JPH01179374A - Junction semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To manufacture a light emitting element easily and not only attain high intensity but also improve heat radiation properties, by providing an insulation layer at one side of a semiconductor substrate and forming a groove at least at its layer so that the semiconductor substrate can be exposed, thereby forming semiconductor layers including active layers on the insulation layer respectively in such a way that each groove is coated. CONSTITUTION:An insulating layer is provided by a masking agent on an n-type GaAs substrate B and the insulation layer 1 is equipped with 12 places of circular grooves 7 which expose the substrate B at equal intervals one another. This element allows an n-type AlGaAs clad layer 2, an n-type AlGaAs active layer 3, and a p-type AlGaAs layer 4 to perform an epitaxial growth in order so as to coat each groove 7. Thus, semiconductor layers P having a multilayer structure consisting of double-hetero junction are formed respectively on the insulation layer 1. Then, an electrode E1 as one of electrode materials at a p-side is arranged at the surface of the clad layer 4 with the exception of a top part and also the electrode E2 as one of the electrode materials at an n-side is arranged at the lower face of the substrate B by means of vacuum vaporization and the like. Thus, a semiconductor light emitting element is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel surface-emitting type semiconductor light emitting device that can be used as a light emitting diode or a semiconductor laser.

[Conventional technology]

Light emitting diodes (LEDs), especially communication LEDs
LEDs differ from display LEDs in terms of high brightness and high-speed response, and while the light-emitting layer is mainly homojunction for display purposes, single heterojunction or double heterojunction structures are mainly used for communication purposes. It is being

Communication LEDs vary depending on how light is extracted from the light emitting area.
The surface-emitting type, which is classified into the surface-emitting type and the edge-emitting type, has a structure that extracts light in a direction perpendicular to the bonding surface, and current confinement is performed only in an active region with an area smaller than the core diameter of the optical fiber. Obtaining brightness.

A feature of this surface-emitting type LED is that light from the active region can be extracted to the outside with almost no self-absorption loss.

The edge-emitting type has a structure that extracts light in a direction parallel to the junction surface of the epitaxial layer, and has a structure similar to that of a semiconductor laser, except that the active layer thickness is increased to reduce the gain per unit length. Current constriction is being attempted. The features of this edge-emitting type LED are that high brightness can be obtained with a relatively low current density, and that monitor light can also be extracted from the side directly opposite to the emitted light. However, since the light from inside propagates through the active region with a large absorption coefficient and reaches the end facets, the self-absorption loss is large.In order to effectively reduce this self-absorption loss,
Some LEDs have a light guide layer adjacent to the active layer.

On the other hand, in semiconductor lasers (laser diodes, LDs), the LD type is basically a gain waveguide type that can be made only with a current confinement path, and a refractive index waveguide type that is built in, or a built-in type with a completely buried waveguide side surface. It can be roughly divided into refractive index waveguide types. Most LD optical waveguides also serve as the active layer,
A double heterostructure having a Keyria injection, confinement mechanism, and a confinement waveguide mechanism for optical electric field distribution is often used. In the double-hetero multilayer structure, various stripe formation methods are employed to confine carriers and light in a direction perpendicular to the layer.

[Problem to be solved by the invention]

In both light-emitting diodes and semiconductor lasers, high brightness is achieved by improving the efficiency of carrier injection into the active region, and the heat generated in the light-emitting region (especially the light-emitting region of embedded light-emitting elements) is efficiently dissipated, and the active region is The emergence of a semiconductor light emitting device that allows the shape of the layers to be changed simply and easily, and in combination with a structure that realizes this, facilitates the fabrication of the device itself and enables mass production, is eagerly awaited.

Therefore, an object of the present invention is to provide a light-emitting element such as a semiconductor laser or a light-emitting diode that is easy to manufacture, allows the shape of the active layer to be changed arbitrarily, and improves the efficiency of current injection into the active layer to achieve high brightness. At the same time, it is an object of the present invention to provide a novel junction-type semiconductor light-emitting device that has superior heat dissipation properties, especially compared to embedded-type light-emitting devices.

