| 摘要 |
A method of forming a light-transmissive contact on a p-type Gallium nitride (GaN) layer (20) of an optoelectronic device (10) includes introducing a selected metal (24) in an oxidized condition, rather than oxidizing the metal only after it has been deposited on the surface of the p-type GaN layer. In some applications, the oxidized metal provides sufficient lateral conductivity to eliminate the conventional requirement of a second highly conductive contact metal, such as gold. If the second contact metal (38) is desired, an anneal 40 in an oxygen-free environment is performed after deposition of the second layer. The anneal causes the second metal to penetrate the oxidized metal and to fuse to the surface of the p-type GaN layer Alternatively, the oxidation occurs only after at least one of the two metals is deposited on the surface of the p-type GaN layer. In which case the two metals are deposited and the oxidation occurs in an environment that includes both water vapor and oxygen gas (52). In the alternative method the first metallic layer maybe deposited and then oxidized throughout its depth. The second material, such as gold, is evaporated on the first material and a re-anneal step is performed to drive the second metal through the oxidized first metal. In either method, a pattern of windows may be formed in the resulting contact structure or in additional layers that are formed thereon.
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