Light-emitting semiconductor device and method of fabrication

Abstract

A low-resistance silicon baseplate (11) has formed thereon a buffer layer 12 in the form of an alternating lamination of AlN sublayers (12a) and GaN sublayers (12b). On this buffer layer there are formed an n-type semiconductor region (13) of gallium nitride, an active layer (14) of gallium indium nitride, and a p-type semiconductor region (15) of galliumnitride, in that order. An anode (17) is formed on the p-type semiconductor region (15), and a cathode (18) on the baseplate (11).

Description

TECHNICAL FIELD [0001] This invention relates to a light-emitting semiconductor device composed primarily of gallium nitride (GaN)-based semiconductors, and to a method of making the same. BACKGROUND ART [0002] The compound semiconductors composed primarily of GaN have been used extensively for fabrication of light-emitting devices such as diodes that are capable of glowing in blue. Examples of such compound semiconductors include, in addition to GaN itself, gallium aluminum nitride (GaAlN), indium gallium nitride (InGaN), and indium gallium aluminum nitride (InGaAlN). [0003] A typical prior art light-emitting device of the kind under consideration comprises a baseplate of electrically insulating material such as sapphire, a buffer layer overlying the baseplate and composed for example of GaxAl1-xN, where x is greater than zero and not greater than one (as taught by Japanese Unexamined Patent Publication No. 4-297023), an n-type semiconductor region of GaN or other compound semicond...

AI Technical Summary

Benefits of technology

[0016] The invention as set forth above yields the following advantages:

[0025] The invention of claim 5 enables an easy and inexpensive fabrication of the light-emitting semiconductor device of the improved performance characteristics.

Problems solved by technology

The noted sapphire baseplate of the light-emitting devices has been a cause of trouble in such dicing of the wafers because of its extreme hardness.

Sapphire itself is expensive, moreover, adding much to the manufacturing costs of the light-emitting devices.

There have been additional difficulties in connection with the sapphire baseplate.

The results were a greater surface area of the semiconductor and a corresponding increase in the costs of the light-emitting devices.

A further inconvenience arose from the fact that current flows through the n-type semiconductor region not only vertically (normal to the plane of the sapphire baseplate) but horizontally (parallel to the sapphire baseplate plane).

A still further inconvenience concerns the etching-away of parts of the active layer and p-type semiconductor region in order to expose part of the n-type semiconductor region for connection to the cathode.

Offsetting these advantages, however, is the fact that SiC is even more expensive than sapphire.

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