Silicon Ion Irradiation for Advanced Control of Superconductivity in Tungsten Ultrathin Films

Superconducting thin films are fundamental for the advancement of quantum technologies in applications such as quantum sensing, metrology, or computing. This work demonstrates precise control over the superconducting properties of tungsten thin films deposited by standard sputtering techniques resulting from silicon ion irradiation (WSi<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub>). By varying the ion fluences, we are able to systematically modify crucial parameters such as critical temperature (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i><bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_C</b>) and room temperature resistivity. The possibility of tuning them within a single thin film metal layer anticipates that distinct functions, like wiring or active areas of sensor devices, could be selectively engineered. We report structural and functional characterizations that reveal improved morphological uniformity, atomic composition control, or robust modification of electronic properties. Also relevant, the ultrathin WSi<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> films maintain the absence of thermal hysteresis even in a very low temperature range or the ease in conventional direct probing by wire bonding. These findings support the technological approach as a scalable and versatile methodology for fabricating integrated superconducting circuits with locally-tailored characteristics, crucial for next-generation quantum sensors and processors.