Application of emitter-sample hybrid terahertz time-domain spectroscopy to investigate temperature-dependent optical...

We investigate temperature-dependent carrier dynamics of InAs crystal by using reflection-type terahertz time-domain spectroscopy, particularly with a recently developed emitter-sample hybrid structure. We successfully obtain the optical conductivity in a terahertz frequency of bulk InAs whose dc conductivity is in the range of 100-150  Ω^-1 cm^-1. We find that both real and imaginary parts of the optical conductivity can be fit well with the simple Drude model, and the free-carrier density and the scattering rate obtained from the fit are in good agreement with corresponding values obtained by using other techniques, such as the Hall measurement and the dc-resistivity measurement. These results clearly demonstrate that the proposed technique of adopting the emitter-sample hybrid structure can be exploited to determine temperature-dependent optical constants in a reflection geometry and hence to investigate electrodynamics of bulk metallic systems.