Molecular beam epitaxy of superconducting Sn_1-<i>x</i>In<i>_x</i>Te (0 ≤ <i>x</i> ≤ 0.66) thin films

Topological superconductivity has attracted increasing interest these days. A superconductor Sn_1-xIn_xTe, which is derived from a topological crystalline insulator SnTe, is one such candidate whose topological property has been vigorously debated mainly in bulk crystals. Sn_1-xIn_xTe in a thin-film form compatible with the device fabrication would provide an intriguing platform to explore topological superconductivity. Moreover, thin films of Sn_1-xIn_xTe would also be an useful superconductor to realize interfacial topological superconductivity by fabricating heterostructures with a topological insulator such as (Bi,Sb)₂Te₃.
In this work, we report the thin film growth of Sn_1-xIn_xTe by molecular beam epitaxy. By finely tuning the amount of Te supply especially in the high-doping region, we have achieved In-doping up to x = 0.66, which exceeds bulk solubility limit under ambient pressure x ~ 0.5. In the transport measurements, we have observed superconductivity in Sn_1-xIn_xTe thin films, and T_c shows dome-shaped dependence on x with the highest T_c = 4.25 K at x = 0.55. Our result suggests that thin films can be a useful platform to explore topological superconductivity in Sn_1-xIn_xTe or Sn_1-xIn_xTe-based heterostructures.