Investigation of Self-Heating Effect on DC and RF Performances in AlGaN/GaN HEMTs on CVD-Diamond

Abstract

Abstract-We have investigated the self-heating effect on DC and RF performances of identically fabricated AlGaN/GaN HEMTs on CVD-Diamond (GaN/Dia) and Si (GaN/Si) substrates. Self-heating induced device performances were extracted at different values drain bias voltage ( VD ) and dissipated DC power density ( PD ) in continuous wave (CW) operating condition. The effect of self-heating was observed much lesser in GaN/Dia HEMTs than GaN/Si HEMTs in terms of ID , IG , gm , fT and fmax reduction. Increased channel temperature caused by joule heating at high PD reduces the 2-DEG carrier mobility in the channel of the device. This behaviour was also confirmed by TCAD simulation which showed 3.9-times lower rising rate of maximum channel temperature and lowers thermal resistance ( Rth ) in GaN/Dia HEMTs than GaN/Si HEMTs. Small signal measurements and equivalent circuit parameter extraction were done to analyze the variation in performance of the devices. Our investigation reveals that the GaN/Dia HEMT is a promising candidate for high power density CW operation without significant reduction in electrical performance in a large drain bias range.