ELECTRON-HOLE ORDERING AND 1 OMEGA NOISE IN AMORPHOUS-SEMICONDUCTORS/

Theoretical and experimental studies of amorphous semiconductors As2S5 show that photogenerated trapped electrons and holes are strongly cor related. The Fourier transform of the electron (hole) density time flu ctuations (and, hence, of the refractive index variations) indicates t hat universal 1/omega noise is present in an ordered state, while diso rdered electron-hole systems give white noise. We give experimental ev idence of this 1/omega noise in AS(2)S(5) in support of the idea of el ectron-hole self-organization under light pumping.