AlGaN/AlN/GaN High-Electron-Mobility Transistors Fabricated with Au-Free Technology

A Au-free technology was developed to fabricate AlGaN/AlN/GaN high-electron-mobility transistors (HEMTs) on Si substrates. Ohmic contact resistance of ∼0.6 Ω mm was achieved through a Ti/Al/Ni/Pt metal scheme annealed at 975 °C for 30 s in N2 atmosphere. The ohmic metal surface after annealing was very smooth, with a root-mean-square roughness of only 4.6 nm. The fabricated GaN HEMTs show an off-state breakdown voltage of 540 V with a gate-to-drain distance of 8 µm. These results demonstrate the potential of this Au-free GaN HEMT technology in power electronics and GaN-Si CMOS integration applications.