JPH02143483A - Semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To restrain a reduction in the luminous efficiency even under a high temperature, to maintain high output and to obtain a stable light emission by a method wherein a barrier against an electron transfer is provided by a high-concentration buried layer to lessen the transport factor of electrons and the injection rate of the electrons is made small by a high-concentration buried layer. CONSTITUTION:A high-concentration first conductivity type third buried layer 7 is provided between a second conductivity type second buried layer 6 and a first conductivity type fourth buried layer 8. That is, the side of the buried layers is formed into a pnp<+>pn thyristor structure. For this reason, when a P electrode 11 and an N electrode 12 are biased forward for a laser oscillation operation, electrons are injected from a third clad layer 9 in the layer 8, but part of the injected electrons is stopped from transferring to the layer 6 by a barrier against the electrons which is formed by the following layer 7. As a result, the turn-ON of a parasitic thyristor is suppressed and a leakage current due to the turn-ON of the thyristor can be significantly reduced.

Description

[Detailed Description of the Invention] [Summary] Regarding a buried semiconductor light emitting device, more specifically, a buried semiconductor in which a plurality of buried layers having a silice structure are formed on the sides of a mesa-shaped convex part. Regarding the light emitting device, an object of the present invention is to provide an embedded semiconductor light emitting device that can maintain high output even under high temperatures by reducing leakage current flowing through the plurality of embedded layers. A plurality of buried layers are provided on the sides of a mesa-shaped convex portion in which a first cladding layer of a first conductivity type, an active layer, and a second cladding layer of a second conductivity type are formed on a mold substrate. In the buried semiconductor light emitting device formed by forming a buried semiconductor light emitting device, the plurality of buried layers include a first buried layer of a first conductivity type formed to cover a side portion of the convex portion, and a first buried layer of a first conductivity type formed to cover a side portion of the convex portion; a second buried layer of a second conductivity type formed on the buried layer; and a highly concentrated buried layer formed to cover the second buried layer and whose end portion is in contact with the second buried layer. a third buried layer of the first R electric type; and a fourth buried layer of the first conductivity type.

[Industrial application field]

The present invention relates to an embedded semiconductor light emitting device, and more specifically, to an embedded semiconductor light emitting device in which a plurality of embedded layers having a thyristor structure are formed on the sides of a mesa-shaped convex portion. .

In a buried type semiconductor light emitting device, a thyristor made up of a plurality of buried layers is formed on the side of a mesa-shaped convex portion of an active region, so that the leakage ti current flowing through the buried layers is small.

However, as the use of semiconductor devices expands, there is a demand for semiconductor light emitting devices that can maintain high output even at high temperatures.

[Conventional technology]

FIG. 5 is a cross-sectional view of a conventional buried laser diode.

In the figure, 15 is a first cladding layer made of p-type rnP formed on a p-type 1nP substrate 14, 16 is an active layer made of 1nGaAsP formed on the first cladding IIWIS, and 17 is an active layer made of p-type rnP formed on a p-type 1nP substrate 14. This is a second cladding layer made of n-type 1nP, which forms a mesa-shaped convex active region.

Further, 18 is a p-type 1n covering the side of the active region of the convex portion.
A first buried layer made of P, 19 a second buried layer made of n-type 1nP formed on the first buried layer 18, and 20 a second buried layer made of p-type 1nP formed on the second buried layer 19. 21 is a third cladding layer that covers the entire second cladding [19] and third buried layer 21, and these make pn
A pn-structured cyrisk is formed.

Furthermore, 22 is a cap layer made of n-type 1nGaAsP, 23 is a P electrode, and 24 is an N electrode.

20 In the buried laser diode, the third buried layer 2
0 and the first buried layer 18 have low concentration and high resistance.

This means that when a forward bias is applied between the P electrode 23 and the N electrode 24 in order to operate the laser oscillation, the p-type cylinder 1 is buried in Ji18, the A part is, and the p-type third buried in I! 20 and the p-n junction formed by the p-type cylinder 3 buried w320 and the n-type third cladding layer 21 to minimize the leakage current flowing through it.

[Invention tries to solve it! ! 1! [Problem] However, according to the conventional embedded type semiconductor light emitting device, since the third embedded layer 20 has a low concentration, the electron injection efficiency is high.
During laser oscillation, especially in a high temperature environment, the p of the buried layer yj
The npn thyristor turns on and a large leakage current flows.

Therefore, the current required for laser oscillation flowing through the active layer decreases, resulting in a problem that sufficient optical output cannot be obtained as shown in FIG. 3.

Further, if the leakage current increases further, a problem arises in that the laser oscillation itself stops.

