Carrier Thermalization Dynamics in Single Zincblende and Wurtzite InP Nanowires

Abstract

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 NWs reveals more than an order of magnitude slower relaxation for the InP NWs. We interpret these results as reflecting their distinctive phonon band structures that 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.

Antimony Induced {112}A Faceted Triangular GaAs1−xSbx/InP Core/Shell Nanowires and Their Enhanced Optical Quality

“…The dramatic increase in PL intensity for the GaAs 1− x Sb x /InP core–shell NWs over the GaAs 1− x Sb x bare core suggests a strong reduction in nonradiative recombination at the surface of the NWs. Transient Rayleigh scattering (TRS) spectroscopy has been shown to be a powerful technique to study the band structure, carrier thermalization dynamics, and carrier lifetime of single nanowires . The change of polarized Rayleigh scattering efficiency from the nanowire is defined as where () represents the back‐reflected Rayleigh scattering of the nanowire with incident light polarized parallel (perpendicular) to the nanowire.…”

“…The NW was excited using a 632 nm continuous wave (CW) laser and the emission was detected with a linear InGaAs p‐i‐n photodetector array. For TRS experiments, NWs were dispersed onto a marked Si substrate and placed onto the copper cold finger of a constant helium flow cryostat. The NW was photoexcited by a pump pulse (550 nm) extracted from a Fianium supercontinuum source.…”

Ultrafast Dynamics of Lasing Semiconductor Nanowires

“…However, the carrier 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 temperature can be expected to be even higher in CdS and ZnO, since the optical excitation energy relative to the bandgap energy is larger here [40]. Thus, the ELR in CdS and ZnO is even more increased.…”

Space-and-time-resolved spectroscopy of single GaN nanowires

“…These issues can be overcome by performing ultrafast optical pump-probe measurements on single NWs, [20][21][22][23][24][25][26][27][28] which has provided much insight into their intrinsic properties. For example, ultrafast optical microscopy (UOM) experiments, which are essentially optical pump-probe experiments with microscopic spatial resolution, have been performed on single Si NWs, revealing the dependence of carrier dynamics on light polarization and excitation fluence 25 as well as the NW diameter.…”

“…22,25 This may indicate that the relaxation of carriers trapped in defect states is not very sensitive to the NW diameter, particularly at the larger diameters examined here, unlike the carriers in above-band gap extended states probed in other studies. [20][21][22][23][24][25][26] We then performed pump fluence-dependent measurements on the single GaN NW to explore the influence of the photoexcited carrier density on carrier dynamics ( Figure 3(a)). The data clearly show that carrier relaxation gets faster with increasing fluence (Fig.…”