IEEE Journal of the Electron Devices Society (Jan 2019)

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

  • K. Ranjan,
  • S. Arulkumaran,
  • G. I. Ng,
  • A. Sandupatla

DOI
https://doi.org/10.1109/JEDS.2019.2947564
Journal volume & issue
Vol. 7
pp. 1264 – 1269

Abstract

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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.

Keywords