[Means to solve the problem]

The purpose is to provide an insulating layer on one side of a semiconductor substrate, form at least one groove in the insulating layer to expose the semiconductor substrate, and place a semiconductor layer including an active layer on the insulating layer so as to cover the multiple grooves. This is achieved by a junction type semiconductor light emitting device characterized in that an upper electrode is formed on the semiconductor layer, and a lower electrode with a polarity different from that of the upper electrode is provided on the other side of the semiconductor substrate.

The semiconductor light emitting device of the present invention has a structure in which at least one groove exposing the substrate is formed in an insulating layer on a semiconductor substrate, and a semiconductor layer including an active layer is formed on the insulating layer so as to cover this groove. As shown in the example below, which describes an example of the manufacturing process, it is very easy to manufacture, and the shape of the active layer can be varied in various ways due to its structure. In particular, it has excellent heat dissipation compared to a buried type light emitting element. Furthermore, by forming a large number of grooves in an insulating layer on a semiconductor substrate and forming a semiconductor layer for each groove, a light emitting element with an array structure can be easily obtained.When using this for optical fiber communication, A two-dimensional array with optical fibers can be created by simply coupling optical fibers to each semiconductor layer.

The semiconductor material used in the light emitting device of the present invention is not particularly limited, and may be any material commonly used in semiconductor lasers and light emitting diodes, such as GaAs, GaP, AlGaAs, and InP, which are ■-■ group compound semiconductors.
, InGaAsP, InGaP, InAIP
, GaAsP, GaN.

Zn5e, ZnS, ZnO, C which are II-Vl group compound semiconductors such as InAsP and InAsSb
There are dSe, CdTe, etc., IV-Vl group compound semiconductors such as PbTe, Pb5nTe, Pb5nSe, etc., and rV-IV group compound semiconductors such as SiC, and each material can be applied by taking advantage of its advantages. To specifically list some combinations of materials, the materials of the insulating layer provided on the semiconductor substrate are Sing,
SiNx, 5iOxNy-amorphous-5i, A
The semiconductor substrate for forming this insulating layer and the semiconductor layer including the active layer provided on the insulating layer using hOs etc. are as follows: Material of the semiconductor substrate Material of the second conductor layer ■ GaAs: Ga, Ir++-xPyA3+
-y, (AlGaAsJylnl-yP -, A1.G
a+-, As■ InP: Gaxlr+1-
xPyAs+-y \(AIJa+-Jyln+-yA
3 ■ GaSb: In(PJ3+-JySb+-
y, Ga114n+-NAsySb+-y ■ GaAs+-aPa/GaAs5 GaP:
(AIxGa+-Jylr++-yP, etc.)

〔Example〕

Hereinafter, the junction type semiconductor light emitting device of the present invention will be explained based on Examples.

An embodiment of the semiconductor light emitting device of the present invention is shown in FIGS. 1 and 2. In this light emitting device, dome-shaped semiconductor layers P are provided at 12 locations on an insulating layer 1 provided on an n-type GaAs substrate B. It is a two-dimensional array shaped like As is clear from FIG. 2 showing the cross-sectional shape of each semiconductor layer P,
A circular groove 7 exposing the substrate B is formed in the insulating layer 1,
An n-type AlGaAs cladding layer 2 (A1 composition ratio 0.4), an n-type AlGaAs active layer 3 (^l&ll composition ratio 0.01), and a p-type ^lGaAs are formed on the insulating layer 1 so as to cover the groove 7.
A cladding 114 (A1 composition ratio 0.4) is epitaxially grown in order, and these layers 2.3.4 form a semiconductor layer P.
It consists of P is applied to the surface of the cladding layer 4 other than the top.
A side electrode E1 and an n-side electrode E2 are provided on the lower surface of the substrate B, respectively.

When the light emitting element of this embodiment is used, as shown in FIG. 3, the electrode E2 side is attached to a heat sink 20 which also serves as an electrode. Generally, the heat sink 20 is made of St.
Consists of Cu, BeO, SiC, diamond, etc.
For attachment, use a low melting point metal (In, Sn, etc.) or bonding solder (Pb-Sn, Au-5n.

