Nanoscale superconductor-semiconductor hybrid devices are assembled from InAs semiconductor nanowires individually contacted by aluminum-based superconductor electrodes. Below 1 K, the high transparency of the contacts gives rise to proximity-induced superconductivity. The nanowires form superconducting weak links operating as mesoscopic Josephson junctions with electrically tunable coupling. The supercurrent can be switched on/off by a gate voltage acting on the electron density in the nanowire. A variation in gate voltage induces universal fluctuations in the normal-state conductance which are clearly correlated to critical current fluctuations. The ac Josephson effect gives rise to Shapiro steps in the voltage-current characteristic under microwave irradiation.
@article{arxiv.cond-mat/0508558,
title = {Tunable Supercurrent Through Semiconductor Nanowires},
author = {Yong-Joo Doh and Jorden A. van Dam and Aarnoud L. Roest and Erik P. A. M. Bakkers and Leo P. Kouwenhoven and Silvano De Franceschi},
journal= {arXiv preprint arXiv:cond-mat/0508558},
year = {2007}
}