Al thickness influence on optimal annealing temperature of Ta/Ti/Al/Mo/Au ohmic contacts to AlGaN/GaN

Process flow of Ta/Ti/Al/Mo/Au ohmic contacts formation to AlGaN/GaN heterostructures was developed. Correlation between Al thickness and optimal ohmic contact annealing temperature was obtained. Optimal Ta:Ti:Al:Mo:Au metal ratio was obtained for two different types of AlGaN/GaN heterostructures. Ohmic contacts fabricated in developed process flow show good surface morphology and contact resistance less than 0.5 Ohm/mm.