MgO substrate surface optimization for YBaCuO thin film growth

To obtain high quality Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ (YBaCuO) films grown on [001] MgO substrates, we have investigated the influence of high temperature substrate annealing prior to film deposition. In particular, we discuss the effect of annealing conditions (atmosphere, temperature and time) on MgO substrate morphology observed with atomic force microscopy. Thermal treatment under specific conditions resulted in the formation of [001]-oriented terraces bounded by [100]-oriented steps on the substrate surface. An improvement in the crystalline quality, as well as better DC electrical properties and microwave surface resistance values, has been observed for films sputtered onto substrate surfaces exhibiting such regular nanoscale step structures.