Full-Band Quantum Transport of Heterojunction Electron Devices with Empirical Pseudopotentials

This article presents the methodology, implementation, and application of a full-band quantum transport model based on the nonequilibrium Green's function formalism and the empirical pseudopotentials. In particular, this article reports the treatment of heterojunctions between lattice-matched semiconductors, comprising a gradual transition region described according to a virtual crystal approximation. Our approach entails several numerical techniques to make the full-band quantum transport method computationally affordable and thus enable robust and efficient self-consistent device simulations. Then, we employ our simulation scheme for the analysis of some exemplary devices based on quantum tunneling, such as an Esaki tunneling diode, as well as n- and p-type heterojunction tunnel FETs. In particular, we investigate the influence on the current-voltage characteristics of the width of the heterojunction transition region. We observe that a gradual transition region mainly affects the device characteristics by lengthening the tunneling path at the heterojunction, which has a different impact on device current depending on the external bias conditions.