CMOS compatible GaN-on-Si HEMT technology for RF applications: analysis of substrate losses and non-linearities

Abstract

GaN-on-Si HEMTs are one of the leading technology options for 5G and beyond frond-end-modules. Substrate RF losses and harmonic distortion degrade performance of both active as well as passive devices for power amplifier and switch applications. In this paper, we report on the substrate RF loss and linearity performance of GaN-on-Si technology. It is shown that coplanar waveguides on GaN-on-high resistivity (3-6 k Omega.cm) CZ-Si wafers can achieve 2nd harmonic levels similar to-85 dBm (on a 2 mm long CPW line at P-out similar to 15 dBm) with effective resistivity p(eff) similar to 1 k Omega.cm. The impact of HEMT fabrication process and epitaxy on RF losses and distortion is studied and relationship between losses and distortion is discussed.