Performance and limitations of AlGaN/GaN HFETs grown on sapphire and SiC substrates

In this paper we report on the fabrication and performance of AlGaN/GaN HFETs grown on sapphire and SiC substrates. Due to the excellent material properties record extrinsic transconductance and current values were achieved, with promising RF power performance. We discuss in detail the performance limitations of the fabricated devices with respect to thermal effect, degradation and current transients.