Tuning optoelectronic properties of SnS thin films by a kinetically controllable low temperature microwave hydrothermal method

Abstract In the polycrystalline SnS semiconductor films, the crystallite size and stoichiometry play a central role in dictating their optoelectronic properties. Most strategies to tailoring these parameters require long-time deposition methods and post-deposition thermal annealing at high temperature under inert atmosphere or sulfur vapor. Here, we report a different strategy of tuning optoelectronic properties of SnS films by controlling the kinetical parameters in a microwave-hydrothermal solution method at low temperatures (50–60 °C). The interaction between microwave radiation and the highly polar thioacetamide (TA, sulfur source) enhances local temperature in the reaction solution and permits a rapid formation of orthorhombic SnS crystallites on glass substrates. For as-deposited SnS films, a lineal dependence is observed of the film thickness, crystallite size and electrical conductivity on the TA concentration. In addition, the microstrain, Sn/S ratio and optical band gap of the films decrease with the concentration of TA, leading to the optimal values for stoichiometry and optical properties of SnS films. The ability to synthesize highly crystalline SnS thin films at high growth rates and low temperatures opens up possibilities to the fabrication of SnS-based optoelectronic devices on plastic substrates.