Study of quantum transport in nanoscale structures using non-equilibrium Green's function method

This thesis discusses physics and numerical modeling related to quantum transport in nanoscale semiconductor devices. The non-equilibrium Green's function (NEGF) method, also called Keldysh Green's function method, is used to solve the quantum transport problem. NEGF is applied to quantum transport problems in multi-terminal devices, including a new formulation to account for the effect of magnetic field. A direct solution method for Green's function in a multi-terminal device is developed. With the inclusion of magnetic field in a 2-D electron gas, the method is used to simulate the integer quantum Hall effect (IQHE). Comparisons with experiments have been made using a realistic device structure, achieving more detailed representation of physics compared with previous simulation work. An iterative NEGF method has been developed to study 3-D structures with elastic acoustic and inelastic optical phonon scatterings calculated self-consistently. Results from NEGF method are compared with Monte Carlo simulation for a quantum wire structure. Physics effects in various nanoscale structures have been studied. With this general implementation, NEGF has been applied to study directional transport in coupled quantum channels and terahertz photo-response in double quantum wells. The NEGF solution schemes have been implemented in high-performance parallel codes optimized for computer clusters.