JPH0442981A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To form the shape of a current narrowing region of a substrate with high reproducibility by inverting a reverse conductivity type first type semiconductor layer to a first conductivity type in a stripelike region of depth reaching a first conductivity type first type semiconductor substrate through the layer, and forming in a mesa stripe structure in which the stripelike region is formed in a protruding stripe. CONSTITUTION:An n<+> type GaAs layer 2 is grown on a p<+> type GaAs substrate 1 of a crystalline surface (100). An SiO2 mask 10 having a stripe window is formed on the layer 2 in a direction <011>, Zn is diffused through the window of the mask to form a p-type diffused region 3. After the mask 10 is removed, it is etched through an SiO2 mask 11 formed to hold the region 3, and double stripe grooves 12, 12 are formed. After the mask 11 is removed, a p-type (Al0.7 Ga0.3)0.5In0.5P layer 4, a Ga0.5In0.5P layer 5, an n-type (Al0.7Ga0.3)0.5In0.5P layer 6, an n-type GaAs layer 7 are grown thereon.

Description

[Detailed Description of the Invention] [Summary] A semiconductor light emitting device, particularly a 0. Regarding a 6 μm band visible light semiconductor laser device and its manufacturing method, the shape of the active layer can be formed with good reproducibility to achieve low power consumption, low threshold value, high efficiency,
For the purpose of obtaining a semiconductor light emitting device with low astigmatism, a first type semiconductor layer of an opposite conductivity type is formed on a first type semiconductor substrate of a first conductivity type, and the first type semiconductor layer of the opposite conductivity type is formed on a first type semiconductor substrate of a first conductivity type. The layer is
The conductivity type is inverted to the first conductivity type in a striped region having a depth that penetrates through the core layer and reaches the first type semiconductor substrate of the first conductivity type, and is formed into a mesa stripe structure with the striped region serving as a ridge. On top of the structure having the shape, at least a second type semiconductor layer of the first conductivity type, a third type semiconductor layer having a bandgap smaller than the second type semiconductor layer, and a third type semiconductor layer having a band gap smaller than the third type semiconductor layer are formed. The structure is such that fourth type semiconductor layers of opposite conductivity type having a large band width are stacked.

In addition, as a manufacturing method, a first type semiconductor layer of an opposite conductivity type is grown on a first type semiconductor substrate of a first conductivity type, and a core layer of the first type semiconductor layer of the opposite conductivity type is grown. A striped region with a depth reaching the first type semiconductor substrate of the first conductivity type is
The conductivity type is inverted and the striped region is formed into a mesa stripe structure with protrusions, and thereon, at least a second type semiconductor layer of the first conductivity type, which has a bandgap width smaller than that of the second type semiconductor. It is constructed by sequentially growing and stacking a third type semiconductor layer and a fourth type semiconductor layer of an opposite conductivity type having a larger forbidden band width than the third type semiconductor layer.

[Industrial application field]

The present invention relates to a semiconductor light emitting device, particularly to a 0.6 μm band visible light semiconductor laser device and a method for manufacturing the same.

[Conventional technology]

Semiconductor light emitting devices, especially short wavelength visible light semiconductor laser devices in the 0.6 μm band, have a writing density proportional to the reciprocal of the square of the wavelength, so it is important to improve the performance of optical information processing devices such as optical disk devices and laser printers. It is expected that this device will become a reality.

Semiconductor laser devices for these applications need to have low threshold current and high efficiency to reduce power consumption, and have low astigmatism characteristics to improve writing and reading characteristics. It is necessary.

In order to meet this demand, various visible light semiconductor laser devices have been proposed.

FIG. 3 is a sectional view of a conventional visible light semiconductor laser device.

In this visible light semiconductor laser device, n-GaAs
On the substrate 31, n-A/! GaInP layer 32, Ga
InP active layer 33, p-Aj! A GaInP layer 34 is formed, this p-AfGaInP layer 34 is etched leaving a ridge portion, and an n-GaAs layer 35 is grown thereon with the top surface of the ridge portion covered with a mask. After the removal, a p-GaAs layer 36 is further grown thereon.

According to this structure, outside the ridge part, Ga In
Since the GaAs absorption layer 35 is located close to the P active layer 33, there is a difference in refractive index between the ridge portion and the outside, which makes it possible to confine light in the lateral direction.

