by Tsoi Hing Lun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 98-102). / Abstracts in English and Chinese. / Acknowledgement --- p.i / 摘要 --- p.ii / Abstract --- p.iii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- General review --- p.1 / Chapter 1.2 --- Our work --- p.4 / Chapter Chapter 2 --- Experimental setup and procedures / Chapter 2.1 --- Sample preparation --- p.6 / Chapter 2.1.1 --- ZnSe heterostructure --- p.6 / Chapter 2.1.2 --- Quantum dot --- p.7 / Chapter 2.2 --- Common aspects of Raman scattering --- p.8 / Chapter 2.3 --- General studies --- p.11 / Chapter 2.3.1 --- Excitation power density dependent studies --- p.11 / Chapter 2.3.2 --- Angular dependent studies --- p.12 / Chapter 2.3.3 --- Excitation energy dependent studies --- p.14 / Chapter 2.4 --- Peripheral measurements --- p.16 / Chapter 2.4.1 --- Spectral calibration --- p.16 / Chapter 2.4.2 --- Alignment and system stability checks --- p.18 / Chapter 2.5 --- The method of measuring the Raman scattering efficiency --- p.19 / Chapter Chapter 3 --- Band Bending at the interface of ZnSe/GaAs / Chapter 3.1 --- Results and discussions --- p.27 / Chapter Chapter 4 --- Characteristics of QD phonons / Chapter 4.1 --- Angular dependent studies --- p.38 / Chapter 4.2 --- Excitation energy dependent studies --- p.60 / Chapter 4.3 --- The nature of the QD phonons --- p.64 / Chapter 4.4 --- The measurement of the Raman scattering efficiency of QDs --- p.67 / Conclusions --- p.75 / Future work --- p.73 / Appendix1 --- p.79 / Appendix2 --- p.82 / Appendix3 --- p.86 / Appendix4 --- p.88 / Appendix5 --- p.95 / References --- p.93

No description available.

by Chen Dihu. / "November 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 160-173). / 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.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 159-164).

We mainly studied the characterization of GaN/AlGaN heterostructures which were grown by molecular beam epitaxy. For reduced lattice mismatch, we inserted AlN as buffer layer. We varied the parameters of buffer layer, such as the ratio of nitrogen and aluminum and the thickness. By the analysis of X-ray diffraction, we could determine the state of mismatch. For the thickness of buffer layer, lattice mismatch is most serious at 20 minute growth. Under the observation of field emission scan electron microscopy and reflection high energy electron diffraction, we found N/Al=40 is N-face and N/Al=26 is Ga-face. For the thickness of buffer layer, the samples of 1-minute and 5-minute growth had the optimal Ga-face. For the investigation of photoluminescence, we could obtain the energy gap of AlGaN is 3.42ev. Furthermore, the doping silicon was used to vary carrier concentration, and we could show that a good Hall mobility was achieved at the doping temperature 1250¢J. We also could show good Hall mobility at 1 minute growth and 5 minute growth (N/Al=26). We tried to find the best parameters for the growth of GaN/AlGaN heterostructures.

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2004. / May, Gary, Committee Chair; Doolittle, William, Committee Member; Brown, April, Committee Member; Wang, Zhong Lin, Committee Member; Ralph, Stephen, Committee Member. Includes bibliography.

Colloidally synthesized silicon (Si) and germanium (Ge) were explored as high capacity anode materials in lithium ion batteries. a-Si:H particles were synthesized through the thermal decomposition of trisilane in supercritical n-hexane. Precise control over particle size and hydrogen content was demonstrated. Particles ranged in size from 240-1500 nm with hydrogen contents from 10-60 atomic%. Particles with low hydrogen content had some degree of local ordering and were easily crystallized during Raman spectroscopy. The as-synthesized particles did not perform well as an anode material due to low conductivity. Increasing surface conductivity led to enhanced lithiation potential. Cu nanoparticles were deposited on the surface of the a-Si:H particles through a hydrogen facilitated reduction of Cu salts. The resulting Cu coated particles had a lithiation capacity seven times that of pristine a-Si:H particles. Monophenylsilane (MPS) grown Si nanowire paper was annealed under forming gas to reduce a polyphenylsilane shell into conductive carbon. The resulting paper required no binder or carbon additive and achieved capacities of 804 mA h/g vs 8 mA h/g for unannealed wires. Si and Ge heterostructures were explored to take advantage of the higher inherent conductivity of Ge. Ge nanowires were successfully coated with a-Si by thermal decomposition of trisilane on their surface, forming Ge@a-Si core shell structures. The capacity increased with increasing Si loading. The peak lithiation capacity was 1850 mA h/g after 20 cycles – higher than the theoretical capacity of pure Ge. MPS additives created a thin amorphous shell on the wire surfaces. By incubating the wires after MPS addition the shell was partially reduced, conductivity increased, and a 75% increase in lithiation capacity was observed for the nanowire paper. The syntheses of Bi and Au nanoparticles were also explored. Highly monodisperse Bi nanocrystals were produced with size control from 6-18 nm. The Bi was utilized as seeds for the SLS synthesis of Ge nanorods and copper indium diselenide (CuInSe2) nanowires. Sub 2 nm Au nanocrystals were synthesized. A SQUID magnetometer probed their magnetic behavior. Though bulk Au is diamagnetic, the Au particles were paramagnetic. Magnetic susceptibility increased with decreasing particle diameter. / text

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The conduction band of InAs lies lower in energy than the GaSb valence band. In order to preserve continuity of the Fermi level across the interface, charge transfer takes place resulting in a confined quasi two dimensional electron gas (2DEG) in the In As and a confined quasi two dimensional hole gas (2DHG) in the GaSb. This is the first detailed study into vertical transport in an n-InAs/p-GaSb single heterojunction (SHET). Application of a forward bias (InAs negative with respect to GaSb) increases the 2DEG and 2DHG concentrations and, therefore, their confinement energies. Eventually a critical bias is reached where the electron confinement energy moves above the hole confinement energy (the theoretical voltage induced semimetallsemiconductor transition V_c). Any subsequent increase in voltage is expected to result in a current decrease, and a region of negative differential resistance (NDR) should occur. The SHET can be grown with two distinct interface types, 'InSb-like' and 'GaAslike'. This study shows for the first time that the SHET vertical transport characteristic is very dependent upon this interface monolayer. For example, the temperature dependence of the I/V trace in a SHET with a 'GaAs-like' interface is found to be weak, with similar current peak to valley ratios (PVR) at 300 and 77K. The 'InSblike' SHET, however has a PVR that is very close to 1 at 300K, rising above 2 at 77K. Hydrostatic pressure is used to alter reversibly the InAs conduction/GaSb valence band overlap Δ. Vertical transport measurements taken at pressure confirm that Δ reduces at the same rate for both interface types and that it is larger for the 'InSb-like' interface. Experimental I/V traces at various pressures are compared with the corresponding results from self-consistent band profile calculations. The subsequent discoveries are that NDR occurs after V_c for both interfaces, and that each interface supports a different conduction mechanism - with the 'GaAs-like' interface exhibiting NDR when the band overlap is calculated to be ~ -100 meV. Magnetic fields have been applied both perpendicular and parallel to the SHET interface. The perpendicular field results provide additional evidence that the conduction process must be different at both interfaces and that NDR occurs after V_c. Parallel field I/V traces reveal an entirely different response for the two interface types.

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