Ultrafast carrier dynamics in GaAs nanowires
Keywords: THz, nanowires, electronic transport, non-radiative centres
AbstractThe results of investigation of electronic transport in GaAs nanowires (NWs), which were grown by MBE and MOCVD on n-type GaAs(111) substrates are presented. The time-resolved dynamics of photocarriers were studied by opticalpump terahertz generation-probe time-domain spectroscopy. The dynamics of THz generation for different levels of excitation for the GaAs NWs grown by MBE can be explained by separation of photoinduced carriers in the contact field with subsequent screening of the contact field and with non-saturable carrier recombination. The dynamics of THz generation for the GaAs NWs grown by MOCVD is due to the growth of the mobility of carriers as they are being grabbed to the non-radiative centres and as a consequence of carrier retrapping. The shift of THz pulse is connected with the changes of a phase in transmission and reflection THz pulse through the border between the absorbing and non-absorbing medium.