Nonbolometric Infrared Detection in La_2-xSr_xCuO₄ and YBa₂Cu₃O_y Epitaxial Thin Films

Abstract

The electrical responses to infrared radiation of La 2- x Sr x CuO 4 (100) and YBa 2 Cu 3 O y (110) epitaxial thin films with relatively low T c values and J c values of 10 4 –10 5 A/cm 2 are studied using modulated laser light. These films show apparent nonbolometric responses at temperatures below the transition regions which are strongly dependent on the bias current. The difference in the observed responsivity between these high- T c materials and BaPb 1- x Bi x O 3 can be explained on the basis of nonequilibrium superconductivity.