Experimental Characterization of the Thermal Time Constants of GaN HEMTs Via Micro-Raman Thermometry
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Experimental characterization of thermal time constants manuscript 02162017.pdf
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Main article
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Author(s)
Bagnall, Kevin Robert
Saadat, Omair Irfan
Jayanta Joglekar, Sameer
Palacios, Tomas
Wang, Evelyn
Date Issued
March 2017
Journal
IEEE Transactions on Electron Devices
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Citation
Bagnall, Kevin R.; Saadat, Omair I.; Joglekar, Sameer et al. “Experimental Characterization of the Thermal Time Constants of GaN HEMTs Via Micro-Raman Thermometry.” IEEE Transactions on Electron Devices 64, 5 (May 2017): 2121–2128 © Institute of Electrical and Electronics Engineers (IEEE)
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Author's final manuscript
Abstract
Gallium nitride (GaN) high-electron mobility transistors (HEMTs) are a key technology for realizing next generation high-power RF amplifiers and high-efficiency power converters. However, elevated channel temperatures due to self-heating often severely limit their power handling capability. Although the steady-state thermal behavior of GaN HEMTs has been studied extensively, significantly fewer studies have considered their transient thermal response. In this paper, we report a methodology for measuring the transient temperature rise and thermal time constant spectrum of GaN HEMTs via time-resolved micro-Raman thermometry with a temporal resolution of 30 ns. We measured a broad spectrum of time constants from ≈130 ns to ≈3.2 ms that contribute to the temperature rise of an ungated GaN-on-SiC HEMT due to aggressive, multidimensional heat spreading in the die and die-attach. Our findings confirm previous theoretical analysis showing that one or two thermal time constants cannot adequately describe the transient temperature rise and that the temperature reaches steady-state at 16L²/π²α, where L and α are the thickness and thermal diffusivity of the substrate. This paper provides a practical methodology for validating transient thermal models of GaN HEMTs and for obtaining experimental values of the thermal resistances and capacitances for compact electrothermal modeling.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Microsystems Technology Laboratories
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DOI of Published Version
https://doi.org/10.1109/TED.2017.2679978
