Anisotropic Photoconductivity and Terahertz Emission from Semiconductors

Abstract

In this report we consider the anisotropic photoconductivity in a semiconductor excited by two-frequency optical radiation, as well as its contribution to the photocurrent at the beat frequency corresponding to the THz region. The interband anisotropic photoconductivity arises due to the anisotropy of the momentum distribution of electrons excited by polarized light and the energy dependence of the momentum relaxation time and effective mass of the electrons. The response time of the anisotropic photoconductivity is very short, since it is determined by the electron momentum relaxation time, which for typical semiconductors is about 200 – 300 fs.