Ultrafast photodetection in the quantum wells of single AlGaAs/GaAs-based nanowires

TL;DR

This study explores the ultrafast optoelectronic responses of single AlGaAs/GaAs nanowires with quantum wells, revealing distinct charge carrier dynamics and potential for ultrafast photodetectors and photoswitches.

Contribution

It provides new insights into the charge carrier dynamics in quantum well nanowires and demonstrates their potential for ultrafast optoelectronic applications.

Findings

Resonant excitation induces picosecond photocurrent via lateral charge expansion.

Dember-effect observed in quantum wells but not in the core.

Core exhibits ultrafast displacement and thermoelectric currents.

Abstract

We investigate the ultrafast optoelectronic properties of single Al0.3Ga0.7As/GaAs-core-shell-nanowires. The nanowires contain GaAs-based quantum wells. For a resonant excitation of the quantum wells, we find a picosecond photocurrent which is consistent with an ultrafast lateral expansion of the photogenerated charge carriers. This Dember-effect does not occur for an excitation of the GaAs-based core of the nanowires. Instead, the core exhibits an ultrafast displacement current and a photo-thermoelectric current at the metal Schottky contacts. Our results uncover the optoelectronic dynamics in semiconductor core-shell nanowires comprising quantum wells, and they demonstrate the possibility to use the low-dimensional quantum well states therein for ultrafast photoswitches and photodetectors.