Local insulator-to-superconductor transition in amorphous InO$_x$ films modulated by e-beam irradiation

Abstract

We present a novel method enabling precise post-fabrication modulation of the electrical resistance in micrometer-scale regions of amorphous indium oxide (a-InO$_x$) films. By subjecting initially insulating films to an electron beam at room temperature, we demonstrate that the exposed region of the films becomes superconducting. The resultant superconducting transition temperature ($T_c$) is adjustable up to 2.8 K by changing the electron dose and accelerating voltage. This technique offers a compelling alternative to traditional a-InO$_x$ annealing methods for both fundamental investigations and practical applications. Moreover, it empowers independent adjustment of electrical properties across initially identical a-InO$_x$ samples on the same substrate, facilitating the creation of superconducting microstructures with precise $T_c$ control at the micrometer scale. Some possible mechanisms for the observed resistance modifications are discussed.