Yi-Hsien Chang

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.

GaN cascode performance optimization for high efficient power applications

GaN Cascode performance optimization for high efficient power applications is presented in this paper. Analytical equations of Cascode capacitance network (Ciss, Coss, Cgd) is demonstrated and the equations accuracy is verified through experimental measurement. Analysis shows that Cascode Cgd is determined by HV D-MISFETs Cds, LV Si FETs Cgd/Coss ratio, and extra zener diode capacitance. With low intrinsic capacitance HV D-MISFETs [1-2], proper LV Si FETs selection, and extra zener diode protection, optimization for Cascode switching figure-of-merit (FOM, Ron x Qgd) is well demonstrated. 8.8X lower switching figure-of-merit than commercial best-in-class Si SJ FETs [3] is achieved, double pulse test (DPT) and hard switching PFC system verification result all indicate that GaN Cascode is the promising solution and ready for next generation energy systems.