Abstract

Our previous studies of integral characteristics of excitonic absorption bands in a number of typical layer semiconductors led us to some conclusions on the pecularities of relaxation mechanisms responsible for excitonic absorption. In particular, the nonlinear exciton-phonon interaction, indirect phototransitions and phonon anharmonism are all important (1). They are related to the pecularities in vibrational spectrum of layer crystals: the existence of bending waves in acoustic phonon spectrum and low-energy optical phonons (LOP) with ħω= 1÷3 meV due to extrinsic inter-layer vibrations.

© 1984 Optical Society of America