JPS58162088A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To obtain a semiconductor laser which can be simply controlled for the thickness of a grown layer by forming a side groove which extends in parallel with the groove at both side of the groove and has the same depth as the groove and a width larger than that of the groove. CONSTITUTION:The first clad layer 3 made of P type Ga9.5Al9.5As is grown at growth start temperature of 780 deg.C and at gradually cooling speed of 0.5 deg.C/min on a substrate 1 formed with a groove 2 and side grooves 10 in such a manner that the thickness of the layer at the flat part is approx. 0.1mum and a recess is formed and bent on the surface on the groove 2. Since growing component is dispersed and concentrated in each groove, the growing speed at the groove is decelerated. Then, when an active layer 4 made of Ga0.7Al0.3As is epitaxially grown continued to the layer 3, the thickness of the layer on the groove 2 becomes 0.1mum in approx. 30 sec. This is because the surface of the layer 3 is bent in recess shape on each groove so that growing component is dispersed and concentrated at the bent part with the result that the growing speed is decelerated on the groove 2. With this structure, the growing speeds of the layers 3, 4 are delayed as compared with the conventional one, thereby simplifying the control of the thickness of the layer.

Description

[Detailed description of the invention] (nner) type semiconductor ray fK.

Figure 1 shows this conventional elm-ft, and (1) is an n-type Ga
A semiconductor substrate made of As is formed, and a groove (2) extending perpendicular to the plane of the paper is formed on the entire surface of the substrate. (3
) is the n-type Ga deposited on the main surface of J[(1)
<-xA/xAs (0<x<1) In the first cladding layer, the upper surface of the groove (2) of the first cladding layer is curved in a concave shape. (4J is the first layer mentioned above (
3) GB hym/yA (1<(g≦Y
<1. The active layer 1 is formed such that Y<X), and the active layer 1 is formed so that the layer is thickest at the curved and cut-off portion above the groove (2). (5) is above the active layer (4)
A second cladding layer made of C@Fa P3Ga+-xAs2>b, (6) is a cap layer made of n-type GaAs laminated on the second cladding layer, and the cap layer is This is the ninth one that makes ohmic contact with the electrode being formed. C7) is a diffusion S slope formed by diffusing Zn (zinc) from the surface of the cap layer (5) to a depth extending from the second cladding layer (5JK) along the groove (2).
181 (97 is the surface of the diffusion area 171 and group #1, respectively)
(1) Automatic electrical conductivity with VC formed on the back side @1. The second electrical box, afjlls, is formed by a liquid phase epitaxy method.

When a current is applied by using the first electrode (8) as the positive electrode and the second electrode 197 as the negative electrode in the running race f, the current flows directly above the groove (2), and the current flows directly above the groove (2). Luminescent recombination occurs within layer (4). In addition, since the active layer 1 (4j) directly above the groove (2) is thicker and curved than the other parts, the active layer 11143, which is essentially rejected, has a low optical refractive index and a large forbidden band width. 2nd Clad '1l13J
(5) Surrounded by rC from all sides.

Therefore, the recombined light and current generated in the active layer (4j) are well confined within the active layer (4) above this groove (2), resulting in a single-transverse mode laser beam with a low threshold current. The applied current spreads into the active layer (4) other than the upper part of fi (2), but the recombination light generated in the active layer (14) other than the upper part of the groove is rejected. In the figure, the layer thickness of the first cladding layer (3) directly below the layer is very thin (usually α
(one voice or less) passes through the first cladding layer and is absorbed by the substrate with a small band gap.

However, in the case of Ray f, there was a problem that the kosode length at the time of manufacture was low.

The cause of the interstitial layer is the growth components in the growth layer, such as the layer for GaAs members, during liquid phase growth.
This is because the (arsenic) component is concentrated in the grooves and is almost absent in the flat areas, and the growth rate of the single crystal is 5 to 10 times faster in the grooves than in the flat areas.

For example, the above-mentioned groove (2J) has a width of 5 mm and a width of 5 mm, and the first cladding layer (3) is P-type Gao, sAl.
, IAI and j! New first cladding layer [3 grooves 1
21 k & When bending and setting the layer thickness of the first cladding layer (3) other than the upper part of the groove to about α1 Iw, the growth start temperature is 780°C and the slow cooling is 1° α5°C/min, then the first cladding layer (3) will reach the first cladding layer in about 50 seconds. 1 cladding layer (3) is formed.

As the growth rate is fast, it is difficult to control the layer thickness of 11 cladding units with the current growth equipment, and therefore the first cladding layer (37w#r) cannot be formed into the desired shape, and the above-mentioned period of time cannot be formed. occurs.

For example, the thickness of the active layer (4) must be kept to a maximum thickness of 1μ to facilitate laser light oscillation.
4) When growing G * o, y A / a, sAB 1 Jj, on the flat first cladding layer (3), if the growth is continued from the first cladding layer (3j), about 15
1 of I11 tone thickness is a member in seconds. In addition, the growth rate of the active @ (4) on the curved first cladding layer (3) must be the same as that of the flat part, and it is difficult to control such a short period of time, so the growth rate of υ decreases. The present invention was developed in consideration of the above-mentioned MKm, and is intended to provide a semiconductor layer ψ having a structure in which the thickness of the grown layer can be easily controlled.

