The influence of Ag-doping was investigated on structural, electrical and microwave properties of pulsed laser deposited YBaCuO thin films on 3-inch diameter sapphire wafers. Up to now, no significant improvement of microwave surface resistance R, was found due to Ag-doping. However, Ag-doped YBCO films show a reduced surface roughness, improved homogeneity and reproducibiliry of Rs and critical current density, and no residues after wet chemical etching of stripline structures. Therefore, the pulsed laser deposition process seems to be assisted by Ag-doping of YBaCuO. The microwave surface resistance correlates with the degree of in-plane epitaxy of the YBCO:Ag thin films as measured by polarized Raman spectroscopy, and with the size of laser droplets in the films. Up to now, Rs of PLD-YBCO thin films remains constant at about 500 ufi (8.5 GHz, 77 K) and 180 ufi (19 GHz, 4.2 K) up to surface magnetic field of about 7 mT.
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