酸化物超伝導体による赤外線検出素子

概要

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This paper reviews highly sensitive infrared optical detectors using super-conducting oxide thin films. Oxide Superconductors have smaller reflection coefficients than metal superconductors, and therefore infrared light can more easily penetrate into the films. Photons destroy Cooper-Pairs there and, in turn, create quasi-particles. The accumulation of quasi-particles decreases the superconducting energy gap 2 Δ (that is, the superconducting order parameter). The decrease shifts the I-V curves due to Josephson junctions along the grain boundaries, and therefore optical signals can be detected by those changes. The sensitivity obtained for BaPb_<0.7> Bi_<0.3> O_3 is about 10^<14>V/W in the infrared region. The response time is very short and near 1 ns. Since the discovery of high Tc superconductors, optical detectors of those materials have been studied. Detection with YBa_2 Cu_3 O_7 or T1-Ba-Ca-Cu-O thin films also has been found to be attributed to the same nonequilibrium pairbreaking effect (that is, generation and accumulation of quasiparticles), and both films have the sensitivities of about 20 V/W. Bao.6 K_<0.4> Bio_3 thin films show sensitivity of about 300 V/W and the same response time as BaPb_<0.7> Bi_<0.3> O_3 thin films.
東海大学の論文
1992-03-30