As mentioned above, in liquid phase growth, the growth rate in the groove is extremely fast, 5 to 10 times the growth rate in the flat area, but when grooves with the same number of lines are provided on the opposite substrate, the growth rate of the growth component increases. Since the concentration is distributed over six grooves, the growth rate in each groove is faster than when there is only one groove.

The present invention has been made by skillfully utilizing the existing ridges, and the present invention will be explained below with reference to Examples.

FIG. 2 shows a semiconductor laser according to an embodiment of the present invention.
#i1 Fig. 1 and Oka - part have the same number, because it extends parallel to the prayer groove, has the same depth as the new groove, and has a larger width. is attached.

For example, +1, upper e groove [2J and va*aaant
The formation of the grooves, which have a pitch of 15 tones and a width of 5 tones and 10 tones, was created using Ichichi &0neka's lithographic techniques.

On the substrate (1) on which the groove +23 and the 91741111 hammer are formed, the thickness at the flat part is about 11 tones Iw.
pHGam, sA was grown at a growth starting temperature of 780°C and a slow cooling rate of a5°C/min so that the surface curved concavely at the grooves (2).
When the first cladding layer (conducted with three-layer growth) consisting of As, the member ICR molecule @Kasutomo is formed, as mentioned above, if there is a groove in the groove, each groove rc grows. Because the components are dispersed and concentrated, the success rate with six grooves is slower than in the conventional case with one groove.

Further, at this time, the surface of the first cladding (3) formed on the side groove IMiIIa is also curved in a concave shape.

Next, as in the conventional case, gas, 7A10. The layer thickness at the top of the groove (27) was about VC50 seconds, which is about α1 SW.This is because the first cladding layer (3J surface is This is because the U22 component is dispersed and concentrated in the concave curved part at the top of the groove, slowing down the growth rate on the groove (2).As described above, the semiconductor laser of this example In this case, the growth rate of the first cladding 1l (3) and the active layer (4) is slower than that of the conventional method, and therefore, layer control becomes easier.

In the gutter IMinG, the first cladding layer (3) has a desired shape Kb5C on the groove (groove 12, assuming that it is smaller in depth and width than 21). No curvature is formed on the surface. If no curvature is formed in this way, the activation of the upper part of the groove (2) is similar to the radar in Fig. 1.
The growth rate of (4) is reached, and layer thickness control becomes difficult.

Similarly, when the depth of the side groove becomes small, no curve is formed, and the width of the concave groove (2
), and the depth is equal to or larger than the groove (2J to Sanshi-dai), and when the first cladding pigeon (3) has formed the desired shape on 23 KFfr, the first cladding pigeon (3) is formed in other parts of the surface of the 4Jlil plate 10. The cladding layer (3) may not be a member.

Therefore, it is preferable that the size of the above groove (1) is as deep as the groove (2) and that the width is equal to or larger than the groove (2). 1 cladding layer (3+k
I can do liE costumes.

Also, in the laser shown in FIG.
In order to prevent laser oscillation from occurring in the active layer (4) formed on the groove opening 111 when applying the forward direction II flow, the groove (2) and - It is preferable that the interval between the groove and the groove is 20 tones tm-sopwam,
In this way, part of the applied current will be directed to the upper part of the gutter.
.

Even if it spreads, it is important not to oscillate in order to refuse.
11 The device of this embodiment has a 25 voice disease.The one-value current that oscillates for the ray ψ of Fig. 1 and the KsP of this embodiment. When looking at the yield of a grown layer with a grain size of 50 M1 or less, the radar in Figure 1 achieved a yield of 40 bites, while the radar of this embodiment achieved a yield of 8.
It became about 0 road.

In this embodiment, the semiconductor material -f, which is a Gap/As-based material, will be described. However, the present invention is not limited to this, and the present invention can be applied to a semiconductor laser FRC using other semiconductor materials.

As is clear from the above description, in the semiconductor radar of the present invention, since the layer thicknesses of the first cladding layer and the active layer can be easily controlled, the semiconductor radar can be manufactured with a yield of 1.

[Brief explanation of the drawing]

Figure 2 is a cross section showing an embodiment of the present invention, ff14. (υ... Semiconductor J & board, (2) - groove, (3)...
First cladding layer, +4J-... active layer, +5J... second cladding layer, -... side groove. 3

Claims (1)

[Claims] (1) - A groove is formed approximately in the center of the soil surface, - A semiconductor substrate exhibiting a conductivity type, a first cladding layer laminated on the one board and exhibiting a conductivity type between the pray & plate, and a top of the gs1 cladding layer; The first cladding layer laminated on top of the first cladding layer has a high optical refractive index and a small forbidden band width, and the active layer laminated on top of the active layer has a low optical refractive index and a large forbidden band width. and a second cladding layer having a conductivity type opposite to that of the first cladding layer, which extends substantially parallel to the groove on the whole surface of the substrate and has the same depth as the groove. A semiconductor laser characterized in that a side groove is formed which is large and has equal or large width.