In this thesis, a quantum device simulator based on Wigner function formulation has been developed to model DC and transient behaviors of resonant tunneling diodes (RTDs). The Wigner function is formulated in a discrete approximation for the solution of the Wigner function transport equation, or Liouville equation in steady-state. The transient response is obtained by numerical integration of the Liouville equation. Inelastic scattering due to electron-phonon interactions is included in both steady-state and transient simulations. A self-consistent Wigner-Poisson iteration has been carried out to include Hartree potentials which are originated from electron-electron repulsive forces.
The accuracy of the developed model is verified by comparing the calculated I-V characteristics and transient response of RTDs with the previous results from existing Wigner function models for RTDs found in the literature. The model developed in this work is applied to the simulation of pseudomorphic $In_{0.53}Ga_{0.47}As/AlAs$ subwell RTDs to investigate the relationship between intentional variations in the structural design parameters (i.e., barrier height, barrier thickness, quantum well width, and quantum well composition) and the terminal device I-V characteristics. The simulated I-V characteristics of the subwell RTDs are compared with the measured results. Finally, design guidelines for improving the DC characteristics of the subwell RTDs have been investigated and summarized.
