MODEL OF LEAD LOSS IN PB(MGXNB1-X)OZ ION-BEAM SPUTTERED THIN-FILMS

Thin films of Pb(Mg(x)Nb1-x)O(z) (hereafter called PMN) have been depo sited on carbon substrate by reactive ion beam sputtering, from a mixe d oxide-metal multicomponent target composed of magnesium oxide, and m etallic niobium and lead. The substrate temperature and sputtering gas composition (oxygen pressure during deposition) were varied and their effects on the film composition and compositional uniformity were inv estigated. The major effect seen was the systematic variation in Pb co ntent with changes in temperature and gas composition. We also observe d a spatial variation in Pb composition across the substrate and belie ve this to be caused by film bombardment by argon ions specularly refl ected by the target surface. This was supported by results showing a s ystematic reduction in Pb content in films subjected to secondary ion bombardment during film growth. The selective Pb depletion in PMN film s is discussed in terms of various mechanisms found in reactive sputte ring environments.