JPS5931084A - Injection type laser - Google Patents

Abstract

PURPOSE:To increase the photo output of limit and decrease the reactive power by a method wherein the structure is so formed that the P-N junction in the neighborhood of a resonant end surface does not reach the hetero junction between an electrode side semiconductor layer and the semiconductor at the center, in a crank type TJS (transverse directional junction stripe) laser. CONSTITUTION:An N type GaAs substrate 1, N type AlyGa1-yAs layer 2, N type AlXGa1-XAs layer 3, and N type AlZGa1-ZAs layer 4 are successively laminated, the required part of each layer is changed into a P type, and accordingly P type regions 12-14 are formed. The P-N junction plane is bent to the P type region side in the neighborhood of the resonant end surfaces 51 and 52, resulting in the formation in crank form. In the crank type TJS laser constituted in this manner, the P type AlZGa1-ZAs region in the neighborhood of the resonant end surface is so constituted as not to reach the hetero junction part between the N type layer 3 and the N type layer 4. By constituting like this, the photo output of limit is increased, and the TJS laser with decreased reactive power can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection laser, and more particularly to a transverse junction stripe rTransverse Junction 5t.
ripe: T JS') This relates to increasing the output power of lasers.

The 'I'J8 laser is an excellent injection laser with a low threshold and stable single mode oscillation.

The problem with this T and TS laser is that the output is about 20'mW.
When this happens, deterioration occurs due to destruction of the resonant end face. In order to increase the output, it is necessary to improve the critical optical output at which end face destruction occurs. In conventional T and TS lasers, the laser light is pn
The carriers are extracted from a carrier injection region approximately 20 μm wide along the junction. In this case, in the carrier injection region exposed to the resonant end face (bl) s (52), the density of injected carriers decreases due to surface recombination, resulting in insufficient population inversion, and heat generation due to absorption for strong laser light. occurs, and the temperature eventually rises until the crystals melt.

As a measure to improve this limit optical output, crank type T
A JS laser has been proposed.

FIG. 1 is a perspective view showing the basic structure of a crank type TJ8 laser. In Figure 1, (1) is an n-type GaAs substrate crystal, (2), (3) and (4) are n-type GaAs substrate crystals.
n-type AZ y G sequentially formed on s-substrate crystal (1)
a 1-y As layer, n-type A7°Ga +, As layer and n-type A1! yzGa, -, As layer (y, y'>x). H, +11 and (14) are each n-type A l
y Ga 1 □As layer (2), n-type Al xG
a + , A 8 layer (3) and n-type Al,.

P-type AI in which necessary parts of the Ga 1-,tAs layer (4) are converted to p-type!

Ga 1-y As region, p-type A Z , Ga 1-
, A, 8 region and p-type Al, rGa, -y, As region. (51) and (52) are the resonant facets extending from the open plane, and (6) is the output laser beam. In FIG. 1 and the subsequent figures, only the exposed surface or cut end surface of the p-type semiconductor is shaded to facilitate interpretation of the figures.

Are the resonant end faces (51) and (52) Aj? .

Ga,,As/AlxGa,-,As heterojunction surface and Al,Ga,-xA,s/Al,,Ga
, -y, is formed by a pair of planes perpendicular to the two junction surfaces with the AS heterojunction surface. The pn junction surface is the resonant end surface (
51) and (52) are bent toward the p-type region and formed into a crank shape.

In the crank type TJ8 laser described above, the pn junction is bent toward the p-type region near the resonant end face (ax), (52), and the laser beam is extracted from the n-shaded region. In this strategy, the strong laser light is not guided to the region where incomplete carrier population inversion occurs due to the different plane recombination of the injection beam, but is emitted through the n-shaded region with little absorption, so the critical optical output can be reduced. This can be improved by about 10 times compared to the conventional method. However, the current flowing through the pn junction near the resonance end face (bl) and (52) is a reactive current that does not contribute to laser emission, and reducing this reactive current is required from the perspective of operating at higher temperatures. I had a hard time with an assignment.

This oscillation F3A was made in view of the above points, and the pn junction is connected near the resonant end face to the semiconductor layer on the side to which the electrode is bonded among the three semiconductor layers forming the two heterojunctions. The critical optical output is large due to the layer formed so as not to reach the heterojunction formed by the semiconductor layer.
The purpose of this invention is to provide a TJS laser with small reactive power.

FIG. 2 is a front view of the main part of an embodiment of the TJ8 laser according to the present invention, viewed from the resonance end face side, and FIG.
FIG. In FIGS. 2 and 3, the same reference numerals as in FIG. 1 represent the same components as shown in FIG.

(14a) is a portion excluding the vicinity of the resonance end face (51) and (5z).

