CAREER: Tailoring the Surface State Conduction in Semiconductor and Topological Insulator Nanowires

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This CAREER award is jointly funded by the Electronic and Photonic Materials Program (EPM) and Condensed Matter Physics Program (CMP), both in the Division of Materials Research.Technical: Due to the ubiquitously large surface-to-volume ratio of nanomaterials, surface and interface effects are essential to their electronic and optoelectronic properties. The research component of this CAREER award focuses on the fundamental study and control of surface state conduction in nanowires of indium arsenide and bismuth compounds (e.g., bismuth selenide or telluride), two model systems of the conventional III-V semiconductors and the recently discovered topological insulators. In conventional semiconductor nanowires, surface states generally degrade the material's performance and are often undesirable. However, for topological insulators, the topological surface states are the subject of interest for both basic research and potential device applications, and thus should be protected against the bulk states, which have been hindering the progress in the topological surface state research. In this research project, surface functionalization, doping and heterostructured material design are employed experimentally to tailor the surface conduction in semiconductor and topological insulator nanowires. These material and synthetic controls of the surface are further complemented by the conductance and capacitance spectroscopy for the quantitative understanding and evaluation of the surface versus bulk transport in nanowiresNon-technical: Nanowires have become an important material platform in modern nanoelectronics and photonics. Since nanomaterials have very high surface to volume ratio, surface effects could dominate the overall electronic properties and greatly impact the material performance. This CAREER project aims to achieve a comprehensive understanding of and precise control over the electronic surface states in nanowires of either conventional semiconductor or the recently discovered topological insulator materials. The research activities are expected to benefit multiple areas in which nanomaterials are playing an essential role. With this CAREER project, the PI also seeks to establish an education program integrated with the research project at Case Western Reserve University. Both graduate and undergraduate students engage actively in the project and learn state-of-the-art nanoscience and technology. In addition, pre-college students in the Cleveland area are being outreached through collaborations with a local girls' school and an inner city school with 100 percent of students receiving subsidized lunches. These outreach efforts are made to stimulate young students' interest and enthusiasm in pursuing science and technology as a future career. Further education and outreach endeavor of this project includes the development of a layman-level interactive web page and nanoscience course/lecture development related to the research activity.