current passage portion is provided on the second cladding layer, and the current blocking layer has a first conductivity type same as that of the second cladding layer.
It is characterized in that the current blocking layer and the second current blocking layer of the opposite conductivity type are formed in this order.

In particular, the active layer is GaAs or GaA.
Further, the first current blocking layer is characterized in that the GaAs layer and the GaAlAs layer are laminated in this order.

[0012]

The first current blocking layer has the same conductivity type as that of the clad layer underlying the current blocking layer, and the second current blocking layer has a conductivity type opposite to the first current blocking layer.
Since the current blocking layer is used, even if the thickness of the clad layer below the current blocking layer is small, good pn reverse bias characteristics due to the clad layer and the first current blocking layer and the second current blocking layer are achieved. A large current constriction effect can be obtained.

In particular, the active layer is GaAs or GaA.
It is preferable that the first current blocking layer is GAs.
When the aAs layer and the GaAlAs layer are laminated in this order, a highly accurate current blocking layer can be easily formed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A surface emitting semiconductor laser device according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a cross-sectional view of the semiconductor laser device of this embodiment.

In the figure, 1 is a substrate (n-type GaAs).
On the upper surface of the substrate 1, a semiconductor multilayer film reflecting mirror (n-type Ga
25 pairs of _0.8 Al _0.2 As / AlAs; where the layer thickness of each layer is oscillation wavelength / 4 / refractive index) 2 is formed, and the first clad layer having a layer thickness of 0.3 μm is formed on the reflecting mirror 2. (N-type Ga _0.6 Al _0.4 As) 3, 0.5 μm thick active layer (p
A double heterostructure portion 100 is formed by stacking a type Ga _0.87 Al _0.13 As) 4 and a second clad layer (p type Ga _0.6 Al _0.4 As) 5 having a layer thickness of 0.3 μm in this order.

A layer thickness of 0.3 is formed on the second cladding layer 5.
μm p-type GaAs layer 6a and 0.3 μm-thick p-type Ga
A first current blocking layer 6 in which an AlAs layer (for example, Ga _0.9 Al _0.1 As) 6b is stacked in this order, and a layer thickness of 1 μm
The m second current blocking layer (n-type Ga _0.9 Al _0.1 As) 7 is formed in this order to form the current blocking layer 9 having the concave portion 17 serving as a current passage portion.

A current injection layer (p-type Ga _0.6 Al _0.4 As) 10 is formed on the current blocking layer 9 and in the recess 17, and the current injection layer 10 faces the recess 17. A dielectric multilayer film reflecting mirror 11 (4 pairs of SiO ₂ / TiO ₂ ) is formed, and a contact layer (p-type GaAs) 12 having a layer thickness of 0.8 μm is formed on the remaining portion. A p-type electrode (Au / Cr) 13 is formed on the contact layer 12 so as to surround the dielectric multilayer film reflection mirror 11, and the substrate 1
An n-type electrode (Au / Sn) 14 is formed on the lower surface of the.

Next, an example of a method of manufacturing such a semiconductor laser device will be described. The same parts as those in FIG. 1 are designated by the same reference numerals.

First, as shown in FIG. 2A, first,
After the n-type GaAs substrate 1 is prepared, the semiconductor multilayer film reflecting mirror 2 and the first cladding layer are formed on the upper surface of the substrate 1 by using a metal organic chemical vapor deposition method (MOCVD method) or a molecular beam epitaxial method (MBE method). 3, the active layer 4, the second cladding layer 5,
The p-type GaAs layer 6a and the p-type GaAlAs layer (for example, G
The current blocking layer 9 is formed by forming the first current blocking layer 6 and the second current blocking layer 7 made of a _0.9 Al _0.1 As) 6b in this order.

Next, as shown in FIG. 2B, the second
By using photolithography technology or the like on the current blocking layer 7,
For example, a resist pattern film 18 having a window with a diameter of 10 μm
Then, the second current blocking layer 7 and the first current blocking layer 6 are etched with an ammonia-based etching solution using the resist pattern film 18 as a mask, and the p-type GaAs layer 6a of the first current blocking layer 6 is etched. Then, the resist pattern film 18 is removed. Here, the p-type Ga under the recess 17a is
The reason why the As layer 6a is not removed is GaA having a high Al component ratio.
This is to prevent the surface of the second clad layer 5 made of lAs from being oxidized in the atmosphere and preventing the crystal growth on the second clad layer 5 by the LPE method which is a later step.

