Vapor phase epitaxy of cesium tin chloride perovskite films and quantum wells

Epitaxy has advanced the thin-film electronics field by enhancing many key features of semiconductors. While halide perovskites are performing well in photovoltaics, their potential for high-end electronics applications remains underexplored, and epitaxial investigations have been limited. Here we demonstrate the epitaxial growth of single-domain pseudomorphic perovskite cesium tin chloride (CsSnCl3) on metal halide (NaCl) substrates by reactive vapor phase epitaxy. An epitaxially stabilized tetragonal perovskite phase is demonstrated via a combination of in-situ and ex-situ diffraction techniques, which differs from its non-perovskite monoclinic bulk phase. Moreover, we vary growth stoichiometries to uncover the epitaxial growth of another distinct tetragonal phase (CsSn2Cl5) having markedly dissimilar lattice parameters accommodated by epitaxial rotation around the NaCl substrate. The CsSnCl3 epitaxy is also exploited to grow 2D quantum wells of CsSnCl3, resulting in clear quantum confinement in photoluminescence where we extract the effective Bohr radius of 5.2 ± 0.9 nm. This work further extends how epitaxy can be utilized for the evolution of new halide perovskite phases to extend their potential beyond photovoltaics. Halide perovskites hold promise for high-end electronics, yet their epitaxial growth remains underexplored. Here, epitaxial growth of cesium tin chloride shows a new tetragonal phase and is utilized in 2D quantum wells, showing quantum confinement effects extending the material’s applicability beyond photovoltaics.