Date of Graduation

8-2025

Document Type

Thesis

Degree Level

Graduate

Department

Materials Science & Engineering

Advisor/Mentor

Churchill, Hugh

Committee Member

Salamo, Gregory

Second Committee Member

Paillard, Charles

Third Committee Member

Kohanek, Julia

Fourth Committee Member

Shui-Qing Yu

Keywords

2D Materials; Gallium Selenide; van der Waals Epitaxy

Abstract

Gallium selenide (GaSe) is a thin-film semiconducting material with promising optoelectronic properties, including a tunable bandgap, high photosensitivity, and atomic-layer scalability. These characteristics make it suitable for devices such as photodiodes, FETs, MOSFETs, Hall effect sensors, and p–n diodes. In this study, GaSe thin films were grown on SiO2 and Si(111)-7×7 substrates using molecular beam epitaxy (MBE) to compare growth behavior across different substrates. The films were characterized using Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectroscopy, and reflection high-energy electron diffraction (RHEED). RHEED confirmed the 7×7 reconstruction of the Si(111) surface and the amorphous nature of SiO2. Post-growth RHEED patterns, along with AFM analysis, revealed distinct surface morphologies. PL spectroscopy identified bandgap-related emission, while XRD and Raman spectroscopy confirmed the crystallinity and polytype structure of the films. The results demonstrate that the choice of substrate significantly influences the structural, electrical, and optical properties of GaSe thin films, with implications for integration into silicon-based optoelectronic devices.

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