THEORY OF PHOTOVOLTAIC EFFECTS IN CRYSTALS WITH A COMPLEX BAND-STRUCTURE UNDER CONDITIONS OF 2-PHOTON ABSORPTION OF LIGHT

The mechanisms of the linear photovoltaic effect in crystals with a co mplex energy band structure under the conditions of two-photon absorpt ion of light have been theoretically analyzed. The frequency and tempe rature dependences of the current due to the photo mechanism of the ba llistic linear photovoltaic effects have been obtained in an approxima tion quadratic with respect to the wave vector assuming the energy spe ctrum of free carriers. The temperature dependence of the displacement current, the two-photon linear photovoltaic effect, has been analyzed . The current due to the ballistic effect, which is a quadratic functi on of the intensity of the exciting light, was found to be detectable in crystals without an inversion center.