Synthesis of hybrid oxide/chalcogenide interfaces to explore topological crystalline insulator properties

The class of topological crystalline insulators (TCIs), including SnTe, provides new opportunities to explore topological behaviors. Surface carriers in TCIs experience the same spin-momentum locking as conventional topological insulators, but are protected by crystalline symmetry, which makes possible controlling topological states in SnTe through electric field gating. This work presents growth of SnTe thin enough to achieve topological state control on a substrate, SrTiO₃, easily integrated into field-effect devices. We grow SnTe films by co-sublimation-deposition, where a high-quality thick film is controllably thinned by elevating the substrate temperature in constant flux. X-ray diffraction and atomic force microscopy confirm SnTe films grown by this process are uniform down to 7 nm. Carrier density over a range of film thickness, extracted from Hall measurements, reveals surface-dominated transport in SnTe films less than 16 nm. Weak antilocalization (WAL) behavior observed in magnetotransport is consistent with topological conduction through these surface states, and we fit WAL to theory to extract details of the topological transport. The growth method presented here opens up future opportunities to design heterostructures to further explore topological behavior.