JPS5856376A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To stabilize a lateral mode, and to obtain high output by forming a guide mechanism effectively using the change of a refractive index by a P<+> type diffusion layer and the change of a refractive index by carriers being injected. CONSTITUTION:An active layer 9, which consists of a GaAlAs semiconductor layer, etc. and generates laser oscillation, and clad layers 8, 10, which have forbidden band width larger than the active layer 9 and hold the active layer 9, are formed onto a substrate 7. The P<+> type diffusion layer 13 is shaped through the diffusion of Zn, etc., and a P<-> pushed-in layer 14 is formed through heat treatment. The P<+> type diffusion layer 13 takes striped form, and the section is W-shaped form. Consequently, impurity concentration is made higher than the center at both ends of a striped region, and the refractive indices becomes smaller than the center. Refractive indices at both ends of the striped region are further lowered through the injection of currents from a P-N junction section 17 under the state of operation. Accordingly, the laser device, the guide mechanism thereof is effective and which has striped type double-hetero structure, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a semiconductor laser device 11 having a stripe structure.
1K, and particularly relates to a semiconductor radar device having a refractive index guide function.

Semiconductor lasers are relatively easy to select wavelengths compared to other laser systems, and have many advantages such as small wrinkles, high efficiency 4-operation, short lifespan, high-speed direct modulation, and single-length operation. It is used as a light source in practical systems of transmission burial volumes.

Figure 1 is a cross-sectional view of a conventional semiconductor laser showing its structure. Conventionally, an n-type rad layer 3.8 is placed between the n-type active layer l from above and below, and zinc (Za)
When trying to attach a refractive index guide by diffusion, %1st
As shown in the figure, there is a high concentration Za diffusion layer up to near the active layer 1, that is, P
After forming the 10-type diffusion layers close to each other, heat treatment is performed to make the active layer l smaller than the impurity concentration of the 10-type diffusion layers.
- A structure in which the shaped indentation layer 5 is provided with conductive material is the easiest to manufacture. However, in this structure, the P ten diffusion number 1-4 in the ninth active layer 1 is close to the active layer l.
A region corresponding to the width of the part where is close to the active layer IK (hereinafter, the % line region will be referred to as the stroke region)
The impurity -K in the region is high, and therefore the refractive index in that region is low. On the other hand, in the operating state, as the injected current R1 increases at the pn crest 6 in the active layer l, a carrier storm in the stripe region 111111 occurs, and the refractive index at both ends of the region center area is low. The cell 77 orcus is such that light is confined in the center. Figure 11 shows 8.
11 shows the refractive index distribution in the active layer of the semiconductor laser device having the structure shown in FIG. As can be seen from the stripe z diagram, it is beneficial to have a low refractive index at both ends of the stripe region in order to inject minority carriers.

It is said that the decrease in the refractive index within the stripe region caused by the proximity of the P 10-shaped diffusion layer 4 to the active layer IKM makes it impossible to obtain the refractive index difference of filW, making it impossible to achieve an effective guiding function. There are drawbacks.

The object of the present invention is to provide a semiconductor laser that can stabilize the transverse mode and achieve high output by using a guide mechanism that uses the refractive 4 change due to the %P dec-shaped diffusion layer and the refractive index change t-M effect due to the injected carriers. The O stripe 1 in
Contained impurities in a cross section perpendicular to the direction of the impurity region of a striped double heterostructure having a region
The shape of fIliI is characterized by being away from the active layer near the center and approaching the active layer on one side.

The present invention will be explained below using a manufacturing method and a semiconductor laser device 11 according to an embodiment of the present invention.

Gas is a cross-sectional view of the device showing the manufacturing method and semiconductor laser ifcmt according to one embodiment of the present invention. n-type GaAs
On the substrate, the thickness is 15μm and the impurity concentration is 5xl□c
n-type Ga (1,6Atg, Am layer (Crabt layer) 8, thickness Q, tIIm and impurity WaX 1lxlo
“1-1 n-type” 06Ql”@, @BAm layer (active 4
> us thickness (Fig. 8 1aj). Next, the cladding layer IQ
Similarly, 6 to 81 stripes ms are formed, and in the region other than -8 and the center of S, a 2 μm 1lli mask double*g, here silicon nitride 8i, N, and Jig-th Ilz are formed. The impurity mW101 (IO
After forming the ``m-'''P 10-shaped diffusion layer 1B in the 2-rad layer lo, the old INI film is removed and the impurity is once IQ''L-IQ''1m-'' by heat dissipation with s9GQr:. At this time, the shape of the P-type diffusion layer 18 in the cladding layer IQ is smaller than the active layer 9 @fLs at the center of the stripe width, and the active J@9 at the edge of the width.
Take the W shape ft approaching (#!Easy diagram (b))
.

:&j? , 84. N, 11 to 11 will be esdg after this
used as. Finally, on 81sNJ11 and cladding layer 1G, gold zinc (AaZn) electrode #A15, substrate T11
A gold germanium (AuGe) electrode +IA16 is provided on the il (FIG. 8, 1cn).

In the present invention, since the P type expansion layer 1g has a W shape,
At two locations close to the active layer, that is, at both ends of the stripe region, the concentration of axes is higher than at the center of the wrinkled region, and therefore the refractive index is lower than at the center. On the other hand, in the active layer, p-o1 in active 1@9! By injecting a current from the joining part 17, o-1 of the p-n board base part 17
That is, as the number of carrier plates increases at one end of the stripe region, the refractive index at that portion decreases, and in addition to the above-mentioned factors, the refractive index at both ends of the stripe region decreases to the same degree. The figure shows the refractive index distribution and light emission pattern in the active layer of one embodiment of the present invention.According to the present invention, since the refractive index can be increased, the guide mechanism works effectively, and the transverse mode It is also possible to obtain a stable V-the-t-. Self-focus increases as the amount of current increases! The current-light output characteristic has the advantage that a high light output range can be obtained.

In addition, using the semiconductor radar device of the present invention, the change in output with respect to the change in current, that is, the change in electric current/change in electric power, was measured and the result was 0.5 W/person.

Furthermore, @sparseness was obtained with lsOmW[. Conventional semiconductor lasers usually have 0. It is thought that the efficiency was improved by making the P-shaped diffusion layer 18, which cannot obtain g-0.8W/AL, into a W shape.

According to the present invention, by effectively using the change in the refractive index due to the four conductive layers and the change in the refractive index due to the layer during injection, it is possible to achieve stable transverse mode and high output power. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the semiconductor laser device showing the structure of a conventional semiconductor laser. FIG. FIG. 4, which is a cross-sectional view of the semiconductor laser device and the manufacturing method of one embodiment, shows the refractive index distribution and light emission pattern in the operating conditions of the semiconductor laser device having the structure shown in diagram @S. 0 1, II...Active layer, $'elle8-10.
... Cladding layer, 4.18 ... P-shaped diffusion layer, 5*Todo ... P-type intrusion layer, 11.12
・・・・・・Insulating film/mask film 17 Mouth bud 2 Diagram J (0) (6) Author 31 5 1Δ (C)

Claims (1)

[Claims] an active layer that causes Raded oscillation, first and third cladding layers that have a larger forbidden band width t- than the active layer and sandwich the active layer, and a resistor that maintains a constant current path in one of the cladding layers. In a semiconductor laser device with a stripe-type double heterostructure having a two-beam-shaped impurity region, the shape of the equal concentration fllI of the contained impurity in the cross section perpendicular to the length direction of the primary stripe-shaped impurity region is approximately A semiconductor laser device characterized in that it is separated from an active layer and close to the active layer on both sides.