JPH02288273A - Light emitting diode - Google Patents

Abstract

PURPOSE:To obtain a light emitting diode having high productivity by electrically isolating between a first electrode in which a current flows to the partial region of an active layer and a second electrode electrically connected to a block layer via layers from the block layer to the depth of the active layer. CONSTITUTION:When a diode is manufactured, an active layer 2 made of P-type GaAs, a second clad layer 3 made of P-type Al0.35Ga0.65As, and a block layer 4 made of a N-type Al0.15Ga0.85As are sequentially laminated on a clad layer made of a N-type Al0.35Ga0.65As, An is diffused at the central region of the layer 4 to form a diffused region 5. Then, when a groove is formed around the diffused region, a groove for isolating at the outside of the groove is also formed, but the depths of the grooves are formed together to reach the layer 1. Further, a P-type side electrode 6 is formed on the region 5, a monitoring electrode 7 is formed outside the groove around the region 5, and a N-type side electrode 8 is formed on the surface of the layer 1. A light emitting window is opened at the electrode 8 to form a reflection preventive film 10, and then isolated by the groove of the outside. Accordingly, its productivity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light emitting diode, and more particularly to a back-emission type high-brightness light emitting diode for optical fiber communication.

[Conventional technology]

FIG. 3 shows an example of a conventional light emitting diode for optical fiber communication. n-type A (l
On top of the first cladding layer (1), there are an active layer (2) of p-type GaAs, a second cladding layer (3) of p-type Aβ, Ga+-XA3, and a block layer (3) of n-type ANyGa+-yAs. 4) are sequentially stacked, and by diffusing Zn into a part of the block layer (4), the conductivity type of the diffusion region (5) is changed to p-type, and the conductivity type of the active layer is passed through the diffusion region (5). A current is concentrated in a partial region (a portion below the diffusion region), and luminescence with brightness is obtained.

Furthermore, when assembling the light emitting diode into a package in order to efficiently dissipate heat generated from the light emitting part, the light emitting diode is mounted with the block layer (4) side facing the package. Therefore, the light from the light emitting part is transmitted to the electrode on the first cladding layer (1) side (
8) The light extraction window is opened and the light is extracted from there.

[Problem to be solved by the invention]

Before separating the conventional light emitting diodes mentioned above,
In other words, when selecting the characteristics of a wafer with a large number of light emitting diodes, it is first necessary to electrically isolate it from neighboring pellets.
The electrode (8) on the 1) side is far away from the active layer (2) and is difficult to separate. If it is to be separated, it must be separated from the electrode (6) on the side closer to the active layer (2), that is, the side on which it is mounted, the block layer (4>).

When selecting characteristics of light emitting diodes that are electrically isolated from the block layer (4) side in a wafer state, set the wafer on a stage with the first cladding layer (1) side facing down, and separate each light emitting diode. Block layer (4
) A measuring probe is applied to the electrode on the side of the stage, and a voltage is applied between the probe and the stage to perform measurements. Although electrical characteristics can be measured with this method, optical characteristics such as emission intensity cannot be selected because the light extraction window faces the stage side.

As explained above, conventional light emitting diodes cannot be subjected to optical property zero screening in the wafer state, and in order to perform optical property screening, the optical properties must be measured one by one after being separated. However, it has the disadvantage that it is very time-consuming.

An object of the present invention is to solve these problems and provide a highly productive light emitting diode whose optical characteristics can be measured even in a wafer state.

[Means to solve the problem]

The light emitting diode of the present invention has, in addition to the first electrode for causing current to flow concentratedly in a partial region of the active layer, one or more electrodes in the same cladding layer where the first electrode is formed. , and is characterized in that at least the active layer is electrically isolated between the respective electrodes.

That is, a first cladding layer made of a semiconductor of at least a first conductivity type, an active layer made of a semiconductor whose forbidden band width is smaller than that of the first cladding layer, and a second conductivity type whose forbidden band width is larger than that of the active layer. It has a multilayer structure in which a second cladding layer made of a semiconductor of a first conductivity type and a block layer made of a first conductivity type semiconductor are sequentially laminated, and a second cladding layer made of a semiconductor of a first conductivity type is laminated in order, and a second cladding layer made of a semiconductor of a first conductivity type is laminated in order, and a second cladding layer made of a semiconductor of a first conductivity type is laminated in order. 1 electrode and a second electrode electrically connected to a block layer, and between the first electrode and the second electrode, electrical connection is made in each layer at least from the block layer to the depth of the active layer. It is structured so that it is separated into

[Example 1] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention.

A p-type Ga layer with a thickness of 2 μm is deposited on the first cladding layer (1) made of n-type A (10,35G ao, 65A S).
Active layer made of As (2>, p-type A- with a thickness of 1.5 μm
Ro, 35G a [1,65A Second cladding layer (3) consisting of S, 1.5 um thick n-type A II g,
Block layer (4
) are sequentially stacked, and Zn is diffused in a 30 μm diameter region at the center of the block layer (4) so that the diffusion tip remains in the second block layer (3) to form a diffusion region (5). Next, a groove is formed around the diffusion region, and at the same time, a groove is also formed outside the groove to separate the adjacent light emitting diode.

