AlGaN/GaN High-Electron-Mobility Transistors Fabricated Through a Au-Free Technology

This letter reports undoped AlGaN/GaN high-electron-mobility transistors (HEMTs) fabricated with a Si-CMOS-compatible technology based on Ti/Al/W ohmic and Schottky contacts. The use of ohmic recess is key to reduce the contact resistance of this Au-free metallization below 0.5 Ω·mm. Comparison of HEMTs fabricated on the same wafer with and without ohmic recess shows that the recess provides a tenfold reduction in contact resistance, resulting in a fivefold lower forward voltage drop at I_DS = 100 mA/mm. The reported Au-free AlGaN/GaN HEMT fabrication technology provides similar performance (i.e., contact resistance, leakage current, and breakdown voltage) than state-of-the-art Au-based AlGaN/GaN HEMTs and can be used in standard Si fabs without the risk of contamination.