JPH0738146A - Semiconductor light emitting device - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a high-power semiconductor light-emitting device with improved light extraction efficiency. [Structure] p-GaAlAs cladding layer 2, n-GaA
In the semiconductor light emitting device 1 including the 1As clad layer 4, the p-GaAlAs active layer 3 disposed between these clad layers 2 and 4, the lower electrode 7, the upper electrode 6, and the light extraction surface 5, the semiconductor light emitting device 1 does not serve as a light emitting region. The active layer was removed by etching, and the surface thereof was formed into an uneven surface 8 that diffusely reflects light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device such as a light emitting diode, and more particularly to a surface emitting semiconductor light emitting device.

[0002]

2. Description of the Related Art In recent years, a semiconductor light emitting device has been widely used as an optical communication device or a display device. For example, in order to enable highly efficient optical transmission, a larger light output can be obtained with a smaller current. There is a demand for a high-power semiconductor light emitting device with high luminous efficiency.

FIG. 2 is a side sectional view showing the structure of an example of a conventional semiconductor light emitting device. 1. In FIG. 1, in a semiconductor light emitting device 21 of a conventional example, a p-GaAlAs clad layer 2, a p-GaAlAs active layer 3, and an n-GaAlAs clad layer 4 are sequentially epitaxially grown.
An annular electrode confinement groove 10 having a depth reaching from the aAlAs clad layer 4 to the p-GaAlAs clad layer 2 is formed, and a circular lower electrode 7 is formed on the lower surface of the separated n-GaAlAs clad layer 4. This current constriction groove 1
0 separates the light emitting region of the p-GaAlAs active layer 3 into a circular active layer 3a, and allows current to flow only in the active layer 3a, so as to obtain high output and efficient light emission. It is a thing. A circular light extraction surface 5 is formed on the upper surface of the p-GaAlAs cladding layer 2 and an upper electrode 6 is formed on the peripheral portion thereof. Then, a current is passed through the upper electrode 6 and the lower electrode 7, and the light emitted upward from the active layer 3a is emitted from the light extraction surface 5 to the outside.

[0004]

By the way, according to the conventional semiconductor light emitting device 21 having the above-mentioned structure, the cladding layer 2 has a larger bandgap than the active layer 3, so that the absorption coefficient at the emission wavelength is large. Light emitted in a very small amount is hardly absorbed. On the other hand, the active layer 3b outside the light emitting region separated by the current confinement groove 10 has a large absorption coefficient at the emission wavelength. In addition, since the refractive index of a semiconductor is about 3.5, which is very large, the light incident on the light extraction surface 5 with an inclination of about 17 ° or more from the vertical direction is totally reflected and cannot be directly extracted. . Therefore, when the light reflected by the light extraction surface 5 reaches the active layer 3b outside the light emitting region, it is almost absorbed and cannot be extracted, so that there is a problem that the light extraction efficiency is poor. Therefore, the present invention has been made in view of the above points, and an object of the present invention is to provide a high-power semiconductor light emitting device with improved light extraction efficiency.

[0005]

In a semiconductor light emitting device of the present invention, electrodes are formed above and below a semiconductor crystal layer including an active layer so that the active layer serves as a light emitting region and faces the active layer. On the surface side, in a surface emitting semiconductor light emitting device in which a light extraction surface for emitting light emitted from the light emitting area to the outside is formed, by configuring a portion other than the light emitting area on the active layer side as a diffuse reflection area, The above-mentioned object is achieved.

[0006]

Of the light emitted from the active layer and reflected by the light extraction surface, the light that reaches the irregular reflection area is irregularly reflected, and a part thereof is extracted outside from the light extraction surface.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The same reference numerals are used for the same components as those of the above-described conventional example or components corresponding to those of the conventional example. FIG. 1 is a side sectional view showing the structure of an embodiment of the semiconductor light emitting device of the present invention. In the figure, the semiconductor light emitting device 1 includes a p-GaAlAs cladding layer 2, a p-GaAlAs active layer 3 and an n-GaA on a substrate (not shown).
After the lAs clad layer 4 is sequentially grown by the liquid phase growth method, the substrate is removed. Next, on the surface of the p-GaAlAs cladding layer 2, an upper electrode 6 is formed on the peripheral portion thereof except for the circular light extraction surface 5. In addition, n-GaAlA
A circular lower electrode 7 is formed on the surface of the s clad layer 4,
Using this lower electrode as an etching mask, n-GaAl
Including the active layer outside the light emitting region from the As clad layer 4, p−
The GaAlAs cladding layer 2 is reached and etched.
This etching is performed using an etching solution such that the etched surface becomes the uneven surface 8 that diffusely reflects light.

Another method for forming the uneven surface 8 is to form a p-GaAlAs clad layer 2, a p-GaAlAs active layer 3 and an n-GaAlAs clad layer 4 on a substrate (not shown) by a liquid phase growth method. After sequentially growing, the substrate is removed. Next, a circular lower electrode 7 is formed n
-Mask the central part of the surface of the GaAlAs clad layer 4,
The n-GaAlAs clad layer 4 including the active layer outside the light emitting region is reached to the p-GaAlAs clad layer 2 for etching. On the surface of the p-GaAlAs clad layer 2,
The lower electrode 6 is formed on the peripheral portion except the circular light extraction surface 5. A circular lower electrode 7 is formed on the surface of the remaining masked n-GaAlAs cladding layer 4. Further, for example, an Au film is formed on the surface of the p-GaAlAs cladding layer 2 exposed by etching by a vapor deposition method,
Heat treatment is applied. Then, the p-GaAlAs cladding layer 2
At the interface between the Au film and the Au film, alloying occurs and an Au alloyed layer (not shown) is formed. When the Au film and the Au alloyed layer are removed by etching, an uneven surface 8 that diffusely reflects light is formed on the surface of the p-GaAlAs clad layer 2.

According to the semiconductor light emitting device 1 of one embodiment of the present invention having the above structure, most of the light emitted from the active layer, which is reflected by the light extraction surface 5, is absorbed. Without passing through the clad layer 2. Then, the light that has reached the uneven surface 8 is diffusely reflected there, and heads for the light extraction surface 5 again, and the light that is incident nearly vertically is extracted to the outside. By repeating such a process, the light extraction efficiency can be improved. As a result, the light output of the device can be increased.

The materials and manufacturing methods used in this embodiment are not limited to these, and can be changed as appropriate.

[0011]

As described above, according to the semiconductor light emitting device of the present invention, the light extraction efficiency is improved and the light output can be increased.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a structure of an embodiment of a semiconductor light emitting device of the present invention.

FIG. 2 is a side sectional view showing a structure of an example of a conventional semiconductor light emitting device.

[Explanation of symbols]

 1 Semiconductor Light-Emitting Device 2 p-GaAlAs Clad Layer (Semiconductor Crystal Layer) 3 p-GaAlAs Active Layer (Active Layer) 4 n-GaAlAs Clad Layer (Semiconductor Crystal Layer) 5 Light Extraction Surface 6 Upper Electrode (Electrode) 7 Lower Electrode ( Electrode) 8 Uneven surface (diffuse reflection area)

Claims (1)

[Claims] 1. An electrode is formed on an upper portion and a lower portion of a semiconductor crystal layer including an active layer, and the active layer serves as a light emitting region.
In a surface emitting semiconductor light emitting device having a light extraction surface for emitting light emitted from the light emitting region to the outside on the opposite surface side of the active layer, a portion other than the light emitting region on the active layer side is defined as a diffuse reflection region. A semiconductor light emitting device characterized by the above.