Lingering Times at Resonance: The Case of Sb-based Tunneling Devices

TL;DR

This study investigates how stoichiometry influences the time-resolved optical responses and electron-hole dynamics in Sb-based resonant tunneling devices, revealing unique time scales linked to electronic structure and current flux.

Contribution

It demonstrates the impact of stoichiometry on qualitative and quantitative aspects of charge carrier dynamics in Sb-based tunneling devices, contrasting with As-based counterparts.

Findings

Stoichiometry significantly alters time-resolved optical responses.

Sb-based devices show distinct time scales related to electronic structure.

Current flux intensity affects relaxation times in Sb-based heterostructures.

Abstract

Concurrent natural time scales related to relaxation, recombination, trapping, and drifting processes rule the semiconductor heterostructures' response to external drives when charge carrier fluxes are induced. This paper highlights the role of stoichiometry not only for the quantitative tuning of the electron-hole dynamics but also for significant qualitative contrasts of time-resolved optical responses during the operation of resonant tunneling devices. Therefore, similar device architectures and different compositions have been compared to elucidate the correlation among structural parameters, radiative recombination processes, and electron-hole pair and minority carrier relaxation mechanisms. When these ingredients intermix with the electronic structure in Sb-based tunneling devices, it is proven possible to assess various time scales according to the intensity of the current flux, contrary to what has been observed in As-based tunneling devices with similar design and transport characteristics. These time scales are strongly affected not only by the filling process in the $\Gamma$ and L states in Sb-based double-barrier quantum wells but also by the small separation between these states, compared to similar heterostructures based on As.