Superconductivity in Ga-doped Si<i> _x </i>Ge_1−<i>x</i> alloys through ion implantation and flash-lamp annealing

Abstract Group-IV superconducting semiconductors present promising opportunities on the development of scalable hybrid platforms for quantum devices. However, achieving superconducting states in semiconductors remains challenging, particularly concerning the origin of coherent coupling and the relationship between carrier concentration and critical temperature. In this study, ion implantation and flash-lamp annealing are used to achieve hyper-doped Si x Ge 1− x alloys. We investigate the tunability of the superconducting transition temperature by adjusting the Si/Ge composition and the Ga implantation fluences. As the Si concentration in Si x Ge 1− x increases, while maintaining identical doping fluences, the critical temperature is reduced from 550 mK to 40 mK. This is due to the lower solubility of Ga in Si than in Ge. Furthermore, as the Ga fluence decreases, the critical temperature is also reduced from 550 mK to 80 mK. We establish a qualitative correlation between critical temperature and free-hole concentration, which can be tuned by varying the Ga implantation fluence and the Si x Ge 1−x alloy composition.