ABSTRACT

A great variety of consumer electronics, such as laptops and smartphones, rely on tiny nanometer-size electronic switches. To further improve and develop new electronic switches that can be manufactured more cheaply and consume less power, new device concepts based on novel two-dimensional materials rather than conventional silicon technologies have been proposed and new research is needed to assess their potential properties. An important step in the development of such new electronic switches is computer simulations incorporating the physical elements that control the charge transport. Many important breakthroughs have been realized in electronic transport simulations and quantum transport is routinely simulated using a host of tools available to the community. However, all of these currently available tools start from the chemist's "tight-binding" viewpoint rather than from the physicist's "plane-wave" vantage point. Unfortunately, certain physical processes that are important in two-dimensional materials are difficult to be treated correctly using the tight-binding basis. The goal of this project is to transform the way quantum transport is studied by moving from the tight-binding basis to the plane-wave basis. This project will develop a plane-wave based quantum transport code capable of studying novel electronic devices. The project will also include a study of conventionally-scaled electronic devices as well as newly proposed devices and materials that present important routes toward the realization of a more energy-efficient electronics. This project will also generate a pipeline of students motivated to study science and engineering at universities through participation in various outreach programs at the University of Texas at Dallas.

Specifically, the project will develop a plane-wave based code capable of studying quantum transport in nanoscale devices such as nanowires and nanoribbons. Efficient plane-wave algorithms to reduce computational memory and time requirements and a robust capability of studying the effects of spin-orbit coupling will be implemented in the code. Electronic dissipative scattering in these nanoscale devices will be dealt with using the Pauli Master equation. Important physical phenomena that will be incorporated are: scattering with phonons, defects, and edge roughness. Of particular interest is scattering with the flexural out-of-plane phonons which are hard to describe in a localized basis set. The atomic-scale dielectric response in these low-dimensional systems will also be studied. Using the developed quantum transport code, a wide variety of devices, such as conventional field-effect transistors, tunneling-based field-effect transistors, and topological-insulator field-effect transistors, will be studied. The research will elucidate the impact of flexural out-of-plane phonon modes on the electronic-transport characteristics of low-dimensional materials. The effects of spin-orbit coupling on transport will be determined. How the interplay between spin-orbit coupling and the electron-phonon interaction affects transport will be clarified. Finally, the research will also unravel the important physical processes in future field-effect transistors and determine how to deal with possible detrimental effects such as line-edge roughness.

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