Light absorption in disordered semiconductors with a random Coulomb-type field

A method is proposed for the formulation of an asymptotic series for the light absorption coefficient in disordered semiconductors with a random field of the Coulomb type. It is shown that the series is obtained by expanding the exponent of an exponential function in powers of a parameter proportional to (E_g–)^–1/3, where E_g is the band gap of the semiconductor, and is the photon energy. The first three terms of the series are calculated in explicit form.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 28–32, January, 1988.