Surface modification and ohmic contact formation to n and p-type GaN

Surface modification of n and p-type GaN using Cl-2/N-2 and pure N-2 plasmas was investigated. It was found that the surface conductivity of n-GaN was reduced when N-2 was introduced, as N-2 loss was prevented. However, the restoration of stoichiometry improved the resistivity of Ohmic contacts, as N-2 was necessary for the formation of TiN. In contrast, N-2 plasma exposure was beneficial to improvements of surface conductivities in p-GaN. Contacts deposited on Cl-2/N-2 etched surfaces exhibit excellent Ohmic characteristics.