Thesis (M. Phil.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 67-72).

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 142-149). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--Virginia Commonwealth University, 2008. / Prepared for: Dept. of Electrical Engineering. Title from thesis description page. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 29-30). Also available in electronic version.

Thesis (M.S.)--Oregon Graduate Center, 1987.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

While photovoltaic (PV) manufacturing is on track to provide a substantial portion of world electricity generation, the growth of the industry is likely to be lower than desired to meet targets designed to mitigate climate change. Many different PV technologies have been developed, but PV modules based on Si are the dominant technology due to its low cost and relatively high energy conversion efficiencies. PV modules based on III-V materials are primarily used for aerospace applications due to their high cost and record-setting efficiencies. Traditional manufacturing techniques for III-V PV require expensive precursors, and have high capital costs and low throughput. Close-spaced vapor transport (CSVT) is an alternative technique for deposition of III-V materials that was invented in the 1960s but has not been fully developed for the production of PV devices. This work describes progress towards high efficiency solid-state GaAs solar cells produced by CSVT. Previous results have demonstrated good electronic quality of CSVT GaAs using photoelectrochemical cells, but such devices have not been demonstrated to be commercially practical. This work investigates the potential of CSVT to produce high-efficiency III-V PV by fabricating and characterizing GaAs films and simple homojunction solar cells. Chapter I describes the motivation and state of III-V PV research, and establishes basic device physics background. Chapter II gives details of film growth and device design and fabrication. Chapter III gives an overview of the film and device characterization methods employed. Chapter IV explores the primary limitations in the efficiency of the homojunction solar cells fabricated for this study and discusses some practical concerns in translating the technique to a manufacturing environment. Chapter V explores the electronically-active defects in both $n$-type films and in $p$-type absorbers of solar cells, which would be likely to limit the efficiency of devices optimized considering the results presented in Chapter IV. Chapter VI discusses some of the possible future directions for applying CSVT to more advanced device structures which are more commercially relevant, including the growth on alternative substrates and growth of ternary materials for passivating layers or multijunction cells. This dissertation includes previously published and unpublished co-authored material.

No description available.

In this work, the growth and characterisation of the chalcopyrite semiconductor CuGaS2 is presented. The purpose of this study is to gain a better understanding of the defect chemistry of this class of materials through a systematic study relating the structural and optical properties to the composition of thin films grown by metalorganic vapour phase epitaxy. Details associated with the optimisation of the growth process are presented in a format relating the changes in the composition and morphology to variations in the growth process. The structural properties of thin films grown on GaAs(001) substrates are described. A dominance of polycrystalline growth is found to occur for Cu-rich material, whereas near-stoichiometric to Ga-rich material is typified by epitaxial growth. Secondary phases are identified by X-ray diffractometry and Raman spectroscopy for severely non-stoichiometric material. In some cases, the formation of the cubic zincblende and CuPt polytype of CuGaS2 are identified by transmission electron microscopy. It will be shown that changes in the Cu/Ga ratio of the solid strongly influence the photoluminescence response of the layers. Weak excitonic luminescence is observed for both slightly Ga-rich and Cu-rich material. Near stoichiometric layers exhibit luminescence centered at ~2.4 eV. Cu-rich layers are dominated by a line occurring at ~2.1 eV, whereas a different line at ~2.25 eV dominates for Ga-rich layers. A clear picture emerges of the radiative mechanisms dominating for Cu-rich and Ga-rich layers.