The present invention was created in view of the above problems, and provides an embedded semiconductor light emitting device that can maintain high output even under high temperatures by reducing leakage current flowing through multiple embedded layers. The purpose is to provide

[Means for Solving the Problems] The above object is to provide a first cladding layer 2 of a first conductivity type, an active WJ 3, and a second cladding layer 4 of a second conductivity type on a substrate 1 of a first R conductivity type. In a buried semiconductor light emitting device in which a plurality of buried layers are formed on the sides of a mesa-shaped convex portion, the plurality of buried layers are arranged so as to cover the sides of the convex portion. a first buried layer 155 of the first conductivity type formed; a second buried layer 6 of the second conductivity type formed on the first buried layer 5;
The second embedding 11156 is covered, and the end portion is covered with the first embedding M.
a third buried layer 7 of the first conductivity type with a high concentration formed so as to be in contact with the WJ 5; This is achieved by a buried type semiconductor light emitting device constituted by a fourth buried layer 8 of the first conductivity type having a lower concentration than the third buried layer 7 formed.

Due to the barrier against the trapped electrons, migration to the second buried layer 6 is prevented.

As a result, it becomes difficult for the parasitic silicon risk to turn on, and therefore the leakage current due to the parasitic silicon risk being turned on can be significantly reduced.

Note that since the fourth buried layer 8 has a low concentration, leakage current flowing through the fourth buried layer 8 to the first buried layer 5 through the vicinity of the active region can also be reduced at the same time.

[Effect]

According to the present invention, the third buried layer 7 of the first conductive type with a high concentration is provided between the second buried layer 6 of the second conductive type and the fourth buried layer 8 of the first conductive type. There is. That is, the buried layer side is pnp″p
It has a cyrisk structure of n.

Therefore, for laser oscillation operation, P electrode 11 and N? it
When the poles 12 are forward biased, some of the electrons injected from the third cladding layer 9 into the fourth buried layer M8 are formed by the next high concentration third buried layer 6 [Example] Next Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a buried semiconductor laser diode according to an embodiment of the present invention.

In the same figure, 2 is a p-type formed on a p-type 1nP substrate 1.
A first craft layer made of type 1nP, 3 an active layer made of rnGaAsP formed on the first cladding layer 2, and 4 a second cladding layer made of n-type 1nP formed on the active W2B. A mesa-shaped convex active region is formed.

Further, 5 is a first buried layer made of p-type 1nP with an impurity concentration of 4×10"cm-3 formed to cover the sides of the active region of the convex portion, and 6 is a first buried layer on the first buried Ji!15. The formed n-type!nP has an impurity concentration of 2×10” cm
-' second buried layer 7 is formed on the second buried layer 6,
A third buried layer made of 20-type TnP with an impurity concentration of 2×10"cm-' and a thickness of 0.1 μm is formed so as to be in contact with the first buried layer [5] at the end, and 8 is a second buried layer. 7 and in contact with the first buried J! 55 at the end thereof, the impurity concentration is 2×10”cm−′, f! 1. This is a fourth buried layer made of p-type 1nP with a diameter of 0.5 μm.

9 is an impurity concentration l of n-type TnP that covers the entire second cladding layer and fourth buried layer 8 in the active region of the convex portion.
This is the third cladding layer of Xl0"cm-", and these form a silicon risk with a pnp'pn structure.

Furthermore, 10 is a cap layer for contacting an N-type electric bridge made of n''-type InGaAsP, 11 is Phi, and 12 is
is N@, the pole.

According to an embodiment of the present invention, the second buried layer 6 of the second conductivity type and the fourth buried layer Ji! of the first conductivity type! 1B with a high concentration of the first
Third embedded conductivity type rr! i7 is installed. That is,
The buried layer side has a pnp″pn silicon risk structure.

Therefore, P'rr! due to laser oscillation operation. , pole 11 and N? When the flt poles 12 are forward biased, electrons are injected from the third cladding layer 9 to the fourth buried layer 8, but some of the injected electrons are transferred to the next high concentration third buried layer. Due to the barrier against electrons formed by layer 7, migration to second buried layer 6 is prevented.

As a result, it becomes difficult for the parasitic silicon risk to turn on, and therefore the leakage current due to the parasitic silicon risk being turned on can be significantly reduced.

Further, FIG. 2 is a sectional view of a buried semiconductor laser diode according to another embodiment of the present invention.

The structure of the semiconductor laser diode shown in FIG. 2 is different from the structure of the semiconductor laser diode shown in FIG.
-ζThe difference is that a p° type fifth buried 1513 made of high concentration InP with a thickness of 0.1 μm is provided.

