Electroless nickel/gold Ohmic contacts to p -type GaN

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 ρ c in the region of 10 − 2 Ω 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.