Optical, structural and electrical properties of RuS 2 thin films, obtained at low temperatures by spray pyrolysis

Aqueous ruthenium (III) chloride (RuCl 3 .3H 2 O) solution (0.03 M) was sprayed on pre-heated ordinary glass substrates. Amorphous ruthenium oxide thin films were obtained, which were sulfurized under vacuum at several lower heat treatment temperatures (400, 450, 500 and 550 °C) in RTP oven. The XRD results indicated the appearance of the RuS 2 phase for all the sulfurization temperatures. The layer compositions were confirmed by EDS analysis. Monocrystalline and polycrystalline RuS 2 thin films were obtained. SEM images showed mix of morphologies (filament, particles, and clusters) with porous surfaces. High absorption coefficients were deduced. The obtained RuS 2 -thin films showed different direct band gaps (1.43, 1.80, 1.79, 1.83 eV), which make it a distinct energy conversion and storage material. The opto-electrical properties of the as obtained RuS 2 -thin films make them among the best candidats for several applications, such as low cost material for low cost solar cells, and for alkaline hydrogen evolution electrocatalysts.