Interface roughness transport in THz quantum cascade detectors

TL;DR

This paper investigates how interface roughness affects transport in THz quantum cascade detectors, using microscopy to measure roughness and modeling to understand its impact on device resistance.

Contribution

It introduces a novel approach to evaluate interface roughness parameters via STEM and analyzes their influence on transport properties in THz QCDs.

Findings

Interface roughness significantly impacts device resistance.

STEM provides detailed IR parameters beyond classical mobility measurements.

Modeling shows IR effects are critical in THz regime transport.

Abstract

Infrared Detectors based on a Quantum Cascade have been proposed to suppress the dark current which is identified as a limiting factor in Quantum Well Infrared Photodetectors. Those detectors have been mostly designed for the 3-5um and 8-12um range of wavelength. For detector operating in the THz range a complete change of regime of transport is expected since the photon energy is lower than the Longitudinal Optical (LO) phonon energy. Using a two dimensional code of transport we have identified Interface Roughness (IR) as the key interaction in such a structure. We have used scanning transmission electron microscopy (STEM) to evaluate the IR parameters (magnitude of the roughness and mean distance between defects) instead of the classical mobility measurements. Finally, we used these parameters to study their influence on the resistance of the device.