Date of Award

3-2023

Document Type

Thesis

Degree Name

Master of Science in Nuclear Engineering

Department

Department of Engineering Physics

First Advisor

Christina L. Dugan, PhD

Abstract

The germanium tin band gap is responsive to wavelengths in the mid to near infrared spectrum; this shows promise in meeting the detection demands of the next generation infrared detectors. Recent developments in germanium tin (GeSn) alloy growth techniques have peaked the scientific community’s interest in GeSn based optoelectrical and detection devices. Detection materials made entirely of group IV elements are compatible with complementary metal-oxide semiconductor manufacturing techniques. Understanding the surface chemistry of this alloy is fundamental for solid state device design and must be analyzed to optimize device performance. Studies have shown that with the addition of tin, the indirect band gap energy of germanium transitions to a direct band gap. The band structures and oxidation states impact semiconductor device performance. This work interrogated the surface of GeSn alloys using x-ray photoelectron spectroscopy (XPS) to study the surface chemistry by measurement in both core and valence regions. The XPS valence band spectra were used to estimate the band gap energies. GeSn alloys with reported Sn concentrations of 7.5, 8.8, 12.5, and 19.3% were analyzed with observed band gap values of 0.57, 0.47, 0.34, and 0.35 eV respectively. The oxide percentages present within the Sn 3d and Ge 3p photoelectron features were calculated showing a varying percentage based on angle resolve XPS.

AFIT Designator

AFIT-ENP-MS-23-M-090

Comments

A 12-month embargo was observed.

Approved for public release. PA case number on file.

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