Electroless nickel/gold Ohmic contacts to p-type GaN

Abstract

A solution based approach to forming Ohmic contacts to p-type GaN is described. Electroless plated Ni/Au contacts are shown to compare favorably with traditional evaporated contacts, with contact resistivities rho(c) in the region of 10(-2) Omega cm(2). These values are readily achieved after a rapid thermal annealing in an O-2 atmosphere. The tunneling nature of the contact is confirmed via temperature dependant measurements. X-ray diffraction measurements confirm the similarity between evaporated and plated contacts. Current-photocurrent (I-L) and current-voltage (I-V) measurements from light emitting diodes formed using an electroless p-type contact are shown. Electroless deposition of the contact metals allows for a reduction in processing time and cost.