Date of Award

3-11-2005

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

James C. Petrosky, PhD

Abstract

The effects of radiation on semiconductors are extremely important to the Department of Defense since the majority of the defense informational, navigational and communications systems are now satellite-based. Due to the high radiation tolerance of gallium nitride and a plethora of high temperature, high power and high frequency applications, the prospect that gallium nitride based devices will become key components in a multitude of military satellite-based systems is highly probable. AlGaN/GaN HEMTs were irradiated at low temperature (~80 K) by 0.45 – 0.8 MeV electrons up to fluences of 1×1015 e-/cm2. Following irradiation, low temperature capacitance-voltage measurements were recorded providing fluence-dependent measurements; additionally low-temperature post-irradiation capacitance-voltage measurements were recorded at twenty-four hour intervals up to 72 hours in order to investigate the room temperature annealing process. Using previously irradiated devices, the effects of a 9 month and 12 month room temperature anneal were also considered. Capacitance-voltage measurements indicate that low energy electron radiation results in an increase in the transistor channel drain current. These increases occur both at low and room temperature. The mechanism, clearly shown through capacitance-voltage measurements, causing the increase in drain current is an increase in the carrier concentration in the 2DEG. This result is due to donor electrons from a nitrogen vacancy in the gallium nitride. The devices begin to anneal immediately and show almost complete recovery after 72 hours.

AFIT Designator

AFIT-GNE-ENP-05-05

DTIC Accession Number

ADA437643

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