JPS6035832B2 - Electrode structure of semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrode structure applied to semiconductor devices such as compound semiconductor light emitting devices.

In GaAIAS light emitting diodes, laser diodes, etc., it is important to form ohmic electrodes reliably in order to improve luminous efficiency and obtain good device characteristics.
In particular, if the semiconductor layer in contact with the electrode layer is made of Ga. ★AIxAs
In the case of a mixed crystal layer, it becomes difficult to obtain good ohmic contact as the value of x increases. The present invention aims to provide an electrode structure for a semiconductor device, which is a new and useful developed technology that can obtain good ohmic contact when forming an ohmic electrode on the above-mentioned Ga, *AIX layer. This is the purpose.

below,. The present invention will be explained in detail according to examples. 1st
The figure is a configuration diagram of a semiconductor device showing a test sample of the present invention.

An n-type Ga, NAIX carrier layer 2 having a carrier concentration of 5×1 and 7 arc-3 is grown on a P-type GaAs substrate 1 to a thickness of about 20 m, and an electrode 3 with a diameter of 100 m is formed on the pitch interval 2 side. Form, 500 qo, 3 minutes a.

The resistance value between the electrodes 3 was measured. As a result, as shown in FIG. -xA1
When the x value of the xAs layer 2 was 0.3 or less, an ohmic contact could be formed with the normally used three-layer electrode of AuQ-Ni-Au, but when the x value became 0.3 or more, the electrode 3
The resistance increases rapidly, and it becomes impossible to obtain good ohmic contact as shown by curve 1. however,
For example, 0.3 to 0.4 wt% of S (sulfur) is added to the AuGe in contact with the Ga, ★AIxAs layer 2, and after vacuum deposition of about 3000 A by resistance heating, 1 % of Ni is added to prevent agglomeration.
About 2000A of Au is deposited to increase the poundability. After that 50000 and 3
When alloying was carried out for a minute and the interelectrode resistance was measured, as shown by curve 12, the resistance value did not increase even when the N mixed crystal ratio x increased, and good ohmic contact was obtained even when the x value was 0.8. Ta. Incidentally, data almost similar to curve 12 was obtained when S was contained in an amount of 0.1 to 2.0 wt%. Therefore, in a semiconductor device in which the contact layer with the electrode is composed of a GaAIAs layer, if the mixed crystal ratio of GaAIAs is relatively high, good optical properties can be achieved by forming the electrode with a sulfur-containing Au-based material. You can get mic contact. As described in detail above, according to the present invention, it is possible to obtain good ohmic contact by incorporating a small amount of sulfur into the material without significantly changing the conventional electrode structure, and therefore to have a high mixed crystal ratio. n-type GaAI
When attaching an electrode to the As layer, there is no need to newly insert an ohmic contact layer such as ◯aAs.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a semiconductor device showing a test sample of the present invention. FIG. 2 is a characteristic diagram showing the relationship between needle crystal ratio and interelectrode resistance value, explaining one embodiment of the present invention. 1...p-type Ga
As substrate, 2...n-type Ga, -xA1xAs layer, 3
·…··electrode. Figure 1 Figure 2

Claims (1)

[Claims] 1 A containing a trace amount of sulfur on the n-type GaAlAs layer
An electrode structure for a semiconductor device, characterized in that an n-type electrode is formed of an alloy material of u and Ge.