For this reason, the fifth buried layer 13 extends from the third cladding layer 9 to the fourth
Since it acts as a barrier against electron injection into the buried layer J8,
For laser oscillation operation, P electrode 11 and Ni1li electrode 1
2 is forward biased, the n-type third cladding layer 9
The amount of electrons injected into the P-type fourth buried layer 8 decreases.

In addition, the 411th buried layer 8 crosses the barrier of the fifth buried layer 13.
At the same time, the electrons injected into the second embedded layer 6
arrival will be further suppressed.

In both of the above two embodiments, the fourth buried layer 8 has a low concentration, so the resistance is high.
The first
Leakage current flowing into the buried layer 5 can also be reduced at the same time.

In this way, leakage current can be significantly reduced, so high output can be maintained even at high temperatures.

FIG. 3 is a diagram showing this, and in FIG.
The horizontal axis represents the total current (-8) flowing between the P electrode and N1, and the vertical axis represents the optical output (1). Further, the parameter is temperature.

As shown in the figure, when the ambient temperature (Ta) is 25°C, both the conventional buried semiconductor laser diode and the embodiment buried semiconductor laser diode have optical output characteristics of 1.
It extends linearly up to 0 mw or more.

However, when Ta is 100° C., the conventional buried semiconductor laser diode has a large leakage current, so it is necessary to increase the total current in order to maintain the optical output of laser oscillation.

On the other hand, in the embedded semiconductor laser diode of the example, the leakage current is suppressed even when Ta is 100"C. In other words, the current is efficiently used for laser oscillation, and the optical output is There is no saturation tendency in the characteristics, and the output is extended to high output.

(Effects of the Invention) As explained above, according to the semiconductor light emitting device of the present invention, firstly, a barrier to the movement of electrons is provided by the highly concentrated third buried layer to reduce the electron arrival rate; Second, the electron injection efficiency is reduced by the highly concentrated fifth buried layer.

This causes the convex part of the active region to ? To turn on the parasitic risk of pnpnti formed on the buried layer side of 1 loss<<
L, it is possible to reduce leakage current caused by turning on the parasitic silicon risk.

Therefore, even under high temperatures, it is possible to suppress a decrease in luminous efficiency, maintain high output, and obtain stable luminescence.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a buried semiconductor laser diode according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a buried semiconductor laser diode according to another embodiment of the present invention, and FIG. A comparative explanatory diagram of optical output characteristics between a buried semiconductor laser diode according to an embodiment of the present invention and a conventional buried semiconductor laser diode. FIG. 4 is a cross-sectional view of a conventional buried semiconductor laser diode. It is. (Explanation of symbols) l, 14...Substrate made of p-type 1nP, 2.15...
・First cladding layer made of p-type 1nP, 3, 16
=Active layer made of InGaAsl', 4.17...n
2nd cladding layer made of type 1nP, 5.18...first buried layer made of p-type 1nP, 6.19-21st made of n-type TnP! I! buried layer, 7... third buried layer made of p0 type 1nP, 8... fourth buried layer made of p type 1nP, 9.21... third cladding layer made of n type 1nP,
10.22 ・Carrier made of n” type 1nGaAsP/
Tube layer, 11.23...P electrode, 12.24...N electrode, 13...5th buried layer made of p' type 1nP, 20...
・P-type [third buried layer made of nP.

Claims (2)

[Claims] (1) On the substrate (1) of the first conductivity type, the first
A buried layer is formed by forming a plurality of buried layers on the sides of a mesa-shaped convex portion formed of a cladding layer (2), an active layer (3), and a second conductivity type second cladding layer (4). In the type semiconductor light emitting device, the plurality of buried layers include a first buried layer (5) of a first conductivity type formed to cover a side portion of the convex portion, and a first buried layer (5) of a first conductivity type. 5) of the second conductivity type formed on the second buried layer (
6), the second buried layer (6) is covered, and the end portion is covered with the first buried layer (6).
A highly concentrated first layer formed in contact with the buried layer (5).
a third buried layer (7) of a conductive type; and a third buried layer (7) that covers the third buried layer (7) and is formed such that an end thereof is in contact with the first buried layer (5). A buried semiconductor light emitting device comprising a fourth buried layer (8) of a first conductivity type having a lower concentration than the buried layer (7). (2) Formed so that the fourth buried layer (8) according to claim 1 is covered with the fourth buried layer (8), and the end portion is in contact with the first buried layer (5). A buried semiconductor light emitting device characterized in that a fifth buried layer (13) of a first conductivity type is formed with a higher concentration than the fourth buried layer (5).