Revealing Charge Carrier Dynamics and Transport in Te-Doped GaAsSb and GaAsSbN Nanowires by Correlating Ultrafast Terahertz Spectroscopy and Optoelectronic Characterization

TL;DR

This study investigates how nitrogen doping affects charge carrier dynamics and transport in GaAsSb and GaAsSbN nanowires using ultrafast spectroscopy and electrical measurements, revealing increased scattering and reduced mobility due to N-induced defects.

Contribution

It provides the first detailed correlation between N incorporation, carrier dynamics, and optoelectronic properties in GaAsSbN nanowires using combined ultrafast spectroscopy and electrical characterization.

Findings

Nitrogen increases carrier scattering rate and reduces mobility.

Carrier lifetimes are 33 ps in GaAsSbN and 147 ps in GaAsSb.

Fast rise time (~2 ps) suggests potential for high-speed photodetectors.

Abstract

Recent advances in the growth of III-V semiconductor nanowires (NWs) hold great promise for nanoscale optoelectronic device applications. Recently, it was found that a small amount of nitrogen (N) incorporation in III-V semiconductor NWs can effectively red-shift their wavelength of operation and tailor their electronic properties for specific applications. However, understanding the impact of N incorporation on non-equilibrium charge carrier dynamics and transport in semiconducting NWs is critical in achieving efficient semiconducting NW devices. In this work, ultrafast optical pump-terahertz (THz) probe spectroscopy (OPTP) and electrical characterization have been used to study non-equilibrium carrier dynamics and equilibrium transport in Te-doped GaAsSb and dilute nitride GaAsSb NWs, with the goal of correlating these results with their photo-response under bias and their low-frequency noise characteristics. Nitrogen incorporation in GaAsSb NWs led to a significant increase in the carrier scattering rate, resulting in a severe reduction in carrier mobility. Carrier recombination lifetimes of 33 ps and 147 ps in GaAsSbN and GaAsSb NWs, respectively, were determined using ultrafast OPTP measurements. The reduction in the carrier lifetime and photoinduced optical conductivities are due to the presence of N-induced defects, leading to deterioration in the electrical and optical characteristics of dilute nitride NWs relative to the non-nitride NWs. Finally, we observed a very fast rise time of ~ 2 ps for both NW materials, directly impacting their potential use as high-speed photodetectors.