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Multifunctional crystalline oxides on semiconductors: elevating the semiconductor-oxide heterojunction beyond the MIS paradigm

October 17, 2019 | 11:00 AM – 12:00 PM
Nedderman Hall 106 | Seminar Flyer

Seminar Speaker

Joseph Ngai, Ph.D.

Associate Professor, Physics Department, The University of Texas at Arlington


Heterojunctions between semiconductors and oxides form the foundation to field-effect transistors that have revolutionized information processing. However, their principal functionality remains as capacitors within the metal-insulator-semiconductor (MIS) paradigm. Advances in epitaxial growth now enable single-crystalline multifunctional oxides to be grown directly on semiconductors, opening a pathway to elevate the semiconductor-oxide heterojunction beyond the MIS paradigm. In this talk we will review the structural and electronic properties of multifunctional oxides and their epitaxial integration on semiconductors. In particular, we will discuss our recent efforts in achieving charge transfer and the formation of built-in potentials across SrNbxTi1-xO3-δ / Si(001) heterojunctions. We will discuss how electrical transport measurements combined with hard x-ray photoelectron measurements enable built-in fields to be spatially mapped across heterojunctions. Control of charge transfer and built-in fields could enable hybrid semiconductor-oxide pn-junctions, isotype junctions etc., to be realized; such heterojunctions could address emerging challenges in energy harvesting and information technology.


Dr. Joseph Ngai is an Associate Professor in the Dept. of Physics at the University of Texas-Arlington. After receiving his Ph.D. in physics from the University of Toronto, he was a Postdoctoral Fellow and Associate in the Dept. of Applied Physics at Yale University. His current research interests involve oxide thin-films and devices, with a particular focus on understanding how oxides can be electrically coupled to semiconductors to realize novel functional behavior.