Monte Carlo simulation of the dember effect in n-InAs exposed to femtosecond pulse laser excitation

The Monte Carlo simulation is used to calculate the Dember photovoltage and study the generation of terahertz electromagnetic pulses excited in indium arsenide by femtosecond laser radiation. The dynamics of the electric field and the chargue-carrier transport are treated self-consistently. It is shown that the excitation of a semiconductor by laser pulses with the photon energy of h omega <= 1.5 eV, the photovoltage attains its maximum within 50-100 fs after excitation and then falls off, oscillating with the plasma frequency. The photovoltage peak can be as much as tens times higher than the typical Dember photovoltages induced by steady-state illumination. On excitation of the semiconductor by radiation with shorter wavelengths (h omega >= 1.6 eV), the photoelectrons are scattered to the L and X valleys side; as a result, the photovoltage and the efficiency of the generation of the terahertz emission decrease.