Achieving A Low Contact Resistivity of 0.11 Ω·mm for Ti5Al1/TiN S/D Contact on Al0.2Ga0.8N/ AlN/GaN Structure without Barrier Recess

In this paper, we demonstrated a gold-free Ti5Al1 /TiN source and drain (S/D) contact on non-recessed AlGaN/AlN/GaN structure. Compared to the conventional gold-based (Ti/Al/Ti/ Au and Ta/ Al/Au) or multilayer gold-free (Ti/Al/TiN and Ta/Al/Ta) S/D contact metals, using a Ti5Al1/TiN (60 nm/60 nm) dual-layer contact metal, a low contact resistivity of 0.11 \Omega\cdot \text{mm was achieved after 920 °C/ 60 s annealing in nitrogen ambient. It was found that Al out-diffusion from AlGaN was suppressed while a thin TiN layer and n-AlGaN layer was formed at the interface, which were beneficial for the low contact resistivity S/D contact formation.