Cation Deficiencies in RF Sputtered Gadolinium Iron Garnet Films

RF sputtering of stoichiometric, polycrystalline gadolinium iron garnet material results in films significantly deficient in iron content. The cation deficiency is shown to be quite sensitive to preparatory conditions and reflects itself markedly in the magnetic and structural properties of the resultant films. Temperature dependent sticking probabilities and selective resputtering at the growing film surface are thought to be the most likely causes for the observed deficiencies. A simultaneously operated rf-dc two-target sputtering system is described in some detail, which allows an expeditious study of and subsequent compensation for the observed cation deficiency. Films with essentially the bulk garnet composition and bulk structural and magnetic properties were prepared in this two target system.