Advances in III-V transistors (HEMTs and HBTs) for mm-wave applications

Abstract

This paper reveals state-of-the-art performance capabilities and projections for the AlGaN/GaN-HEMT and AlGaN/GaN-HBT devices for mm-wave applications. Wide band gap, appropriate doping impurities, and strong atomic bonds make these III-V nitride materials most attractive for microwave devices. Research studies performed by the author indicate that the nitride-based GaN-HEMTs and -HBTs when fabricated on silicon carbide substrate are capable of providing highest power density and power-added efficiency (PAE) at mm-wave frequencies. Deployment of a group III-V material with wide gap band (3.49 eV) and silicon carbide (6H-SiC) substrate with high room-temperature thermal conductivity close to 4.5 W/cm./spl deg/C is necessary for the development of high-power, high-efficiency GaN-HEMT and -HBT devices operating at mm-wave frequencies. Device reliability under high operating temperatures is strictly dependent on the thermal conductivity of the GaN film and substrate used. Note the operating voltages of GaN devices are five to ten times of those for GaAs devices.