Gate stacked dual-gate MISHEMT with 39 THz·V Johnson’s figure of merit for V-band applications

Abstract

In this investigation, extensive simulations were performed for an AlGaN/GaN Dual-Gate MISHEMT configuration using ATLAS TCAD to optimize the device design for high power switching applications. We conducted a simulation study for the breakdown characteristics of a Dual-Gate AlGaN/GaN (DG)-MISHEMT with different gate lengths as explained in this paper. The optimized device with 0.25\xa0µm gate length exhibits an breakdown voltage\u2009>\u2009700\xa0V and an cut-off frequency of 50\xa0GHz when gate2 (G2) is attached to the source and bias is applied at gate1 (G1). We studied the impact on a breakdown characteristics and the frequency performance of different dimensions such as distance between the two gates (L GG ), gate1-to-source distance (L G1S ) and gate1-to-drain distance (L G1D ). The optimized device design was further used to study the scattering-parameters for different gate combinations. Further improvement in breakdown voltage and Johnson’s figure of merit ( f T \u2009×\u2009V BR ) is achieved for the DG-MISHEMT with HfO 2 –Al 2 O 3 as gate insulator.