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Title page for ETD etd-06272013-203146

Type of Document Master's Thesis
Author Chen, Jin
Author's Email Address jin.chen.1@vanderbilt.edu
URN etd-06272013-203146
Title Radiation response and reliability of AlGaN/GaN HEMTS
Degree Master of Science
Department Electrical Engineering
Advisory Committee
Advisor Name Title
Dan M. Fleetwood Committee Member
Ronald D. Schrimpf Committee Member
  • reliability
  • radiation
  • HEMT
  • 1/f noise
  • AlGaN/GaN
Date of Defense 2013-06-21
Availability unrestricted
Gallium Nitride (GaN)-based devices are used in space-based high power, high frequency applications due to high breakdown voltage and high carrier mobility and the large bandgap of GaN. The radiation effects and hot carrier degradation of AlGaN/GaN HEMTs are investigated in this work. Low frequency noise measurements are employed to help understand the nature of the defects that are responsible for the reliability and radiation response of GaN HEMT devices. The HEMT devices show excellent radiation hardness to 10-keV X-ray irradiation but 1.8 MeV proton irradiation results in a positive shift in the threshold voltage and reduction in current and transconductance. The temperature-dependent noise spectra show changes in defect distributions, with activation energy barriers of 0.2 eV, 0.6 eV and 0.9 eV. Density functional theory (DFT) calculations suggest that these energy levels are related to the dehydrogenation of ON-H defects. The noise spectra after hot carrier effects show similar features as those after proton exposure, strongly suggesting that dehydrogenation of ON DX centers takes place during the proton irradiation. The threshold voltage shift is negative after hot carrier stress, suggesting that other defects dominate the process that are out of the range of temperature-dependent noise measurement.
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