Investigation of Pd/Ti/Al and Ti/Al Ohmic contact materials on Ga-face and N-face surfaces of n-type GaN

摘要

Pd/Ti/Al and Ti/Al Ohmic contact materials on Ga-face and N-face surfaces of n-type GaN were investigated by measuring the contact resistivities with respect to annealing temperatures. Pd/Ti/Al contact showed good Ohmic property in contrast to Ti/Al contact on N-face surface of n-type GaN. Cross-sectional transmission electron microscopy results on samples of as-deposited and annealed at 450℃ for 30 s indicated that Pd played an important role in changing the surface state of N-face surface of n-type GaN and less than 50 A of Pd was required to obtain the best Ohmic contact property.