Subsequently, as shown in FIG. 2C, GaA
p-type Ga under the recess 17a using s-melt
After the As layer 6a is removed by meltback to form the recess 17, the liquid phase epitaxial method (LPE method) is used to form the current injection layer 10 on the second current blocking layer 7 and in the recess 17, and then the current is injected. The contact layer 12 is formed on the injection layer 10.

Next, as shown in FIG. 1 which is a completed drawing, the recess 17 of the contact layer 12 is removed to expose the current injection layer 10, and the exposed current injection layer 10 is subjected to electron beam evaporation. The dielectric multilayer reflecting mirror 11 is formed by a method or the like. Then, the dielectric multilayer reflecting mirror 1 is formed by a vapor deposition method or the like.
The p-type electrode 13 is formed so as to surround 1. Then, after adjusting the thickness of the substrate 1, the n-type electrode 14 is formed on the lower surface of the substrate 1 by vapor deposition.

In this surface-emitting type semiconductor laser device, even when the layer thickness of the second cladding layer 5 on the active layer 4 is small, it is the same as the second cladding layer 5 on the second cladding layer 5. Since the conductivity type first current blocking layer 6 is formed, the pn reverse bias by the second cladding layer 5 and the first current blocking layer 6 and the second current blocking layer 7 having a conductivity type opposite to those of the second cladding layer 5 and the first current blocking layer 6. The characteristics are improved, and the current is prevented from leaking from the current blocking layer 9.

A single Ga layer is used as the first current blocking layer.
As layer or GaAlAs layer may be used, but GaAs
The layer is easy to melt back with GaAs melt,
Further, as described above, it is preferable to use a layer in which the GaAs layer and the GaAlAs layer are laminated in this order because the GaAs layer melted with GaAs can be thinned and the width of the recess of the current blocking layer can be suppressed. ..

Although the n-type GaAs substrate is used in the above embodiment, a p-type GaAs substrate may be used. However, in this case, the first and second current blocking layers and the like also need to have opposite conductivity types. In addition, instead of GaAlAs in the active layer, GaA
s may be used. Further, the second current blocking layer may be GaAs, but as described above, GaAlAs is Ga.
This is desirable because the width of the recess does not expand due to As meltback.

Further, although the GaAlAs semiconductor laser device has been described in the above embodiment, the present invention can be applied to other devices such as InP semiconductor laser device. Furthermore, the present invention is not limited to the structure of this embodiment, and may have a structure in which light is extracted from the direction opposite to the crystal growth direction, for example, and can be appropriately changed.

[0027]

The surface-emitting type semiconductor laser device of the present invention comprises:
Since the current blocking layer is composed of a first current blocking layer having the same conductivity type as the cladding layer below the current blocking layer and a second current blocking layer having a conductivity type opposite to these, the cladding below the current blocking layer. Even if the layer thickness is small, a good current confinement effect can be obtained.

Particularly, when the first current blocking layer is a GaAs layer and a GaAlAs layer stacked in this order, a highly accurate current blocking layer can be easily formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a surface emitting semiconductor laser device according to an embodiment of the present invention.

FIG. 2 is a process drawing showing a manufacturing process of a surface emitting semiconductor laser device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional surface emitting semiconductor laser device.

[Explanation of symbols]

 1 GaAs Substrate 3 First Cladding Layer 4 Active Layer 5 Second Cladding Layer 6 First Current Blocking Layer 6a GaAs Layer 6b GaAlAs Layer 7 Second Current Blocking Layer 10 Current Injection Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruaki Miyake 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A double heterostructure portion comprising a GaAs substrate on which first and second cladding layers sandwich an active layer,
In a surface-emitting type semiconductor laser device having a current blocking layer having a current passage portion on the second cladding layer, the current blocking layer is of the same conductivity type as that of the second cladding layer 2. A surface emitting semiconductor laser device comprising two current blocking layers in order. 2. The active layer is GaAlAs or GaA.
2. The surface emitting semiconductor laser device according to claim 1, wherein the surface emitting semiconductor laser device is s. 3. The first current blocking layer is a GaAs layer and a G layer.
3. The surface emitting semiconductor laser device according to claim 2, wherein the aAlAs layers are laminated in this order.