Formation of low resistance nonalloyed ohmic contacts to p-type GaN by KrF laser irradiation

摘要

KrF excimer-laser-irradiation treatment in a N_2 atmosphere is introduced to improve the electrical properties of p-type GaN and so to form low resistance nonalloyed Ni/Au ohmic contacts. The as-grown sample exhibits non-linear electrical behavior. However, the samples laser-annealed in N_2 ambient become ohmic with specific contact resistance of 8.9( ± 0.6) x 10~(-5) Ωcm~2. Hall measurement and current-voltage-temperature results show that the laser irradiation is effective in increasing a hole concentration in the surface region of p-GaN, leading to both the enhancement in field emission and the reduction of the effective Schottky barrier heights at the metal-semiconductor interface.