PHOTORESPONSE OF EPITAXIAL YBA2CU3O7-X ULTRATHIN FILMS

The voltage photoresponse of YBA(2)Cu(3)O(7-x)/SrTiO3 10 nm-thick film s on laser irradiation is studied using the low temperature scanning l aser microscopy (LTSLM) technique. The irradiation wavelength is 633 n m. The spatial response dependencies via temperature (4-100 K), beam i ntensity modulation frequency (0-150 kHz) and bias current are examine d. The bolometric and non-bolometric components are separated. The amp litude of the non-bolometric component at 4.2 K is about 10 times high er than that of bolometric one measured near the midpoint of the super conducting transition. The non-bolometric component is presumable asso ciated with weak links in the film due to interdiffusion of SrTiO3 int o YBCO layer. The spatial irregularity in superconducting parameters i s not resolved by the LTSLM method since the spacing between weak link s is appeared to be less than 1 mu m.