Zheng Hui Lim

ORCID Identifier(s)


Graduation Semester and Year




Document Type


Degree Name

Doctor of Philosophy in Physics and Applied Physics



First Advisor

Joseph H Ngai


Energy harvesting, sensing, and computing technologies utilizing conventional semiconductors have seen a plateau in their advancement for future applications. In order to address these issues, alternate materials are needed to improve present technologies. In my research, I proposed here that complex oxides can serve as potential candidate materials due to their properties. Single crystalline SrZrO3 thin film can be a potential candidate as dielectric material for Ge-based metal-oxide-semiconductor technologies. I present here a structural and electrical characterization of SrZrO3 thin film grown epitaxially on Ge (001) substrate with oxide molecular beam epitaxy. X-ray photoemission spectroscopy has shown that SrZrO3 thin film has a large conduction band and valence band offset with respect to Ge. Moreover, electrical characterization of the 4 nm thin film with capacitance-voltage and current-voltage have shown low leakage current densities and high dielectric constant. The tunable charge transfer and built-in electric field have laid down groundwork for developing functional heterojunction for energy harvesting purposes. Charge transfer and built-in electric field were reported across heterostructures of epitaxial SrNbxTi1-xO3-δ grown on Si (001). Transport measurement shows the formation of hole gas in Si. Hard x-ray photoelectron spectroscopy also shown asymmetries in core level spectra, which further confirm the built-in electric field across the heterojunction. The band bending due to built-in fields was spatially mapped out across the heterojunction with hard x-ray photoelectron spectroscopy. The wet etching study of complex oxide thin films and newly developed recipe could be used for fabrication of crystalline oxide sensing microdevices for future applications. I report here the study of wet etching of BaTiO3 and SrTiO3 films with HF Dip 10:1. The wet etching rate of BaTiO3 and SrTiO3 with different annealing conditions were determined using profilometer. The differences in etching rate for different annealing conditions are closely related to the bond density, crystallinity, and grain boundary of the films. A recipe was also developed to fabricate 156 nm BaTiO3 microbridge. Diffraction pattern image has proven the microbridge still preserve its crystallinity after processing.


Complex oxide, Molecular beam epitaxy, MBE, Oxide-semiconductor heterojunctions, MEMS


Physical Sciences and Mathematics | Physics


Degree granted by The University of Texas at Arlington

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