Strontium Stannate – An Emerging Wide Gap Semiconductor for Field-Effect Transistor Applications

Abstract

Perovskite oxides are a promising family of materials with the potential for enabling the development of advanced novel electronic device components. However, the lack of an appropriate channel material has hindered the development of game-changing perovskite-based electronic devices. Perovskite stannates are emerging tin-based perovskite oxide semiconductors that have all the requisite material properties for a channel material and are capable of high electron mobilities at unusually high carrier concentrations. Among the perovskite stannates, barium stannate (BSO) has been the most popularly researched material. Strontium stannate (SSO), another interesting perovskite stannate, has been relatively less explored, even though by virtue of its smaller lattice constant, it is more amenable for heterostructure growth than BSO and for eventual integration with other perovskite oxide materials of novel technological interest. SSO also has a wide band gap in the range of 4-5 eV, which makes it particularly well suited to high-power and radio frequency (RF) applications. These properties provided us enough motivation to explore SSO for field-effect transistor (FET) applications. In this dissertation, the demonstration of first-ever SSO-based FETs with record performance for any stannate-based FET is presented. Further, the challenge of producing low resistance ohmic contacts to SSO is addressed through a systematic study, and optimized contacts for use in FETs are demonstrated. Improvement in performance over our previously reported SSO-based FETs is presented by utilizing a bi-layer film structure and RF operation in SSO-based FETs is also reported. This study lays the foundation for the development of future high-performance and novel perovskite devices.