Surface Modification and Ohmic Contact Formation to n and p-Type GaN

Abstract

Surface modification of n and p-type GaN using Cl2/N2 and pure N2 plasmas was investigated. It was found that the surface conductivity of n-GaN was reduced when N2 was introduced, as N2 loss was prevented. However, the restoration of stoichiometry improved the resistivity of Ohmic contacts, as N2 was necessary for the formation of TiN. In contrast, N2 plasma exposure was beneficial to improvements of surface conductivities in p-GaN. Contacts deposited on Cl2/N2 etched surfaces exhibit excellent Ohmic characteristics.