Температурні трансформацiї смуг екситонного поглинання в iонному напiвпровiднику зі слабким електрон-фононним зв'язком

Abstract

In the approximations of dielectric continuum for phonons and within the effective masses for electrons the effect of longitudinal optical phonons on the formation of exciton spectra in polar semiconductors is determined by the Green s function method The calculations have been made using the Mott-Vannier model of exciton in n S-states ( n = 1, 2, 3) for a semiconductor compound CdS as an example The results obtained make it possible to confirm that interaction of exciton with the longitudinal optical phonons manifest itself in the shift of absorption band peaks to low-energy region. The value of the shift varies for different states and depends on the temperature. This may be the cause of the violation of serial regularities of exciton absorption bands Unlike the main one ( n = 1) the temperature change of the position of the peaks and of the width of higher exciton bands as a result of interaction with optical phonons is considered to be nonessential.