However, since this refractive index difference is as small as ~10-3, there are problems such as a high threshold current (and large astigmatism).

Further, in the process of manufacturing this device, three crystal growths are required, which poses a problem in terms of yield.

Therefore, as a structure that increases the difference in refractive index in the lateral direction, the MOVPE growth method (MOVPE growth method) in which crystal growth is carried out by following the shape of the substrate (
A structure has been proposed in which a step is provided in the active layer by taking advantage of the characteristics of metal organic vapor phase epitaxy (organic metal vapor phase epitaxy), and the light emitting region is limited to the tip of the step.

FIG. 4 is a cross-sectional view of a conventional semiconductor laser device in which a step is provided in an active layer manufactured by the MOV PE growth method.

In the device shown in FIG.
1, an n-GaAs layer 42 as a current blocking layer is grown, a region of the n-GaAs layer 42 corresponding to the light emitting region is etched into a groove shape, and a p-AffiGaIn layer is formed on the n-GaAs layer 42.
P layer 43, GaInP active layer 44, n-Al! GaI
It has a structure in which an nP layer 45 and an n-GaAs layer 46 are grown.

The purpose of this device is to provide an inverted trapezoidal step in the active layer and to increase the lateral refractive index difference in the limit j- with the light emitting region located at the protruding portion a of the step.

In this apparatus, when etching the n-GaAs layer 42, the reproducibility is good because the shape of the slope of the groove can be etched with the facet exposed, but the bottom part of the groove can be etched with good reproducibility. Because there are no specific facets, chemical etching cannot be used to create a flat surface.
Therefore, on top of that, P-Aj! There was a problem in that the light emitting region a of the active layer 44 grown through the GaInP layer 43 could not be made flat.

In order to eliminate this problem, the area of the substrate other than the light emitting area is etched, and the MOVPE is etched on the flat surface of the substrate.
A method applying the growth method was proposed.

FIG. 5 is a cross-sectional view of a conventional semiconductor laser device in which a step is formed in an active layer by MOVPE growth using a flat surface of a substrate.

In this device, a region corresponding to the light emitting region on the upper surface of a p-GaAs substrate 51 is etched to form a protrusion that becomes a current constriction portion, and an n-GaAs layer 52 and a P-Af layer are formed on the protrusion.
fiGa InP layer 53, Ca1nP active layer 54, n-
AfGaInP layer 55 and n-GaAs layer 56 are MOVP
It has a structure grown by the E growth method.

In this apparatus, since the surface of the protrusion of the flat substrate can be used, the surface of the semiconductor layer that is subsequently grown can be made even more flat.

[Problem to be solved by the invention]

However, according to the prior art shown in FIG.
As mentioned above, since a flat substrate surface is used, the light-emitting region can be made flatter, but the shape of the slope does not have a specific facet, so chemical etching is used to process it with good reproducibility. n-GaAs layer 52 and p-Aj2Ga InP layer 53
Since this method attempts to adjust the shape of the active layer using the growth shape of , there are still problems in the reproducibility and controllability of the shape of the active layer.

The present invention aims to solve this problem.

[Means to solve the problem]

In the semiconductor light emitting device according to the present invention, a first type semiconductor layer of an opposite conductivity type is formed on a first type semiconductor substrate of a first conductivity type, and the first type semiconductor layer of the opposite conductivity type is a core layer. The conductivity type is inverted to the first conductivity type in a striped region having a depth that penetrates through and reaches the first type semiconductor substrate of the first conductivity type, and is formed in a mesa stripe structure having the striped M region as a ridge. and on top of the structure having the shape, at least a second type semiconductor layer of the first conductivity type, a third type semiconductor layer having a band gap smaller than the second type semiconductor layer, and a band gap smaller than the third type semiconductor layer. A configuration in which type 4 semiconductor layers of opposite conductivity type with large widths are stacked is adopted.

Further, in this semiconductor light emitting device, the first conductivity type is p type, the first type semiconductor is GaAs, and the second type semiconductor is (AI
! xGa+-X) 0.51 no, sP (0<x≦
1), the third type semiconductor, (A I! yG a I-y
) o, sIn o, sP (0≦y<x), 4th
The seed semiconductor is (AlsGa+-s)o. sI
no, sP Cx<z≦1).