The first p-type AZ y formed to reach the Gap-, As/Al,, Ga1-,, As heterojunction
(Ga 1-y' As region, (14b) is AlxGa 1-, As near the resonance end face (bl) + (52)
/Al, /Ga1-y A second p-type kl, IGa1-, formed so as not to reach the /As heterojunction.
, in the As region.

In the 'I' JS laser of the above embodiment, the resonant end face (51
).

(52) The nearby p-n junction does not intersect with the heterojunction, and the Al
,.

Since it is in the Qa and As layers, the laser beam is n-type Afμm,
,,Yaw-y reactive power can be reduced. This means that the barrier potential of a pn junction in a semiconductor with a wide bandgap can be larger than that of a pn junction in a semiconductor with a narrow bandgap, and when these pn junctions are connected in parallel, the current This is because it is concentrated at the pn junction in the semiconductor, which has a narrow forbidden band width.

Next, the main steps of the method for manufacturing the above embodiment will be described.

The method shown in FIG. 4 uses Zn(
In order to reduce the diffusion depth of zinc) near the resonance end faces (51) and (52), a thin insulating film (7) made of 813M4 or the like is replaced with an n-type Al, J Ga 1-, HAs layer (4).
resonant end face (51).

(52) After forming on the surface of a nearby portion, Zn is diffused to form a pn junction.

The method shown in Fig. 5 is to increase the thickness of the n # Al, Ga1-, As layer (4) near the resonance end face (bl)z (52) and perform Zn diffusion to form a p-n junction. It is.

FIGS. 6 and 7 are cross-sectional views showing other different embodiments of the present invention in which a GaAs layer is formed on the Al y t Ga 1-, Z As layer to improve ohmic contact. Figure 6 shows n-type Al y HGa s.
-y z N-type layer aAs of uniform thickness on As layer (4)
A layer (8) was formed, and a pn junction was formed in the same manner as in Fig. 4, and Fig. 7 shows n-type Al y t Ga1.
-y” 8 layers (4) with thickness resonant end face (5x).

(52) A thick n-type aAs layer (8a) is formed nearby, Zn is diffused, and the resonant end face (51) 1 (52
) In the vicinity, Aly I Ga 1-y / As
A pn junction that does not reach the layer is formed. f18)
, (18a) is a p-type layer aAa layer.

As mentioned above, in the injection laser according to the present invention,
In the vicinity of the resonant end face, the pn junction is formed so as not to reach the heterojunction formed by the third semiconductor layer on the side where the electrode is formed and the second semiconductor layer in the center; Since the vicinity of the resonant end face of the second semiconductor layer on the extended surface of the pn junction in the main part is an n-shaded region, the critical light output can be improved. Furthermore, since the pn junction near the resonant end face does not reach the central semiconductor layer where the forbidden band width is narrow, reactive power can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the mounting part of a crank type TJS racer, FIG. 2 is a front view of the main parts of an embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIGS. 4 and 5 show the T of the embodiment shown in FIGS. 1 and 2, respectively.
, sectional views showing essential steps of different methods for manufacturing a TS laser, and FIGS. 6 and 7 are sectional views showing essential parts of other different embodiments of the present invention. In the figure, (1) is an n-type GaAs substrate crystal, (2) is an n-type Al y aa l □A8 layer, and (3) is an n-type 1'
, Ga1-, A13 layer, (4) is n-type A/! ylGa
1-y, A8 layer, ('l + (8a) is n-type GaAs
JtJ, o'a is p-type A-1y Ga 1-y 8%
area, 1+J a: p-type A t' , Ga 1- voice area, (14a) is the first p-type A ey (Ga s -
y l A s region, (14b) is the second p-type AJ, l
Ga1. , As region, (18) , (lea) is p-type G
aA, s layer, (51) and (52) are resonant end faces. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno (1 other person) Figure 2 12 ------- Figure 4/,/ Figure 5

Claims (2)

[Claims] (1) A first semiconductor layer, a second semiconductor layer, and a third semiconductor layer are sequentially stacked, and the forbidden band width of the second semiconductor layer is the same as that of the first semiconductor layer and the third semiconductor layer sandwiching the second semiconductor layer. The above three semiconductor layers are divided into a p shadow region and an n shadow region by a pn junction plane that intersects with the two heterojunction planes that they form. p
In the device having a resonant end surface that is a parallel plane almost perpendicular to the n-junction surface, and in which a p-side electrode and an n-side electrode are formed on the third semiconductor layer side, the p-n junction An injection type laser, characterized in that it is formed so as not to reach the heterojunction formed by the second semiconductor layer and the third semiconductor layer. (2) The injection type according to claim 1, characterized in that a semiconductor layer is provided between the third semiconductor layer and the p-side electrode and the n-side electrode to improve ohmic contact between these electrodes. laser.