Preparation and growth of sulfide heterostructure thin films from designed precursors

Design of chalcogenide heterostructures has enabled access to a remarkable range of material properties occuring as a result of structural flexibility at the nanoscale. A powerful approach to generating heterostructures involves the preparation of an amorphous precursor film designed to mimic the desired end product. While this has been highly successful in generating selenium-based heterostructures with novel properties, sulfur-based compounds have remained unexplored. Here we present the first crystalline sulfide heterostructure prepared using this precursor approach, forming superlattices with a tunable number of SnS layers sandwiched between monolayers of TaS₂. Structural measurements confirm film crystallinity and overall film smoothness, and architecture is confirmed by high resolution TEM and EDS that resolves atomically precise sequencing of SnS and TaS₂ layers. Formation mechanisms are assessed in terms of mobility of precursor elements upon heating. A path towards sulfide heterostructures with adjustable stacking orders allows the development of materials with precisely tuned properties that utilize phenomenon inherent in constituent compounds; such materials are promising for applications in advanced electronics.