Au-5i, etc.) are used. Here electrode E1.82
When a current is injected between them, carriers are efficiently injected and confined within the active layer 3, and light is emitted from the top of the semiconductor layer P in a direction substantially perpendicular to the substrate B. That is, the current is injected from the p-side electrode El through the cladding layer 4 into the active layer 3, and after contributing to light emission by carrier recombination in the active region, the current flows through the cladding layer 2, the groove 7 formed in the insulating layer l, and the substrate. It flows through B to the n-side type iE2.

In this light emitting device, current is uniformly and efficiently injected into the active layer 3 due to its structure, and the insulating layer 1 prevents current from flowing into portions not involved in light emission.

When used for optical fiber communication, a semiconductor layer P is formed in a dome shape with the same diameter as the optical fiber, and the end surface of the optical fiber connected to the semiconductor layer P is finished in a shape that can be fitted into the semiconductor layer P. Furthermore, by making the core diameter of the optical fiber and the top part of the cladding layer 4 where the electrode E1 is not provided the same size, the optical fiber and the light emitting element can be easily connected in a two-dimensional play shape, and the light emission from the semiconductor layer P can be is reliably transmitted to the optical fiber.

Such a light emitting element is a surface emitting type that emits light from the top of the semiconductor layer P in a direction perpendicular to the substrate B, but in the above embodiment as a light emitting diode, a cladding is used to emit light from the top of the semiconductor layer P. Although the electrode E1 is not provided on the top of the layer 4, it may be provided over the entire surface of the cladding layer 4 as long as it is a transparent electric bridge made of indium, titanium, oxide, or the like.

Alternatively, instead of using a light-absorbing GaAs substrate, for example, Al
Using a GaAs substrate, an electrode is provided on the entire surface of the cladding layer 4, and a through hole communicating with the groove 7 for removing the substrate B and i[E2 is formed directly below the groove 7, and the semiconductor layer P side is fitted with this through hole. If it is attached to a heat sink that has a concave portion of the same size and also serves as an electrode, light can be emitted from the substrate B in a direction substantially perpendicular to the substrate B.

Next, an example of a method for manufacturing a semiconductor light emitting device having the structure shown in FIG.
This will be explained with reference to Figures (a) to (e). Note that the substrate preferably has a (100) plane, but other planes such as a (111) A) plane may be used, and only one semiconductor layer is shown as a representative in the figure.

First, an insulating layer 1 is formed on an n-type GaAs substrate B (see FIG. 4(a)) with a masking agent (for example, SiO2, SiN4, etc., which can be applied by electron beam evaporation, sputtering, CVD, etc.). (Fig. 4(b))
), diameter 2 exposing the substrates B at equal distances from each other.
Twelve circular grooves 7 of approximately five sizes are formed in the insulating layer 1 (see FIG. 4(C)), and then liquid phase epitaxial growth (L
The n-type AlGaAs cladding layer 2 (
Het! Il composition ratio 0.4), n-type GaAs active layer 3
(A1 composition ratio 0.01) and ρ-type AlGaAs layer 4 (
A1 composition ratio 0.4) is sequentially grown epitaxially to form multi-N structure semiconductor layers P having a double heterojunction on the insulating layer 1 (see FIG. 4(d)). Then, on the surface other than the top of the cladding layer 4, an electrode E1 made of, for example, Cr-Au or AuZn is placed as a p-side electrode material.
Further, as an n-side electrode material on the lower surface of the substrate B, for example, N+-
A semiconductor light emitting device having the structure shown in FIG. 1 is manufactured by providing electrodes E2 made of Au%AuGe by means such as vacuum evaporation (see FIG. 4(e)). When forming the electrode El, either remove only the unnecessary electrode at the top after providing it on the entire surface of the cladding layer 4, or, if a transparent electrode is used as described above, form the electrode on the entire surface of the cladding layer 4. Good too.

In practice, the obtained light emitting element may be attached by attaching its electrode E2 to the heat sink 20 by bonding or soldering, and wire bonding the electrode E1, as shown in the embodiment of FIG.

