Light-Triggered, Enhancement-Mode AlInN/GaN HEMTs With Sub-Microsecond Switching Times

Light-triggered, AlInN/GaN high-electron-mobility transistors (HEMTs) are presented. Selective thermal oxidation of the AlInN barrier between the source and drain depletes the AlInN/GaN 2-dimensional electron gas, enabling enhancement mode operation and light-triggering capability. A commercially available 375 nm laser diode is focused on the bare (no metal) oxidized gate, and despite being below bandgap, it triggers the HEMT into the on-state. The HEMTs have a peak saturation current of ~60 mA/mm, switch at 100 kHz, exhibit sub-microsecond switching times which are faster than other GaN-based switching devices, and are limited by the laser power supply.