Investigation of the I–V characteristics asymmetry in semiconducting Y-Ba-Cu-O diodes

Abstract

Thin films of YBCO oxygen-deficient superconductor were used to manufacture asymmetric microdiodes and investigate their asymmetric nonlinear current–voltage (I–V) dependences at temperatures T > Tc, where Tc is the temperature of the onset of superconductivity in the material. The diodes are based on being asymmetrically narrowed down to a 10-um-wide–neck mesa exhibit voltage asymmetry depending on the current bias conditions, the mesa’s temperature, and a residual oxygen content in its neck region. The intrinsic electric field in the biased diode causes free-carrier drift velocity saturation, initiated in the mesa’s neck and following its asymmetric enlarging toward the mesa’s electrodes depending on the biasing pulsed-current amplitude, polarity, and rise time/fall time of the pulse’s leading/trailing edges. The variation of the I–V characteristics asymmetry has been associated with change in the mesa’s electric resistivity, affected by the electric field’s asymmetric distribution in the YBCO mesa. It has been also demonstrated that our asymmetric diodes with the reduced oxygen content are sensitive detectors of microwave radiation.