Graduation Semester and Year

2022

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Physics and Applied Physics

Department

Physics

First Advisor

Joseph Ngai

Abstract

Charge transfer and built-in fields across semiconductor heterojunctions underpin the functionality of virtually all device technologies. In this regard, interfaces between insulating oxides and semiconductors have been extensively studied due to the success of metal-oxide-semiconductor (MOS) technology. Perovskite oxides were originally proposed as potential replacements as a gate dielectric for MOS field-effect transistors because device scaling effects make SiO2 gate leakage too high. However, perovskite oxides containing transition metals display many other properties not found in semiconductors such as ferroelectricity, high-T superconductivity and metal-insulator transitions. Recent advancements in growth technology allow for the creation of structurally coherent interfaces between crystalline complex oxides and semiconductors, enabling the study of band alignment and charge transfer across them. Inherent to semiconductor-crystalline oxide interfaces is an interfacial dipole that modifies the structure near the interface. Key to realizing functional behavior at semiconductor-crystalline oxide interfaces is the ability to electrically couple their properties at the interface including band offsets and band bending. In this work we show that the interfacial dipole of a SrTiO3/Si heterojunction can be modified through space charge and surface termination to realize tunable band alignment across semiconductor-crystalline oxide interfaces. Additionally, a new method of deposition-last device patterning is discussed in which the substrate is patterned before film growth to circumvent the need for specific dry- and wet-etching processes typical of transition-metal oxides. The ability to tune band alignment and built-in fields across semiconductor-crystalline oxide heterojunctions opens a pathway to realize functional behavior in hybrid heterojunctions.

Keywords

Heterojunction, Band alignment, Interface dipole, Charge transfer

Disciplines

Physical Sciences and Mathematics | Physics

Comments

Degree granted by The University of Texas at Arlington

Included in

Physics Commons

Share

COinS