High-field nonlinear conductivities of n- and p-type GaAs thin films in the terahertz region

We investigated high-field terahertz (THz) responses and the nonlinear conductivities of n- and p-type GaAs thin films in the THz region. As the THz pulse intensity was increased to 59 μJ/cm², the THz transmission of the n-type GaAs thin film was significantly increased, more than that of the p-type film. This result is correlated with the conductivity of the electronic system caused by scattering processes. Intervalley scattering was dominant in n-type GaAs, whereas hot-cold hole interactions and intervalence band transitions were the main factors reducing the conductivity in p-type GaAs. In addition, we extracted the frequency-domain conductivity of the n- and p-type GaAs thin films and used the Drude-Smith model to explain non-Drude-like behavior due to high-field excitation.