Chung-Yi Yu

A next generation CMOS-compatible GaN-on-Si transistors for high efficiency energy systems

CMOS-compatible 100 V / 650 V enhancement-mode high electron mobility transistors (E-HEMTs) and 650 V depletion-mode MISFET (D-MISFET) are fabricated on 6-inch GaN-on-Si wafers. These devices show excellent power converter switching performances. Both 100 V and 650 V E-HEMTs had passed industrial reliability qualifications. The importance of bulk leakage, interface quality and gate trapping in dynamic on-resistance is figured out. The device with optimized processes shows a significant reduction of the dynamic on-resistance degradation.

CMOS-compatible GaN-on-Si field-effect transistors for high voltage power applications

CMOS-compatible 100/650 V enhancement-mode FETs and 650 V depletion-mode MISFETs are fabricated on 6-inch AlGaN/GaN-on-Si wafers. They show high breakdown voltage and low specific on-resistance with good wafer uniformity. The importance of epitaxial quality is figured out in a key industrial item: high-temperature-reverse-bias-stress-induced on-state drain curent degradation. Optimization of epitaxial layers shows significant improvement of device reliability.

AlGaN/GaN MIS-HFET with improvement in high temperature gate bias stress-induced reliability

CMOS-compatible GaN-on-silicon technology with excellent D-mode MISHFET performance is realized. A low specific contact resistance R_c (0.35 Ω-mm) is achieved by Au-free process. MIS-HFET with a gate-drain distance (L_GD) of 15 μm exhibits a large breakdown voltage (BV) (980 V with grounded substrate) and a low specific on-resistance (R _ON,_sp) (1.45 mΩ-cm²). The importance of epitaxial quality in a key industrial qualification item: high temperature gate bias (HTGB) stress-induced voltage instability issue is figured out and a breakthrough by optimizing GaN epitaxial layer for improvement of MIS-HFET is demonstrated. A low V_th shift of the optimized MIS-HFET is achieved ~ 0.14V with qualification stress condition V_G of -15 V at ambient temperature of 150 oC for 128 hours.