High-field transport in semiconductor superlattices for interacting Wannier-Stark levels

TL;DR

This paper presents a microscopic theory of electron transport in semiconductor superlattices considering Zener tunneling interactions, with Monte Carlo simulations showing how these interactions affect carrier energy and transport properties at high electric fields.

Contribution

It introduces a new theoretical approach incorporating Zener tunneling interactions into the Wannier-Stark model for superlattice transport, supported by Monte Carlo simulations.

Findings

Interaction causes a systematic increase in energy levels at high fields.

Carrier energy increases significantly, softening negative differential velocity.

Transport parameters are affected by Zener tunneling interactions.

Abstract

We develop a microscopic theory of electron transport in superlattices within the Wannier-Stark approach by including the interaction associated with Zener tuneling among the energy levels pertaining to adjacent quantum wells. By using a Monte Carlo technique we have simulated the hopping motion associated with absorption and emission of polar optical phonons and determined the main transport parameters for the case of a GaAs/GaAlAs structure at room temperature. The interaction among the levels is found to be responsible for a systematic increase of the level energy with respect to the bottom of the quantum well at electric fields above about 20 kV/cm. When compared with the non-interacting case, at the highest fields the average carrier energy evidences a consistent increase which leads to a significant softening of the negative differential value of both the drift velocity and diffusivity.