Effect of different layer structures on the RF performance of GaN HEMT devices

Abstract

In this paper we have studied AlGaN/GaN high electron mobility transistor devices with three different buffer layer structures and their effect on the RF performance of the devices. Detailed DC and pulsed IV measurements were carried out to investigate the effect of bulk traps on the performance of the devices. Activation energy of buffer traps is also investigated by low frequency S-parameter measurements of the devices at variable temperature. The effect of buffer structure and quality of buffer on RF gain has been observed for the devices. Using the S-parameters, the equivalent circuit model parameters of the devices were also extracted. All the characterizations revealed that the presence of low C-doped buffer shows less vulnerability towards traps and produces better RF performance. It was also observed that the device with only low C-doped thin buffer reproduces better RF characteristics.