JP2564813B2 - A (1) GaInP semiconductor light emitting device - Google Patents

Description

The present invention relates to the structure of an AlGaInP semiconductor laser device.

(Conventional Technology and Its Problems) FIG. 3 shows the structure of a conventional AlGaInP semiconductor laser device and its manufacturing process. The element structure is shown in FIG.
It is equipped with a kind of Ridge type waveguide mechanism to stabilize the transverse mode. This conventional element structure has major problems and difficulties in manufacturing. The manufacturing process is shown in FIG.
It can be roughly divided into three steps, (b) and (c). In the figure, (a) is a step of manufacturing a double heterostructure wafer,
(B) shows a mesa etching process step for making a waveguide mechanism, (c) shows a buried growth or regrowth step for completing the waveguide mechanism, and each figure shows a semiconductor structure formed by these steps. FIG. The above-mentioned manufacturing problem is controllability of the process shown in FIG.
The AlGaInP clad layer 3 is etched into a mesa shape by using the etching mask 30. At this time, the thickness of the AlGaInP clad layer 3 left on the active layer 1 is largely related to the laser characteristics of the device, and this thickness is large. In that case, the higher-order transverse mode oscillates easily, and if the active layer is exposed, the current-voltage characteristic deteriorates, and even laser oscillation does not occur. As described above, although high controllability is required for the remaining film thickness of the cladding layer 3, the control is performed by the etching rate and time of the etching solution, which is very difficult and the yield is poor. Further, this method has a problem such as homogenization within the wafer surface, and is not suitable for processing a large-area wafer.

An object of the present invention is to solve the above problems from the viewpoint of the structure of a semiconductor laser and to provide an AlGaInP semiconductor laser which is easy to manufacture.

(Means for Solving Problems) AlGa provided by the present invention in order to solve the above problems.
InP semiconductor light emitting device is a GaInP or Al on a GaAs semiconductor substrate.
A GaInP active layer has a forbidden band wider than this active layer.
It has a double hetero structure sandwiched by a clad layer made of lGaInP, and a new clad layer made of AlGaInP having a larger forbidden band width than that of the active layer is formed on the double hetero structure via an etching stopper layer made of AlGaAs. The clad layer is sandwiched from the left and right in the stacking plane.AlGaInP or A with a larger forbidden band width than the new clad layer.
The present invention is characterized in that a current block layer made of lInP or a current block layer made of GaInP, AlGaInP, GaAs or AlGaAs having a band gap smaller than or equal to that of the active layer is laminated.

(Operation) FIG. 1 is a schematic sectional view of a typical AlGaInP semiconductor light emitting device according to the present invention, and FIG. 2 is a manufacturing process drawing thereof. Ga
It has a double hetero structure composed of an active layer 1 made of GaInP or AlGaInP and clad layers 2 and 3 on an As substrate 10,
An etching stopper layer 7 made of AlGaAs is stacked on top of this, and a layer for forming a ridge-type waveguide mechanism composed of an AlGaInP clad layer 4 and a current block layer 5 is further stacked thereon. According to the configuration of the present invention, the difficulty of the mesa etching process step in the conventional manufacturing process is eliminated. That is, the AlGaIn of the present invention in FIG.
The manufacturing process of the P light emitting device corresponds to the conventional mesa etching process process shown in FIG. 3B, but the thickness of the clad layer remaining on the active layer 1 at this time is not determined by the remaining film thickness by etching. It is determined by the film thickness of the clad layer 3 laminated in advance, and is always controlled to be constant. This is because the cladding layer above the active layer is the AlGaAs etching stopper layer 7
This is due to the characteristics of the element structure in which the AlGaInP clad layer 4 subjected to mesa etching and the remaining clad layer 3 are separated in advance. This effect can be easily obtained by using a mixed solution of HCl and H ₂ O as an etching solution. AlGaAs is hardly etched by this etching solution, and etching naturally stops above the AlGaAs etching stopper layer 7. If the AlGaAs etching stopper layer has a thickness of about 100Å, the effect can be sufficiently obtained, and the waveguide mechanism is hardly affected.

