Electronic transport in quantum cascade structures

TL;DR

This paper presents a comprehensive theoretical model for electronic transport in complex quantum cascade detectors, accurately predicting device resistance without adjustable parameters and aligning well with experimental data.

Contribution

It introduces a parameter-free model for electron transport in multi-well quantum cascade structures, extending the Einstein relation to complex heterostructures.

Findings

Excellent agreement with experimental resistance measurements

Transport described by a sum of transition rates between subbands

Model applicable to complex structures with multiple quantum wells

Abstract

The transport in complex multiple quantum well heterostructures is theoretically described. The model is focused on quantum cascade detectors, which represent an exciting challenge due to the complexity of the structure containing 7 or 8 quantum wells of different widths. Electronic transport can be fully described without any adjustable parameter. Diffusion from one subband to another is calculated with a standard electron-optical phonon hamiltonian, and the electronic transport results from a parallel flow of electrons using all the possible paths through the different subbands. Finally, the resistance of such a complex device is given by a simple expression, with an excellent agreement with experimental results. This relation involves the sum of transitions rates between subbands, from one period of the device to the next one. This relation appears as an Einstein relation adapted to the case of complex multiple quantum structures.