Investigation of Gate Leakage Current in Nitrogen-Irradiated AlGaN/GaN Heterostructures

Author

Rose E. May

Date of Award

3-11-2011

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

James C. Petrosky, PhD.

Abstract

Due to commercial and government interest in devices capable of functioning in high-power, high-frequency space applications, radiation tolerant AlGaN/GaN devices have been under study in recent years. Passivation of the AlGaN surface by (Si₃N₄) prevents electron trapping and enhances the 2DEG, but it also increases gate leakage currents, which can lead to device failure. This study sought information about current leakage mechanisms by introducing displacement damage close to the Si₃N₄/AlGaN interface. The effects of irradiation damage around the Si₃N₄/AlGaN interface on irradiation-induced leakage current were investigated for three thicknesses of a Si₃N₄ passivation layer in addition to an unpassivated sample. AlGaN/GaN samples were irradiated at room temperature with 15-50keV nitrogen ions. Hall measurements determined mobility and 2DEG carrier density. C-V measurements provided insight into charge location and effects of the band structure. Pre-irradiation measurements were compared to the irradiation results to determine the types and amounts of damage done in the devices. Post-irradiation C-V measurements showed greater than 50% decrease in capacitance and an average -3V shift in V_th which persisted in the passivated samples. Post-irradiation Hall measurements showed decreases in mobility for both passivated and unpassivated samples. Carrier concentration decreased for passivated samples but increased for the unpassivated sample.

AFIT Designator

AFIT-GNE-ENP-11-M14

DTIC Accession Number

ADA591628

Recommended Citation

May, Rose E., "Investigation of Gate Leakage Current in Nitrogen-Irradiated AlGaN/GaN Heterostructures" (2011). Theses and Dissertations. 1463.
https://scholar.afit.edu/etd/1463