Detecting properties of YBaCuO thin film bridges

A study is made of the properties of YBaCuO superconducting microbridges. They were fabricated by both direct photolithographic 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. The Josephson effect was observed in the bridges by detecting Shapiro steps and selective responses under irradiation with a signal frequency of 27-36 GHz. The value of the product I_cR_N reached 4.5 MV at T=4.2 K and 420 μV at T=77 K. The best values for wideband sensitivity η(T) and noise-equivalent power NEP(T) were η(77)=5×10³ V/W NEP(77)=2×10^-12 W/Hz^1/2 η(20)=2.5×10⁶ V/W, and NEP(20)=10^-14 W/Hz^1/2. The estimation of noise by the width of the selective response shows than the internal noise is 1.5-2.5 times higher than the thermal value