Creation of long-living ordered electron-hole structures in a disordered system: Slow nonlinear response and formation of a beam channel by weak pumping.

Abstract

Experimental and theoretical studies of an amorphous As 2 S 5 semiconductor show the appearance of a nonlinear variation of the refractive index Δn e produced by a weak He-Ne laser beam. The refractive-index variation needs long-time exposure (hours) and survives for a long time (a few days) after the laser is switched off. The main feature of the theoretical model proposed here is the existence of electron and hole trapped states resulting in slow relaxation and recombination, and the dependence of generation and recombination rates in a given trap on the space distribution of electron-hole ordering