In the method for manufacturing a semiconductor light emitting device according to the present invention,
A first type semiconductor layer of an opposite conductivity type is grown on a first type semiconductor substrate of a first conductivity type, and a first type semiconductor layer of a first conductivity type is grown through the core layer of the first type semiconductor layer of the opposite conductivity type. A striped region with a depth that reaches the semiconductor substrate is inverted to the first conductivity type, and the striped region is formed into a mesa stripe structure with protrusions;
Thereon, at least a second type semiconductor layer of the first conductivity type,
a third type semiconductor layer having a smaller forbidden band width than the second type semiconductor;
The fourth type semiconductor layer is of the opposite conductivity type and has a larger forbidden band width than the third type semiconductor layer.
A process of sequentially growing and stacking seed semiconductor layers was adopted.

(Function) In the present invention, a first type semiconductor layer of a reverse conductivity type is formed on a flat first type semiconductor substrate of a first conductivity type, and the first type semiconductor layer of a reverse conductivity type is a core layer. By forming a patented stripe structure characterized by being inverted to the first conductivity type in a stripe-like region with a depth that penetrates through and reaches the first type semiconductor substrate of the first conductivity type, and the stripe-like region is characterized by Since it is possible to use a flat top surface of the substrate and a slope shape that is chemically etched with the facet surface exposed, the shape of the current constriction region of the substrate can be formed with good reproducibility, and therefore, the shape of the light emitting layer with steps that is laminated on top of the substrate can be formed with high reproducibility. A region can be formed with good reproducibility.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

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

In this figure, 1 is p-Ga on the crystal plane (100')
As substrate, 2 is n''-GaAs layer, 3 is striped p-type region with Zn diffused, 4 is P-Aj2GalnP layer,
5 is a GaInP layer, 6 is an n-AfGaInP layer, 7 is an n
-GaAs layer, 8 is Au-Zn/Au
The electrode 9 is an Au-Ge electrode.

In this example, the n''-GaAs layer 2 is grown by MOVPE on a flat substrate surface and on the slopes of striped grooves that can be etched with good reproducibility to expose the facets. Therefore, its shape can be formed with good reproducibility, and furthermore, the shape of the active layer grown thereon by the MOVPE method can be formed with good reproducibility.

As for the laser characteristics of this device, the threshold value is 3Q m
A, efficiency is 0. 30mW/mA-f ace
At t, an output of 30 mW or more was obtained.

Furthermore, while astigmatism was approximately 8 μm in the conventional technology, it was reduced to 5 μm or less in the present invention.

Next, an example of a process for manufacturing the semiconductor laser device according to the embodiment of the present invention will be described.

FIGS. 2(a) to 2(e) are manufacturing process diagrams of a semiconductor laser device according to an embodiment of the present invention.

The process will be explained according to this process diagram.

First step (Fig. 2(a)) MO
n” Ga by VPE method (metal-organic vapor phase epitaxy)
An As layer 2 is grown.

The growth temperature is 700° C., TEG (triethyl gallium) and ASH3 (arsine) are used as source gases, and the molar ratio in the gas phase, V1m ratio, is 40. 5iHa (monosilane) was used as a dopant.

The growth rate is 1 μm/h, and the layer thickness is 1 μm.

Second step (FIG. 2(b)) (011
A SiO□ mask 10 having a stripe window with a width of 4 μm is formed in the > direction, and Zn is diffused through the window of this mask in a closed tube while maintaining the temperature at 700° C. to form a p-type diffusion region 3.

Third step (FIG. 2(C)) After removing the Sin and mask 10 formed in the second step,
A diameter of 4 μm is placed across the striped Zn diffusion region 3.
Sin! with a striped window. A mask 11 is formed.

Fourth step (Fig. 2(d)) Sin with two stripe windows formed in the third step
, through the mask 11, using a mixture of H, SO, and H20□ to form double stripe grooves 12.
form 12.

Fifth step (FIG. 2(e)) After removing the 5in2 mask 1 used to form the double stripe grooves 12.12 in the fourth step, using the MOVPE method, P(Afo, 7Gao, :+
) o, s, I no, sP layer 4 (thickness 1, Op m,
Ga o, s I no, sP layer 5 (thickness 0°07μ
m), n (Afo, tGao, z)o, 5Ino,
An sp layer 6 (thickness: 1.0 μm) and an n-GaAs layer 7 (thickness: 0.5 μm) are successively grown.

The growth rate was 1 μm/h.

