Phonon-assisted sequential tunneling in biased quantum well structures

Abstract

We present a theoretical analysis of electron and hole escape mechanisms from a quantum well (QW) in an external electric field. The influence of carriers and dopant ion charges on the band structure is simulated with a self-consistent Poisson-Schrödinger solver. A new escape mechanism called the phonon-assisted sequential tunneling is proposed as an alternative to direct tunneling and thermionic emission from the QW ground state. Our calculation shows that at high forward biases, POP phonon-assisted sequential tunneling and thermionic emission dominate the electron and hole escape times. At high reverse biases, direct electron tunneling from the QW ground state to the reservoir determines the turn-off time constant, while heavy holes take a longer time to escape than electrons.