(Example) Hereinafter, the present invention will be described in detail with reference to Examples. First
FIG. 2 and FIG. 2 are a sectional view and a manufacturing process diagram of an embodiment of an AlGaInP semiconductor light emitting device according to the present invention. First
Figures and 2 show typical Al according to the present invention in the column of (action).
Although the GaInP semiconductor light emitting device and the manufacturing process thereof are shown as the drawings, one embodiment of the present invention and the manufacturing process thereof will be specifically described with reference to these drawings. As shown in FIG. 2 (a), metal-organic vapor phase epitaxy (MOVPE
Method and the following abbreviated method), a Se-doped n-type GaAs buffer layer 20 is deposited, and then Se-doped (Al _0.4 Ga _0.6 ) with a thickness of 1 μm
_0.5 In _0.5 P Clad layer 2, 0.1 μm thick undoped GaInP
Active layer 1, 0.2 μm thick Zn-doped (Al _0.4 Ga _0.6 ) _0.5 In
_0.5 P clad layer 3, 400 Å thickness of Al _0.5 Ga _0.5 As etching stopper layer 7, 0.8 μm thickness of Zn doping (Al _0.4 Ga _0.6 ).
_0.5 In _0.5 P clad layer 4 was sequentially laminated. Next, as shown in FIG. 3B, after forming an etching mask 30 made of SiO ₂ , the AlGaInP clad layer was etched for 1 minute with a mixed solution of HCl and H ₂ O to obtain a mesa shape. At this time, the mirror surface property of the wafer is temporarily lost due to the etching, but when the wafer is etched to the upper part of the etching stopper layer 7, the mirror surface property is restored again and the etching naturally stops at the upper part of the AlGaAs etching stopper layer 7. Even if the etching time, the etching rate of the etching solution, and the thickness of the AlGaInP clad layer 4 are changed to some extent, the obtained mesa shape is almost constant, and the thickness of the etching residual layer on the active layer 1 is the AlGaInP in the step of FIG. This is the laminated thickness of the clad layer 3 and the AlGaAs etching stopper layer 7. Next, as shown in FIG. 2 (c), two more times
Se-doped n-type GaAs current blocking layer 5 grown by MOVPE
Are selectively grown on the left and right sides of the AlGaInP cladding layer 4, and then a Zn-doped p-type GaAs cap layer 6 is laminated on the entire surface to complete the laser device structure. The process of this figure (c) is no different from the conventional one. In this embodiment, the current blocking layer 5
Is GaAs, but it is not necessary to use GaAs as long as the semiconductor has a forbidden band width equal to or smaller than that of the active layer 1 or a semiconductor whose forbidden band width is larger than that of the cladding layer 4. GaInP, AlGaInP,
Either AlInP or AlGaAs may be used. Further, the etching method may be vapor phase etching containing hydrochloric acid gas as a main component.

(Effect of the Invention) The AlGaInP semiconductor light emitting device of the present invention has a structure that is easy to manufacture and is excellent in mass productivity, as described in the sections of (Operation) and (Example).

[Brief description of drawings]

1 is a sectional view of a semiconductor laser which is an embodiment of the present invention, FIG. 2 is a manufacturing process diagram of the semiconductor laser of FIG. 1, and FIG.
The figure is a manufacturing process diagram of a conventional semiconductor laser. 1 ... Active layer, 2,3,4 ... AlGaInP cladding layer, 5 ... Current blocking layer, 6 ... Cap layer, 7 ... Etching stopper layer, 10 ... GaAs substrate, 20 ... Buffer layer, 30
…… Etching mask.

Claims (1)

(57) [Claims] 1. A double hetero structure in which an active layer made of GaInP or AlGaInP is sandwiched by a cladding layer made of AlGaInP having a band gap larger than that of the active layer on a GaAs semiconductor substrate, and AlGaAs is formed on the double hetero structure. The forbidden band width is larger than that of the active layer through the etching stopper layer
A new clad layer made of AlGaInP and a current band layer made of AlGaInP or AlInP having a larger forbidden band width than the new clad layer sandwiching the new clad layer from the left and right in the stacking plane, or a forbidden band more than the active layer GaInP, AlGaInP, GaAs or AlGa with small or equal width
An AlGaInP semiconductor light emitting device, characterized in that a current block layer made of any of As is laminated.