As can be understood from the manufacturing process, it is very easy to manufacture the device because it is only necessary to attach the electrodes after forming the double heterostructure semiconductor layer.

In addition, since the semiconductor layer is formed on the groove of the insulating layer, the shape of the active layer can be arbitrarily changed in the manufacturing process by appropriately selecting the plane orientation of the substrate and the thickness of each growth layer of the semiconductor layer. In other words, in the light emitting device of the present invention, various structures can be easily formed for confining carriers and light.

FIG. 5 shows a light emitting device according to another embodiment. This light emitting element has almost the same appearance as that shown in FIGS. 2 and 3, but uses a different semiconductor material and emits light from 11 iB'. Its structure is based on the AlGaAs substrate B
' (Al composition ratio 0.4) A circular groove 17 exposing the substrate B' is formed in the insulating layer 11 provided on the insulating layer 11 (Al composition ratio 0.4), and an n-type AlGaAs cladding layer 12 (AI composition ratio 0.4), p-type GaAs active layer 13 and p-type AlGaAs layer 14 (AI composition ratio 0.4).
4) are epitaxially grown in order, and an n-side electrode E2 is provided on the surface of the substrate B° other than the portion facing the active layer 13. When using the
A UL film 15 is formed on the surfaces of the semiconductor layer P' and the insulating layer 11, and bonding solder (Au Sn, etc.) is further applied.
1 having a recess into which the semiconductor NP° is approximately fitted via 16;
The semiconductor layer P' side is attached to a heat sink 21 which also serves as a scratch. In this embodiment, since the semiconductor NP' side having the active layer 13, which is a heat generating portion, is attached to the heat sink 21, heat is immediately transmitted from the semiconductor layer P' to the heat sink 21, resulting in excellent heat dissipation.

The present invention is not limited to the above embodiments, and other embodiments may be adopted as long as they do not depart from the purpose of the present invention.
For example, the shape of the semiconductor layer formed on the insulating layer does not have to be dome-shaped, and may be any other shape such as a rectangular shape. Further, the electrodes E1 and E2 are not limited to the size and shape shown in the embodiments, but can be provided in any size and shape as long as current can be efficiently injected into the active layer.

〔Effect of the invention〕

As is clear from the above, in the junction type semiconductor light emitting device of the present invention, at least one groove exposing the substrate is formed in the insulating layer on the semiconductor substrate, and the semiconductor layer including the active layer is insulated so as to cover the valley groove. By forming each layer on the active layer, current injection efficiency into the active layer is improved, carriers are efficiently confined in the active region, and as is clear from the manufacturing process, the device is easy to manufacture, and a large amount of It is easy to produce, the shape of the active layer can be changed relatively easily, and it has superior heat dissipation compared to ordinary embedded light emitting elements. Furthermore, the array structure in which semiconductor layers are formed for a large number of grooves and grooves allows easy coupling with optical fibers in a two-dimensional array when applied to optical fiber communications, making it very useful in practice.

[Brief explanation of the drawing]

1 is a perspective view of an embodiment of the junction type semiconductor light emitting device of the present invention, FIG. 2 is a partially omitted sectional view of the light emitting device in FIG. Partially omitted cross-sectional views when the light emitting element is attached to the heat sink, Figures 4(a) to (e)
) is a flowchart showing an example of the manufacturing process of the light emitting device shown in FIG. 1, and FIG. 5 is a sectional view with the negative part omitted when the light emitting device of another embodiment is attached to a heat sink. B, B'': Substrate P, P': Semiconductor layer 1, 11: Insulating layer 2-4. 12-14: Epitaxial growth layer El
:p@electrode E2 :n side electrode 7.17: groove 20.21: heat sink 8 □1 Figure 2

Claims (1)

[Claims] providing an insulating layer on one side of the semiconductor substrate, forming at least one groove in the insulating layer to expose the semiconductor substrate, forming a semiconductor layer including an active layer on the insulating layer so as to cover each groove; A junction type semiconductor light emitting device characterized in that an upper electrode is provided on a semiconductor layer, and a lower electrode with a polarity different from that of the upper electrode is provided on the other side of the semiconductor substrate.