Molecular Beam Epitaxy Growth of Superconducting Sn_1-<i>x</i>In_<i>x</i>Te (0 ≤ <i>x</i> ≤ 0.67) Thin Films

Topological superconductivity has attracted increasing interest for not only its novel properties but also the possible application to quantum computing. One way to realize topological superconductivity is to induce superconducting gap in the surface states of topological insulators (TIs) by the proximity effect. To maximize the superconducting proximity effect, all-telluride based heterostructures consisting of TI (Bi,Sb)₂Te₃ and Te-based superconductor (SC) may be a promising candidate. As the first step toward TI/SC heterostructures, epitaxial growth of Te-based SC is required.
In this work, we report the thin film growth of rock-salt type SC Sn_1-xIn_xTe (SIT) by means of 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 SIT 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 may lead to the TI/SC heterostructures and interfacial topological superconductivity.