70 mΩ/600 V normally-off GaN transistors on SiC and Si substrates

The static and dynamic electrical performance of normally-off p-GaN gate AlGaN/GaN HFETs, manufactured on SiC and on Si substrates are compared. By implementing a p-type GaN gate, normally-off operation with 1 V threshold voltage has been realized for 70 mΩ / 600 V transistors on both substrates. The GaN-on-SiC devices out-perform Si-based superjunction MOSFETs in terms of gate charge and switching energy and feature a low area-specific on-state resistance, also when considering the full chip area. The higher thermal impedance of the GaN-on-Si devices is reflected in a reduced maximum drain current for pulse lengths > 1 μs. However, no significant thermal effect was found for lower pulse powers as targeted for efficient power switching.