As the field of topological materials rapidly evolves, demonstration of scalable applications still remains challenging due to practical hurdles such as rapid prototyping of new topological insulator (TI) compounds, and efficient probing of topological surface states (TSS) for device applications. My PhD research endeavored to take a two-pronged approach to this end: to address the challenges of reliable material growth and to explore TI transport physics. We demonstrate first-time van der Waals epitaxial (vdWE) growth of crystalline Bi2Te2−xS1+x (BTS) nanosheets. We perform detailed transport measurements on BTS devices, observing signatures of TSS and mesoscopic effects such as electron-electron interactions, weak antilocalization and universal conductance fluctuations, along with providing a sound picture of multiple parallel transport channels in TI devices. We then demonstrate a versatile process for large-area custom-feature TI growth and fabrication, achieved through lithographic selective-area modification of surface free-energy on mica. TI features grow epitaxially in large single-crystal trigonal domains with highly oriented crystalline edges. Unusual nonlinear thickness dependence and denuded zones are observed, explained by semi-empirical surface migration modeling with robust estimates of growth parameters. TSS contribute up to 60% of device conductance at room-temperature, indicating excellent electronic quality. The process is constructed from highly adaptable microfabrication technology, customizable for 2D vdW materials device fabrication processes ranging from rapid prototyping to scalable manufacturing. I will briefly discuss ongoing work in developing applications of TIs for memory and microwave devices. I will also provide a brief overview on some of our collaborative work on developing on-chip chemical sensors and studying collective EM phenomena in magnetoinductive waveguides geared towards sensing applications. I will conclude by motivating future research directions combining some of the themes for application development.
Tanuj Trivedi received his PhD in Electrical and Computer Engineering from The University of Texas at Austin in 2017, specializing in Solid-state Electronics. His PhD research focused on solving implementational challenges of topological insulators for practical device applications. He has a background in solid-state electronics, micro/nanofabrication, thin film growth, sensors, and RF instrumentation. He earned his MSE in Electrical and Computer Engineering from UT Austin in 2012, and B.Tech. in Electronics and Communication Engineering from Nirma University, India in 2008, after which he worked as Staff Scientist/Engineer at the Indian Space Research Organisation before joining UT.