THE DIET FROM SEMICONDUCTOR SURFACES BY EXCITATION OF VALENCE-ELECTRONS

We discuss the desorption induced by electronic transitions (DIET) of constituent atoms from several types of non-metallic solids, particula rly the DIET from semiconductors by valence electron excitations. We f irst classify the non-metallic solids into type A, in which no self-tr apping of excitons occurs, and type B, in which self-trapping occurs. We argue that in type B solids the localization of electron-hole pairs or excitons through the self-trapping on the surfaces induces the Men zel-Gomer-Redhead-type anti-bonding state resulting in DIET. For the D IET from type A non-metals, typically semiconductors, in which the sel f-trapping is not induced, we derive two important characteristics: (1 ) the emission is related to defects on the surfaces and (2) single el ectronic excitation cannot induce the emissions. The recent experiment al observations of laser-induced emissions satisfying these characteri stics for the DIET from semiconductors are surveyed. Furthermore we pr esent experimental evidence demonstrating that the observed emissions are of the electronic origin: the emission occurs dominantly when the excitation is localized on the surface. Finally, surface phenomena, su ch as laser ablation and dry etching, related to the DIET from semicon ductors, and the applications of the DIET from semiconductors are disc ussed.