THE EFFECT OF PHOTOOXIDATION ON THE STICKING AND REACTIVITY OF AG ON AMORPHOUS GES2

Photo-oxidation of amorphous GeS2 films illuminated by band-gap radiat ion drastically alters the growth mode and reactivity of subsequently deposited Ag. In the former case (monolayer/simultaneous multilayer gr owth) the Ag reacts with both Ge and S sites. In the latter case (Stra nski-Krastanov growth) Ge sites are selectively oxidized and film grow th proceeds by Ag nucleation at the unoxidized S sites. The behaviour is very different from that reported earlier for Zn deposition on GeS2 , where photo-oxidation results in very large changes in metal stickin g probability. XPS, XAES and EXAFS data provide the basis for understa nding both this phenomenon and the very different photodiffusion behav iour of Zn and Ag in GeS2.