Advancing carrier transport models for InAs/GaSb type-II superlattice MWIR photodetectors

TL;DR

This paper enhances carrier transport modeling for InAs/GaSb superlattice photodetectors by integrating advanced scattering mechanisms and band structure calculations, leading to more accurate predictions of mobility and conductivity.

Contribution

It advances Rode's method with k.p band structure and envelope function approximation to improve carrier transport modeling in superlattices, highlighting the roles of various scattering mechanisms.

Findings

Elastic and inelastic scattering mechanisms are crucial for accurate modeling.

Temperature and carrier concentration significantly influence Hall mobility.

Deviations of the Hall scattering factor from unity affect mobility estimations.

Abstract

In order to provide the best possible performance, modern infrared photodetector designs necessitate extremely precise modeling of the superlattice absorber region. We advance the Rode's method for the Boltzmann transport equation in conjunction with the $\bf k.p$ band structure and the envelope function approximation for a detailed computation of the carrier mobility and conductivity of layered type-II superlattice structures, using which, we unravel two crucial insights. First, the significance of both elastic and inelastic scattering mechanisms, particularly the influence of the interface roughness and polar optical phonon scattering mechanisms in technologically relevant superlattice structures. Second, that the structure-specific Hall mobility and Hall scattering factor reveals that temperature and carrier concentrations significantly affect the Hall scattering factor, which deviates significantly from unity even for small magnetic fields. This reinforces the caution that should be exercised when employing the Hall scattering factor in experimental estimations of drift mobilities and carrier concentrations. Our research hence offers a comprehensive microscopic understanding of carrier dynamics in such technologically relevant superlattices. Our models also provide highly accurate and precise transport parameters beyond the relaxation time approximation and thereby paving the way to develop physics-based device modules for mid-wavelength infrared photodetectors.