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

• Main Authors: K. Ranjan, S. Arulkumaran, G. I. Ng, A. Sandupatla
• Format: Article
• Language: English
• Published: IEEE 2019-01-01
• Series: IEEE Journal of the Electron Devices Society
• Subjects: AlGaN/GaN; HEMT; CVD-diamond; self-heating; DC; RF and TCAD
• Online Access: https://ieeexplore.ieee.org/document/8869814/

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 I_D, I_G, g_m, f_T and f_max 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.