Hot Carrier Dynamics in InAs-AlAsSb Core-Shell Nanowires

TL;DR

This study investigates hot carrier relaxation dynamics in InAs-AlAsSb core-shell nanowires, revealing key lifetimes and carrier behaviors that inform the design of high-efficiency photovoltaic devices.

Contribution

It provides new insights into hot carrier lifetimes and electronic states in InAs-AlAsSb core-shell nanowires using ultrafast spectroscopy, highlighting their potential for improved solar energy harvesting.

Findings

Hot electron lifetime of about 3 ps

Carrier-carrier interactions last around 3 ps

Excited carriers in the shell remain longer than 100 ps

Abstract

Semiconductor nanowires (NWs) have shown evidence of robust hot carrier effects due to their small dimensions. The relaxation dynamics of hot carriers in these nanostructures, generated by photo-absorption, are of great importance in optoelectronic devices and high efficiency solar cells, such as hot carrier solar cells. Among various III-V semiconductors, indium arsenide (InAs) NWs are promising candidates for their applications in advanced light harvesting devices due to their high photo-absorptivity and high mobility. Here, we investigate the hot carrier dynamics in InAs-AlAsSb core-shell NWs, as well as bare-core InAs NWs, using ultrafast pump-probe spectroscopy with widely tuned pump and probe energies. We have found a lifetime of 2.3 ps for longitudinal optical (LO) phonons and hot electron lifetimes of about 3 ps and 30 ps for carrier-carrier interactions and electron-phonon interactions, respectively. In addition, we have investigated the electronic states in the AlAsSb-shell and found that, despite the large band offset of the core-shell design in the conduction band, excited carriers remain in the shell longer than 100 ps. Our results indicate evidence of plasmon-tailored core-shell NWs for efficient light harvesting devices, which could open potential avenues for improving the efficiency of photovoltaic solar cells.