Ohmic contacts to AlGaN/GaN HEMTs: A Comparison of two different Ti/Al metal ratios

Abstract

Ohmic contacts formed with two different metal stacks; by varying the Ti/Al thickness ratio were rapid thermal annealed in the temperature range 740-820 °C for 30 seconds in N2 ambience. The ohmic contact formed with Ti/Al metal thickness ratio 1/5 showed lower Rc values and smoother surface morphology compared to the contact with Ti/Al metal thickness ratio 1/1.5. The difference in behavior for both the contacts was corroborated with the outcome of different metallurgical reactions as observed by X-ray diffraction (XRD) and Energy dispersive X-ray analysis (EDX).