Transport in semiconductor superlattices: from quantum kinetics to terahertz-photon detectors

TL;DR

This paper reviews quantum transport theories in semiconductor superlattices, explores their application in THz-photon detection, and demonstrates how device performance can be optimized through physical mechanisms like Bloch-plasma oscillations.

Contribution

It introduces a first-principles quantum transport theory encompassing standard models and analyzes superlattice devices as circuit elements for enhanced THz detection.

Findings

Quantum transport theory maps out validity boundaries of existing models.

Superlattice devices can be optimized for THz detection performance.

Hybrid Bloch-plasma oscillations enhance responsivity.

Abstract

Semiconductor superlattices are interesting for two distinct reasons: the possibility to design their structure (band-width(s),doping, etc.) gives access to a large parameter space where different physical phenomena can be explored. Secondly, many important device applications have been proposed, and then subsequently successfully fabricated. A number of theoretical approaches has been used to describe their current-voltage characteristics, such as miniband conduction, Wannier-Stark hopping, and sequential tunneling. The choice of a transport model has often been dictated by pragmatic considerations without paying much attention to the strict domains of validity of the chosen model. In the first part of this paper we review recent efforts to map out these boundaries, using a first-principles quantum transport theory, which encompasses the standard models as special cases. In the second part, focusing in the mini-band regime, we analyze a superlattice device as an element in an electric circuit, and show that its performance as a THz-photon detector allows significant optimization, with respect to geometric and parasitic effects, and detection frequency. The key physical mechanism enhancing the responsivity is the excitation of hybrid Bloch-plasma oscillations.