Carrier-gas assisted vapor deposition for highly tunable morphology of halide perovskite thin films

Abstract

We demonstrate carrier-gas assisted vapor deposition (CGAVD) as a promising synthesis technique for high-quality metal halide perovskite thin films. Wide tunability of film microstructure and morphology are accesible with CGAVD via the combination of several independently controllable experimental variables. Here, we examine in detail the material transport mechanisms in CGAVD and develop analytical expressions for deposition rates for the halide perovskite precursors MABr, MAI, SnBr₂, and SnI₂ as a function of experimentally tunable temperatures, pressures, and flow rates. The method is then applied to systematically control the growth of MASnBr₃ thin films via co-deposition across a range of stoichiometries and morphologies. In varying source material temperature, carrier gas flow rate, dilution gas flow rate, substrate temperature, and chamber pressure, corresponding changes are realized in the degree of crystallinity, grain orientation, and average grain size (from ∼0.001 to >0.7 µm²). Thin films of MASnI₃ and MASnBr₃ deposited using CGAVD show resistivities of 0.6 Ω cm and 7 × 10⁴ Ω cm, respectively, broadly consistent with previous reports.