Temperature Dependent Current-Voltage Measurements of Neutron Irradiated Al_0.27Ga_0.73N/GaN Modulation Doped Field Effect Transistors

Author

Troy A. Uhlman

Date of Award

3-2005

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

James C. Petrosky, PhD

Abstract

In this research, the first ever neutron irradiation study of AlGaN/GaN MODFETs was conducted. Devices irradiated to a total 1 MeV Eq (Si) neutron fluence of 1.2x10¹⁶ n/sq cm demonstrated the temperature dependence of irradiation and annealing. Devices irradiated at 80 K exhibited significant persistent electrical degradation at only 5.4 rad (Si), whereas those irradiated at elevated temperatures exhibit transient increases in gate and drain current up to 400 krad (Si). I-V measurements indicate substantial radiation-induced increased gate and drain currents occur only at low-temperature irradiations. The introduction of a high-density of donor defects is hypothesized as the primary cause of both increased values. Irradiating at temperatures > 300 K effectively reduces total accumulated dose effects even at 400 krad(Si). Further analysis of the Schottky contacts has determined that the devices are field-emission and defect-assisted tunneling dominated at all temperatures. The Schottky diode parameters were extracted using a novel six-parameter fitting routine. To the authors knowledge this is the first application of such theory on AlGaN/GaN MODFETs.

AFIT Designator

AFIT-GNE-ENP-05M-16

DTIC Accession Number

ADA434221

Recommended Citation

Uhlman, Troy A., "Temperature Dependent Current-Voltage Measurements of Neutron Irradiated Al_0.27Ga_0.73N/GaN Modulation Doped Field Effect Transistors" (2005). Theses and Dissertations. 3745.
https://scholar.afit.edu/etd/3745