Realization of Hybrid Superconductor–Semiconductor Systems by Homoepitaxial Growth of Non-equilibrium P-doped Si(111)

To fulfill the long-term vision of reliable quantum computation, the ideal hybrid platform allows quantum information to be processed, stored and transmitted in the same materials system. Silicon can be a promising candidate for fault-tolerant hybrid quantum systems due to its multifunctionality, reliability and long coherence times. Superconducting Si could provide a viable pathway for realization of Si qubit circuits, by forming homogeneous Superconductor (SC)–Semiconductor–SC Josephson junctions. In this work, non-equilibrium p-doping of Si thin-films by homoepitaxial growth of Ga-rich Si on Si(111) is studied. Surface structure and morphology of the p-doped films were evaluated by reflection high-energy electron diffraction and atomic force microscopy. Doping levels and carrier concentrations were determined by temperature-dependent resistivity (ρ–T) measurements in van der Pauw configuration and on Hall bars. Upon increase in Ga incorporation, ρ–T characteristics of the p-doped films transitioned from insulating to quasi-reentrant superconductivity with R_min/R_N of 0.82–0.89. Based on the known theories, mechanisms and strategies to go beyond the quasi-reentrant regime will be discussed.