Physics of GaN-based Power Field Effect Transistors

Abstract

Unique properties of GaN/AlN/InN heterostructures make them superior for high power applications. The key issues in the device designs are achieving normally-off operation, controlling the electric field distribution in the device channel to prevent breakdown, eliminating or reducing non-ideal effects causing reliability issues, and providing for efficient heat dissipation. High electric fields at the gate edges lead to an additional strain and hot electron effects causing the current collapse and gate lag. Quantum well designs (e.g. incorporating an InGaN or GaN quantum well between the wide band gap AlGaN barrier layer and GaN or AlGaN buffer) might control the wave function penetration and the real space transfer and increase the breakdown voltage. Insulated gate heterostructure HFETs (MOSHFETs) demonstrated superior performance and reliability. Field plates, recessed and double recessed gates, drain field controlled electrodes have been used to control current collapse and improve device reliability. An emerging approach is Frequency Configurable Electronics that enables better electric field uniformity.