Effects of thermal annealing on Ti/Al Ohmic contacts on quarternary n-Al₀.₀₈In₀.₀₈Ga₀.₈₄N alloy film

Ohmic contacts of Ti/Al have been fabricated on n-type Al₀.₀₈In₀.₀₈Ga₀.₈₄N to determine the specific contact resistivity (SCR) using transmission line method (TLM). The measurements are performed on Ti/Al contacts which have been annealed to various temperatures from 400-700ºC with times of 5, 15 and 35 minutes, where the electrical behaviors of each condition are compared. For relatively different annealing temperatures, substantial differences of the SCR values are observed between different duration samples. The changes in the surface morphology after the annealing treatment were examined using scanning electron microscopy (SEM). The study has resulted in producing contact from the Ti (200 nm)/Al (50 nm) metallization scheme with the lowest specific contact resistivity of ρc=0.054 Ωcm2 after annealing in nitrogen for 10 minutes (cumulated time of 15 minutes) at 400 ºC.