Bolometric response of YBCO thin films to blackbody radiation

The possibility for utilization of high Tc superconducting films, based on Y1Ba2Cu3O7-x,(YBCO) as bolometric sensors and the performance of experimental structures exposed to blackbody radiation is discussed. The used analytical model is based on 1D Fourier heat conduction equation for film-buffer substrate system neglecting the lateral heat conduction on the surface. The high thermal resistance of the interface film/buffer layer and the small film thickness (0.5μm) imply on the existence of multiple reflection of the incoming wave. The results indicate that the response on frequency dependence follows 1/ω1/2 law instead of 1/ω one which is typical for the classical thermal detectors. The performance of the experimental sensor based on YBCO superconducting films is tested and compared to the theory. The resistance/temperature and temperature difference/chopping frequency dependence were studied. It is concluded that only superconducting films with high perfection are suitable. The device performance is feasible especially in the MIR and FIR range where low-cost and precise detectors are necessary. Currently, the detector performance is being improved by decreasing the film thickness (about 100 nm) and by thermal isolation of the sensing area using bridging structures and membranes. 6 figs., 11 refs