Temperature sensitivity and noise of Josephson detector on bicrystal sapphire substrates at 77 K
Journal article, 2007
In YBa 2 Cu 3 O 7 - x films grown on sapphire bicrystal substrates, the Josephson junctions are prepared based on artificial grain boundaries formed by the turn of the crystal lattices about the  axis. The films are deposited by the laser ablation method on the buffer CeO 2 layer. The critical film temperature reaches 88.5 K with a transition width of 1.5 K. Junctions from 2 to 3-μ m wide are integrated into the planar log-periodic antennas and their characteristics are measured at 77 K. The characteristic voltage I c R n reaches 570 μV. With exposure to external radiation at a frequency of 113 GHz, the Shapiro steps were observed on the current-voltage characteristic. The temperature sensitivity of this detector placed in a quasi-optical receiving unit is measured. At the modulation of the input radiation temperature 77 K/300 K, a response of more than 200 nV is observed at the detector output. At the modulation frequency, intrinsic noise is about 1 nV/Hz 1/2 , which corresponds to a temperature resolution of 1 K. © 2007 Pleiades Publishing, Ltd.