Degree Type

Thesis

Date of Award

2019

Degree Name

Master of Science

Department

Chemical and Biological Engineering

Major

Chemical and Biological Engineering

First Advisor

Matthew Panthani

Abstract

Due to the size-tunable properties and their potential application in many areas, nanocrystals (NCs) have been the focus of research over the past several decades. Among them, germanium (Ge) NCs are promising candidates for many optical applications such as LEDs and integrated photonics. In this thesis, we report the solid-state synthesis of Ge NCs at the temperature of 325 °C of higher as well as colloidal synthesis of Ge NCs at room temperature. For the solid-state synthesis, we use GeCl2 · dioxane as the precursor and performed hydrolysis to get germania (GeOX) glass, which was then thermally annealed at elevated temperatures. The formation of Ge NCs were confirmed by X-ray diffraction, transmission electron microscopy and Raman microscopy. X-ray photoelectron spectroscopy and Raman microscopy indicate the decomposition of germania glass and formation of small Ge NCs starts at 250 °C or lower. We demonstrate the germania glass has residual chlorine, which is speculated to be the reason for the formation of Ge NCs at relatively low temperature. The obtained Ge NCs were passivated with organic ligand via hydrogermylation to increase stability against oxidation and dispersibility. For the colloidal synthesis, germanium halide is used as precursor and trisilane is used as reducing agent. The reaction takes place at room temperature. Transmission electron microscopy, selected area electron diffraction and Raman microscopy confirm the presence of Ge NCs. This thesis serves to provide simple synthesis methods for Ge NCs that can be utilized in large-scale synthesis, as well as opens avenues for other potential research projects focusing on low temperature synthesis of NCs.

Copyright Owner

Yujie Wang

Language

en

File Format

application/pdf

File Size

81 pages

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