Effects of N[sub 2]O Plasma Surface Treatment on the Electrical and Ohmic Contact Properties of n-Type GaN

An plasma surface treatment was introduced to improve the electrical and ohmic contact properties of the n-GaN surface. Hall measurements indicate that the sheet carrier concentration and sheet resistance of the treated n-GaN is considerably improved compared to as-grown samples. In addition, it is shown that the Ti/Al contact on the plasma surface-treated GaN results in a significant reduction in the specific contact resistance by about one order of magnitude, compared to that for a conventionally treated GaN. Based on the Hall measurement and Auger electron spectroscopy data, the observed improvements in the electrical and contact properties are due to the formation of a layer of highly conductive gallium oxynitride at the surface.