Thermal stability of W ohmic contacts to n-type GaN

W was found to produce low specific contact resistance (rho(c) similar to 8.0X10(-5) Ohm cm(2)) ohmic contacts to n(+)-GaN (n=1.5X10(19) cm(-3)) with limited reaction between the metal and semiconductor up to 1000 degrees C. The formation of the beta-W2N and W-N interfacial phases were deemed responsible for the electrical integrity observed at these annealing temperatures. No Ga out-diffusion was observed on the surface of thin (500 Angstrom) W contacts even after 1000 degrees C, 1 min anneals. Thus, W appears to be a stable contact to n(+)-GaN for high temperature applications. (C) 1996 American Institute of Physics.