High temperature stable W and WSi_x contacts on n-and p-GaN

摘要

The thermal stability of W and WSi_x ohmic contacts on epi or ion-implanted P-and n-type GaN has been examined. In Si-implanted GaN annealed at => 1400 deg C, very high n-type doping levels have been obtaind (approx 5 x 10~(20) cm~(-3)) and good specific contact resistances are obtained for the rfractory metals (10~(-6) OMEGA -cm~2 range). However, implantation of Mg~+ only produces p-type doping levels in the low 10~(17) cn~(-3) range. On p-GaN, leaky Schottky diode behavior is observed for W, WSi_x and Ni/Au contacts at room temperature. As the hole concentration increases with measurement temperature, ohmic characteristics are obtained at 250-300 deg C, but R_c values are still typically in the 10~(-2) OMEGA -cm~2 range.