Electric-field tuning of the superconductor-insulator transition in granular Al films

Wenhao Wu, Louisiana State University
P. W. Adams, Louisiana State University


The superresistive phase of thin granular films near the superconductor-insulator transition is believed to result from the suppression of Josephson tunneling by the large charging energy, Ec, of the grains. Our ac I-V studies of granular Al films suggest that a small dc bias voltage can be used to overcome this Coulomb barrier and to recover Josephson tunneling. This bias, in fact, drives a critically disordered film from the superresistive phase to a quasisuperconducting phase. © 1994 The American Physical Society.