  Using transient Rayleigh scattering (TRS) measurements, we obtain
photoexcited carrier thermalization dynamics for both zincblende (ZB) and
wurtzite (WZ) InP single nanowires (NW) with picosecond resolution. A
phenomenological fitting model based on direct band to band transition theory
is developed to extract the electron-hole-plasma density and temperature as a
function of time from TRS measurements of single nanowires which have complex
valence band structures. We find that the thermalization dynamics of hot
carriers depends strongly on material (GaAs NW vs. InP NW) and less strongly on
crystal structure (ZB vs. WZ). The thermalization dynamics of ZB and WZ InP NWs
are similar. But a comparison of the thermalization dynamics in ZB and WZ InP
NWs with ZB GaAs NW reveals more than an order of magnitude slower relaxation
for the InP NWs. We interpret these results as reflecting their distinctive
phonon band structures which lead to different hot phonon effects. Knowledge of
hot carrier thermalization dynamics is an essential component for effective
incorporation of nanowire materials into electronic devices.
