Influence of target-substrate angle on the elemental concentration of c-axis YBa₂Cu₃O_7-x thin films

The thermalization processes in sputtering suggest a spatial dependence of elemental concentration in the sputter plume. A variety of analysis techniques demonstrate that c-axis films grown at angles which deviate from the standard off-axis geometry produce nominally YBa₂Cu₃O_7-x in the bulk with dramatic changes in the surface morphology and deposition rate. In addition to the common materials characterization techniques of scanning electron microscopy, x-ray diffraction, transport measurements, and conventional Rutherford backscattering spectrometry (RBS), angle-dependent RBS is employed to probe surface inhomogeneities of films grown at target-substrate angles away from the standard off-axis position.