| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that it is difficult to form a good ohmic junction because machining process causes to damage the surface of a p-type nitride semiconductor. SOLUTION: A defect layer 2 where a large number of defects exist on the interface of p-type GaN 1 touching Pd 3 is generated when the Pd 3 is simply deposited on the p-type GaN 1 damaged by machining process and a good ohmic junction cannot be formed (a). When it is heat treated at about 500 deg.C, the Pd 3 is diffused into the p-type GaN 1, and a PdGa compound 4 exhibiting metallic properties is formed in the p-type GaN 1 between the p-type GaN 1 and the Pd 3. Since no defect exist on the interface of the p-type GaN 1 touching the Pd 3, good ohmic characteristics can be attained (b). When the heat treatment temperature is increased, the PdGa 4 is destroyed and the Pd 3 is further diffused into the p-type GaN 1 to generate defects therein, thus causing deterioration of ohmic characteristics (c). |
