This work explores the synthesis and characterization of the metastable alloys Sn1-xCaxCh (Ch= S, Se) and nitride compounds Zn-W-Mo-N, which have recently been predicted by theorists. Single phase thin films of Sn1-xCaxS are prepared by pulsed laser deposition and radio-frequency magnetron sputtering and of Sn1-xCaxSe are prepared by pulsed laser...
Several topics are presented in this dissertation, each of which has applications to solar cells and photodetectors. First, we discuss the growth of Cu10Te4S13, copper tellurium tetrahedrite. This material has interesting optical properties; it has a large joint density of states at the conduction band maximum and valence band minimum,...
Phosphate and peroxide stabilize new oxo-hydroxo niobium clusters in water at low pH. The clusters open a new chapter in aqueous niobium chemistry under acidic conditions. The clusters also produce atomically smooth, amorphous niobium oxide phosphate (NbPOx) thin films. Reaction pathways from cluster solutions to amorphous niobium oxide phosphate solids...
The trend towards higher resolution, faster refresh rate active-matrix liquid-crystal displays (AMLCDs) as well as the emergence of active-matrix organic light-emitting diode (AMOLED) displays is driving the demand for amorphous oxide semiconductor thin-film transistors (AOS TFTs) with higher mobility. A physics-based model for carrier transport in an amorphous semiconductor is...
CIGS and CdTe based commercial thin-film solar cells (TFSCs) require an absorber thickness greater than 2 µm and 4 µm, respectively, to adequately absorb the solar spectrum. To efficiently extract photoexcited electrons, these TFSCs require relatively defect-free absorbers with high-minority carrier mobility (> 100 cm2V−1s−1) and long lifetime (> 10...
Chemistry of preparing dense film from solution deposition is explored with several cases in this thesis. Surface dense structure, conversion at melting point, and ion exchange in aqueous solution are the main topics covered here for the thin films of aluminum oxide phosphate and tin dioxide. Thin film density, optical...
Copper antimony sulfide (CAS) is a ternary material that is of research interest for thin film photovoltaic applications due to its high absorption coefficient and tunable bandgap. The material is also ideal for sustainable manufacturing due the constituent elements being earth-abundant and less toxic than solar cell absorbers like gallium...
In this work we consider two multiscale applications with tremendous computational complexity at the lower scale. First, we examine a model for charge transport in semicon- ductor structures with heterojunction interfaces. Due to the complex physical phenomena at the interface, the model at the design scale is unable to adequately...
An experimental apparatus is modified to allow measurements of the Seebeck coefficient and resistivity to be taken simultaneously. This apparatus is designed for bulk and thin film samples between temperatures of 10 K and 300 K. The apparatus is constructed such that these simultaneous measurements do not interfere with each...
The subject of this PhD thesis is part of a research domain of great present interest in new semiconductor materials for photovoltaic and thermoelectric applications. This domain contains the elaboration and the study of both Cu-based chalcogenides bulk and thin-film samples, driven by materials design principles.
One of the most...