Theory of the band-tail absorption saturation in polar semiconductors

Publisher Website
Google Scholar
Abstract
A theory is presented which allows one to calculate the absorption and its saturation in the band-tail region of polar semiconductors for elevated temperatures. The influence of the LO phonons and of the electron-hole plasma on the dynamically broadened band tail is considered. The problem is decomposed into the calculation of the broadening and the shift of the electron-hole pair states. Both the broadening and the shift are temperature and density dependent, although the shift of the 1s-exciton line depends mainly on the temperature alone. The calculation of the absorption saturation includes a self-consistent determination of the plasma density in terms of the intensity of the exciting laser light. The saturation of the absorption sets in after the light intensity exceeds a critical value which increases with decreasing frequency of the exciting laser light.