Superconductivity in IV-VI/III-V Heterostructures:Tuning Superconductivity via Band Alignment Induced Charge Transfer

Topological superconductivity has been long sought after since it was hypothesized that this state of matter can host Majorana quasi-particles, which could potentially be used for solid-state, fault tolerant quantum computing. One proposed way of realizing this state is via the proximity effect between a superconductor and a semiconductor with strong spin-orbit splitting. In this work, we achieve superconductivity in the IV-VI material, Sn_xIn_1-xTe (SIT), which is interfaced with the III-V semiconductor, InAs_1-ySb_y (IAS). While the overall T_c of SIT decreases when interfaced with IAS, by varying the amount of Sb in the semiconducting layer, we are able to tune the transfer of charge between the two layers, which impacts the critical temperature, T_c, of this system. The Hall Effect becomes nonlinear at high field in SIT on IAS, which is not seen in the control sample without IAS. This is consistent with our hypothesis that charge transfer occurs between the two layers due to band bending. Within this work, T_c between 0.6K and 1.3K has been achieved, while without IAS T_c can exceed 3K. The realization of proximity induced topological superconductivity in this structure will thus require careful control of the band alignment between SIT and IAS, and our work demonstrates that superconductivity in SIT can be readily tuned by small changes in the charge density.