DETECTING PROPERTIES OF YBACUO THIN-FILM BRIDGES

The paper studies the properties of YBaCuO superconducting microbridges. They were fabricated by both direct photolitographic techniques and focused laser beam patterning. The YBaCuO thin films were deposited onto ZrO2, MgO, and SrTiO3 substrates by laser ablation of a massive YBaCuO target. Josephson effect was observed in the bridges by detecting Shapiro steps and "selective" response under irradiation with the signal frequency of 27-36 GHz. The value of product I(C)R(N) reached 4.5 mV at T = 4.2 K and 420-mu-V at T = 77 K. The best values for wideband sensitivity eta(T) and noise-equivalent power NEP(T) were eta(77) = 5x10(3) V/W, NEP(77) = 2x10(-12) W/Hz,1/2 eta(20) = 2.5x10(6) V/W, NEP (20) = 10(-14) W/Hz1/2. The estimation of noise by the width of selective response shows that the internal noise is 1.5-2.5 times higher than thermal value.