Both grooves are formed to a depth that reaches the first cladding layer (1). Furthermore, a p-side electrode (first
(6)), a monitor electrode (second electrode, (7)) on the outside of the groove around the diffusion region (5), and an n-side electrode (8) on the surface of the first cladding layer (1). form.

A light extraction window is opened in the n-side type i (8), and an anti-reflection film (10) is formed on the window portion in order to increase the light extraction efficiency. Thereafter, the light emitting diodes are separated one by one using an outer groove.

To select the characteristics of the above-mentioned light emitting diodes in wafer state, place them on a stage with the block layer (4) side facing up.
A probe is applied to the p-side electrode (6) to measure electrical characteristics such as reverse drive voltage and reverse leakage current. When the probe is also placed on the monitor electrode (7) and a negative voltage is applied to the n-side electrode (8), the first cladding layer (1) and the active layer (2)
Almost no current flows as it is because a reverse voltage is applied to the pn junction between the n-side electrode (6).
When more current is applied to emit light, the light from the light emitting part (the active layer region under the diffusion region) passes through the groove around the diffusion region (5), is reflected by the n-side electrode (8), and reaches the monitor electrode ( Since the current reaches the active layer 2) on the side where 7) is provided and is absorbed, the current corresponding to the emission intensity becomes the monitor voltage f! f! Flows to (7). This can be used to select the emission intensity. Furthermore, when assembling the above-mentioned light emitting diode into a package, it is mounted with the flock layer (4) side facing the package, so the same bias is always applied to the n-side electrode (6) and monitor electrode (7) after assembly. be done. However, since there is a blocking layer on the monitor electrode side, only a very weak current flows, and it has almost no effect on the luminous intensity.

[Example 2] FIG. 2 is a sectional view of Example 2 of the present invention, and the laminated structure is the same as Example 1. In this example, a groove with a depth reaching the first cladding layer (1) is formed around the central circular region of 30 μmφ, and only on the surface of the circular region is the n-side electrode (first electrode, ( 6))), a current is concentrated in a partial region of the active layer. Conventional light-emitting diodes of this type have the above-described structure and conduct current only through a portion of the active layer, so that no polarization layer is required. However, in this Example 2, since the monitor electrode (second electrode, (7)) is formed outside the groove, a blocking layer (4) is formed to prevent current from flowing to the monitor part after assembly, and the block layer (4) is formed near the light emitting part. Zn is diffused to form a diffusion region (5
), the conductivity type of the block layer (4) is changed to p-type. In addition, since it is difficult to separate the n-side electrode (6) and the monitor electrode (7) in the central circular region or groove, they are separated outside the groove, and the semiconductor crystal is separated outside the diffusion region (5). An insulating film made of SiO2 (
9) is formed. In Example 2, the light from the light emitting part (the active layer region surrounded by the groove) does not pass through the groove and enter the active layer (monitor part) on the side where the monitor electrode is formed, but the n-side electrode (8) and enters the monitor section, and the luminous intensity can be measured in the same manner as in Example 1 shown in FIG.

In the above embodiments, G a A s / A
ρGaAs-based semiconductor materials are used, but InP/
It can also be made in combination with other semiconductor materials such as InGaAsP.

[Effects of the Invention] As explained above, the present invention has an electrode on the block layer in addition to an electrode for supplying a concentrated current to a partial region of the active layer, and the space between the two electrodes is located deep in the active layer. Because they were previously electrically isolated, even high-brightness light-emitting diodes for optical fiber communication, in which the surface close to the active layer of the light-emitting diode is mounted toward the package, can produce a large number of light-emitting lights without affecting the characteristics after assembly. It is now possible to select characteristics including light emission intensity in a wafer state where diodes are formed in a row.
The labor involved in sorting can be significantly reduced, resulting in a significant improvement in productivity.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a light emitting diode of the present invention, and FIG. 3 is a cross-sectional view of a conventional light emitting diode. DESCRIPTION OF SYMBOLS 1... First cladding layer, 2... Active layer, 3... Second cladding layer, 4... Block layer, 5... Diffusion region, 6... First electrode (n-side electrode ), 7... second electrode (
monitor electrode), 8... n-side electrode, 9... SiO2 film, 10... antireflection film.

Claims (1)

[Claims] a first cladding layer made of a semiconductor of at least a first conductivity type; an active layer made of a semiconductor having a narrower bandgap width than the first cladding layer; and a semiconductor of a second conductivity type having a larger bandgap width than the active layer. The active layer has a multilayer structure in which a second cladding layer made of a semiconductor and a block layer made of a first conductivity type semiconductor are sequentially laminated, and a current injection means that allows current to flow intensively into a partial region of the active layer. The light emitting diode has a first electrode on the block layer for flowing a current to a partial region of the active layer, and a second electrode electrically connected to the block layer, and the first electrode and the A light emitting diode, wherein the second electrodes are electrically isolated from each other at least in each layer from the blocking layer to the depth of the active layer.