MAPPING THE VARIATIONS IN PROPERTIES OF PLD FILMS OF YBCO DEPOSITED OVER LARGE AREAS

In the context of developing laser-ablated epitaxial thin films for de vice applications a number of technological problems have yet to be so lved including some related to the reproducibility and reliability of properties over large areas. At present single crystal MgO-substrates of 10x10 mm(2) are often used for reasons of convenience even though m any applications-especially microwave devices-would benefit significan tly if larger area substrates and thin films of high quality became av ailable, The advantages of high flexibility and relative inexpensivene ss of pulsed laser deposition goes hand-in-hand with rather severe res trictions on the areas over which layer-uniformity and homogeneity can be readily obtained. Here we will report the results of an investigat ion into the variations of properties found in YBCO-films on MgO-subst rates positioned over an area of 5 cm diameter. The process parameters used were those typically producing smooth films of approximately 300 nm thickness with good microwave properties. The films were assessed by atomic force microscopy, and Rutherford backscattering spectrometry .