Carrier transport in dirac-band materials and their device physics.

摘要

Dirac-band materials have recently become one of the most promising materials under research for the prospects of designing low-power high-speed computing devices for future applications, an objective which can no longer be sustained via scaling down of silicon channel in transistors. The Dirac-band materials, at least the ones studied in this work (Group-IV monolayer elements and Bi2Se3 topological insulator), generally have very high drift velocity, good thermal properties to avoid hot-spots in the devices, and have spin-polarized bands either intrinsically or can be easily made so by magnetic dopants or just electric field, which make them especially attractive for engineering pure or hybrid spintronic applications. The device design with Dirac-band materials mandates the understanding of the carrier transport in these materials. The understanding of charge and spin flow in Dirac-band materials is critical for this purpose. The nanoscale dimensions of these materials exhibit strong quantum mechanical characteristics which warrant a quantum transport simulator. Non-equilibrium green function (NEGF) formalism is one such quantum algorithm for studying carrier transport in complex mesoscopic systems in both ballistic and diffusive regime, provided it is computationally feasible. This thesis, therefore, computationally investigates the carrier (charge and spin) transport in Dirac-band materials and some of their prospective devices generally via NEGF based on tightbinding Hamiltonian. (Abstract shortened by UMI.).