PREPARATION, PATTERNING AND PROPERTIES OF YBCO FILMS

YBCO films were prepared on various single-crystalline substrates, (100)-oriented LaAlO 3 , SrTiO 3 , MgO, randomly oriented Zr(Y)O 2 and r-plane sapphire, by Inverted Cylindrical Magnetron Sputtering (ICMS). The surface morphology was investigated by scanning electron microscopy (SEM). The inductively measured T c values of the films “as prepared” ranged from 87 to 90K. The j c values at 77K of films on (100) LaAlO 3 and SrTiO 3 were 5 · 10 6 and 4 · 10 6 A/cm 2 , respectively. j c of films on r-plane sapphire was 5 · 10 4 A/cm 2 . The surface resistance R s was measured using a 67 GHz resonator made of copper. R s of a 0.4μm thick YBCO film on LaAlO 3 was 17mω at 77K. All the films were highly c-axis textured with small admixtures of a-axis oriented grains. Microstrips of a width down to 2μm were patterned by means of conventional UV-photolithography. The etch step was performed in diluted phosphoric acid or EDTA. Measuring T c of the microstrips as a function of their width, we found that the T c -degradation starts at 8μm using phosphoric acid but not above 2μm using EDTA.