  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.
