Thermal stability of Ohmic contacts to InN

Abstract

Ti ∕ Al ∕ Ni ∕ Au and Ti∕Al∕TiB2∕Ti∕Au Ohmic contacts on n-type InN were investigated as a function of annealing temperature. A minimum specific contact resistance of 1.6×10−6Ωcm−2 was obtained for the TiB2-based Ohmic contacts on n-type GaN with n∼1018cm−3 after annealing at 900°C. The minimum value with the Ni-based metallization was higher (6×10−6Ωcm2). The measurement temperature dependence of contact resistance was similar for both Ti∕Al∕TiB2∕Ti∕Au and Ti∕Al∕Ni∕Au, suggesting that the same transport mechanism was present in both types of contacts. The TiB2-based Ohmic contacts displayed superior thermal stability, suggesting that it is a superior diffusion barrier at these temperatures than Ni.