In addition, in this example, the growth temperature was 700°C, and the raw material gases were TMA (remethylaluminum), TE
G (triethylgallium), TMI ()trimethylindium), PH3 (phosphin), As H:+ (arsine) are used, and the dopant gas is 5 for n-type.
iH4 (monosilane) and DMZ (dimethylzinc) were used for p-type.

6th step (Fig. 1) After that, A u -Z n / A u is vapor-deposited on the P- substrate side to form the electrode 8, and A 11- G is deposited on the n- growth layer side.
E is vapor-deposited to form an electrode, and the resonator is separated at a cavity length of 300 μm to complete the process.

In the above embodiments, the composition of each growth layer is described as being specific, but the composition is not limited to that, and (AfGaI-x) can be used as the second type semiconductor. . .

I no, s P (0<x≦1) 1 as the third type semiconductor, (A 12 yG a I-s,). ,.

Inci. , P(0≦y<x) As the fourth type semiconductor, (A 12 HG a 1-s)
o, 5Inn. , P (x<z≦1) can be used.

Note that the values of x, y, and z are within a range that can be adjusted around the emission wavelength of 0.6 μm, and the value of 0.5 takes into consideration the matching of the crystal lattice.

〔Effect of the invention〕

According to the present invention, the grown n” GaAs on a substrate
Since the shape of the N 2 current narrowing region can be formed with good reproducibility, the active layer with steps grown on it can be formed with good controllability, making it possible to create a laser device with low threshold current, high output, and low astigmatism. can be obtained with good reproducibility.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention;
FIGS. 2(a) to 2(e) show the semiconductor 1 node of the embodiment of the present invention.
3, 4, and 5 are cross-sectional views of a conventional visible light semiconductor laser device. 1-p ”-〇 a As substrate 2-n ”-Ga As layer 3--Striped P-type region 4-p in which Zn is diffused
-Aj2Ga InP layer 5---GaXnP layer 6-n-A I), GaInP layer'L--n
-GaAs layer 8--Au-Zn/Au electrode 9-Au-G
e electrode (e) Cross-sectional diagram of a semiconductor laser device according to an embodiment of the present invention FIG. 1 (a) (d) (b) Manufacturing process diagram of a semiconductor laser device according to an embodiment of the present invention FIG.
Figure (Part 1) Figure 2 (Part 2)

Claims (3)

[Claims] (1) A first type semiconductor layer of a reverse conductivity type is formed on a first type semiconductor substrate of a first conductivity type, and the first type semiconductor layer of a reverse conductivity type penetrates through the layer. The conductivity type is inverted to the first conductivity type in a striped region having a depth that reaches the first type semiconductor substrate, and is formed in a mesa stripe structure with the striped region serving as a protrusion, and a structure having the shape a second type semiconductor layer having at least a first conductivity type, a third type semiconductor layer having a band gap smaller than the second type semiconductor layer, and a third type semiconductor layer having a band gap larger than the third type semiconductor layer; A semiconductor light emitting device characterized in that a fourth type semiconductor layer is laminated. (2) In the semiconductor light emitting device according to claim 1, the first conductivity type is p type, the first type semiconductor is GaAs, and the second type semiconductor is (Al_xGa_1_-_x)_0_. ＿５、In＿
0__. _5P (0<x≦1), type 3 semiconductor, (Al
_yGa_1_−_y)_0_. _5In_0_. ＿５
P (0≦y<x), the fourth type semiconductor, (Al_zGa_
1_-_z)_0_. _5In_0_. ＿5P(x<z
≦1) A semiconductor light emitting device. (3) A first type semiconductor layer of the opposite conductivity type is grown on the first type semiconductor substrate of the first conductivity type, and a first type semiconductor layer of the first conductivity type is formed by penetrating the layer of the first type semiconductor layer of the opposite conductivity type. A striped region with a depth that reaches the first type semiconductor substrate is inverted to the first conductivity type, and this striped region is formed into a mesa stripe structure with protrusions, and at least a layer of the first conductivity type is formed thereon. A second type semiconductor layer, a third type semiconductor layer with a smaller forbidden band width than the second type semiconductor layer, and a fourth type semiconductor layer of the opposite conductivity type with a larger forbidden band width than the third type semiconductor layer are grown and stacked in sequence. 1. A method for manufacturing a semiconductor light emitting device, comprising the step of: