Date of Award

2017

Document Type

Open Access Thesis

Department

Electrical Engineering

Sub-Department

College of Engineering and Computing

First Advisor

Krishna C. Mandal

Abstract

Anisotropic wide-bandgap gallium selenide (GaSe) crystals were grown using high purity (7N) Ga and zone refined (ZR) Se precursor materials. The crystal growth was performed using a modified vertical Bridgman method (VBM) with a slow crystallization from the melt and with a pre-determined temperature profile. The structure, surface morphology, and the composition of the grown crystals were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive analysis by x-rays (EDAX), respectively. Optical absorption and transmission properties were characterized and optical bandgap was determined. Electrical resistivity has been determined using current-voltage (I V) measurements using van der Pauw geometry. Electrical contact properties have been measured with various metals of different work functions, and the optimum Schottky barrier properties have been evaluated. Metal-semiconductor-metal (MSM) devices were fabricated and evaluated for radiation detector applications. Pulse height spectra (PHS) measurements were carried out using a 241Am (59.6 keV) radiation source. Finally grown GaSe crystals were evaluated for THz sources and emission properties were determined. The results demonstrate that GaSe is a promising semiconductor for nuclear detection in Homeland security, nuclear non-proliferation, and nuclear power plants. The GaSe crystals also showed high potential as a THZ source that could be used for imaging of concealed weapons, explosives, illicit drugs, chemical warfare, and biological agents.

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