In this study, advanced techniques in the synthesis of germanium nanoparticles have been investigated. Based on physical and chemical production methods, including stain etching, liquid-phase pulsed laser ablation, sol-gel synthesis and two benchtop colloidal synthesis techniques, germanium nanoparticles with various surface terminations were formed. Out of those, colloidal synthesis by benchtop chemistry (named CS1) were found to be the most promising synthesis route in terms of yield and stability of the as-prepared Ge qdots and its luminescence with almost no oxides present. For the characterisation of Ge nanoparticles, Raman spectroscopy, Photoluminescence (PL) spectroscopy, Transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX) and selective area electron diffraction (SAED) techniques were utilised before conducting X-ray absorption spectroscopy (XAS) measurements. The structure and morphology of Ge quantum dots formed using colloidal synthesis routes were found to fit best to the model of a nanocrystalline core surrounded by disordered Ge layers. Optically-detected X-ray absorption studies have enabled us to establish a direct link between nanoparticles structure and the source of the luminescence. The most important outcome of this study is that it provides a direct experimental route linking synthesis conditions and properties of nanosized Ge quantum dots. Furthermore, using annealing, we can control surface termination even further, as well as change particle size and possibly produce metastable phases.

Cheuk Wai So. / "June 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Lui Ka Man Raymond. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 190-202). / by Lui Ka Man Raymond. / Acknowledgements / Abstract / Table of contents --- p.i / Chapter Chapter 1 --- Introduction / Chapter 1.1) --- General overview --- p.1 / Chapter 1.2) --- The present study --- p.4 / Chapter Chapter 2 --- Theory / Chapter 2.1) --- Introduction --- p.8 / Chapter 2.2) --- Energy transfer from an incoherent radiation source --- p.9 / Chapter 2.3) --- Interaction between photons and solid --- p.11 / Chapter 2.4) --- Probability of a direct transition of amorphous germanium to liquid germanium --- p.12 / Chapter 2.5) --- Crystallization in the supercooled melts and interface stability of the crystallizing front --- p.20 / Chapter A) --- Homogeneous nucleation --- p.21 / Chapter B) --- Heterogeneous nucleation --- p.24 / Chapter C) --- Interfacial stability of the crystallizing front --- p.25 / Chapter Chapter 3 --- Sample preparation / Chapter 3.1) --- Introduction --- p.36 / Chapter 3.2) --- The sample preparation system --- p.36 / Chapter A) --- General description --- p.36 / Chapter B) --- The electron beam source and other components --- p.37 / Chapter C) --- The thermal pulse furnace (TPF) --- p.38 / Chapter 3.3) --- The substrates --- p.41 / Chapter 3.4) --- Sample preparations --- p.42 / Chapter Chapter 4 --- Dendritic crystallization of amorphous germanium on amorphous substrate / Chapter 4.1) --- Introduction --- p.47 / Chapter 4.2) --- Sample preparation and experimental methods --- p.48 / Chapter A) --- Sample preparation --- p.48 / Chapter B) --- Characterization methods --- p.50 / Chapter 4.3) --- Experimental results --- p.54 / Chapter 4.4) --- Discussions --- p.58 / Chapter A) --- Existence of a supercooled semiconductive liquid phase --- p.58 / Chapter B) --- Suppression of nucleation in the supercooled liquid --- p.61 / Chapter C) --- The effect of substrate width on the confinement of <110> crystal axes --- p.63 / Chapter D) --- The effect of annealing ambient --- p.63 / Chapter 4.5) --- Conclusions --- p.65 / Chapter Chapter 5 --- Transport properties of dendritic Ge films / Chapter 5.1) --- Introduction --- p.93 / Chapter 5.2) --- Theory --- p.93 / Chapter A) --- Expression of electrical drift mobility by the relaxation time approximation --- p.94 / Chapter B) --- Electrical drift mobility resulting from ionized impurity scattering --- p.98 / Chapter 5.3) --- Experimental methods --- p.102 / Chapter A) --- Sample annealing --- p.102 / Chapter B) --- Temperature-dependent electrical conductivity measurements (303 K - 523 K) --- p.102 / Chapter C) --- Temperature-dependent Hall mobility measurements (20 K - 300 K) --- p.103 / Chapter 5.4) --- Experimental results --- p.105 / Chapter A) --- Conductivity in the high temperature range K - 303 K --- p.105 / Chapter B) --- Sheet conductance in the temperature range 300K - 20 K --- p.105 / Chapter C) --- Hall mobility in the temperature range 300K to 20 K --- p.107 / Chapter 5.5) --- Discussions --- p.108 / Chapter A) --- Temperature dependence of electical conductivity --- p.108 / Chapter B) --- Temperature-dependent Hall mobility measurements --- p.111 / Chapter 5.6) --- Conclusions --- p.115 / Chapter Chapter 6 --- Crystallization of amorphous germanium film on (001) GaAs wafers / Chapter 6.1) --- Introduction --- p.131 / Chapter A) --- General review --- p.131 / Chapter B) --- The present study --- p.132 / Chapter 6.2) --- Sample preparation and experimental methods --- p.134 / Chapter A) --- Sample preparation --- p.134 / Chapter B) --- Characterization methods --- p.135 / Chapter 6.3) --- Experimental results --- p.143 / Chapter A) --- Epitaxial regrowth of a-Ge films on semi-insulating (001) GaAs --- p.144 / Chapter B) --- Influence of the substrate and the initial thickness of a-Ge film on the process of crystallization --- p.146 / Chapter C) --- Results from electron spectroscopy and EDX dot-map --- p.148 / Chapter D) --- The electrical property of the Ge/GaAs heterojunction --- p.150 / Chapter 6.4) --- Discussions --- p.150 / Chapter A) --- Substrate dependence --- p.150 / Chapter B) --- Sample thickness dependence --- p.153 / Chapter C) --- Regrowth mechanism --- p.154 / Chapter 6.5) --- Conclusions --- p.156 / Chapter Chapter 7 --- Conclusions and suggestions for further studies / Chapter 7.1) --- Conclusions --- p.183 / Chapter A) --- On amorphous substrate [Corning 7059 glass] --- p.183 / Chapter B) --- On crystalline substrate [GaAs (001) wafer] --- p.185 / Chapter 7.2) --- Suggestions for further studies --- p.186 / Chapter A) --- Synthesis of Ge/GaAs heterojunction with abrupt interface --- p.186 / Chapter B) --- Applying the thermal pulse annealing method to other systems --- p.186 / Chapter C) --- Studying the size and shape-dependence of Raman spectrum by using sample with highly uniform grain size and well-defined geometry --- p.187 / Appendix A --- p.188 / References --- p.190

Graduation date: 1999

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references (leaves 163-173). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

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