Author

Kyler Kooi

Author ORCID Identifier

https://orcid.org/0000-0003-1436-2021

Document Type

Dissertation

Date of Award

2024

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

First Advisor

Jing Liu

Abstract

High purity germanium is a popular radiation detecting medium due to the excellent energy resolution that is achieved. The unique semiconducting properties of germanium allow a small amount of energy to create free charges in the germanium, which are then collected as a signal. Germanium detectors also have good spatial resolution. The shape of the signal can be used to identify the location of energy deposition in the crystal. Both of these properties make germanium detectors a popular choice in many felds, including security, medical, astrophysics, and particle physics. The properties of a germanium crystal should be well understood and measured to get the best results from the detector. The two most important properties to measure are the carrier concentration and free charge mobility in the crystal. The carrier concentration is a measure of the density of free charges that are given by impurities present in the crystal. This determines the electric feld in the crystal when a voltage is applied. The free charge mobility is a measure of the relationship between electric feld strength and the charge carrier velocities. This determines the shape of the signal produced. Mobility has been measured in germanium crystals using a variety of techniques, but the measurement setups are complicated and outdated. A new method of measuring mobility is presented in this dissertation that is intended to be simple and reproducible for anyone wishing to characterize a germanium crystal wafer.

Subject Categories

Condensed Matter Physics | Physics

Keywords

Germanium, HPGe Detectors, Mobility, Radiation Detection

Number of Pages

158

Publisher

University of South Dakota

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