Investigation of the growth of few-layer SnS thin films via atomic layer deposition on an O plasma-treated substrate.

Despite increasing interest in tin disulfide (SnS) as a two-dimensional (2D) material due to its promising electrical and optical properties, the surface treatment of silicon dioxide (SiO) substrates prior to the atomic layer deposition (ALD) deposition of SnS has not been thoroughly studied. In this paper, we prepared two types of SiO substrates with and without using an O plasma surface treatment and compared the ALD growth behavior of SnS on the SiO substrates. The hydrophilic properties of the two SiO substrates were investigated by x-ray photoelectron spectroscopy and contact angle measurements, which showed that using an O plasma surface treatment tuned the surface to be more hydrophilic. ALD-grown SnS thin films on the two different SiO substrates were characterized by x-ray diffraction, Raman spectroscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. To estimate the exact thickness of the ALD-grown SnS thin films, transmission electron microscopy was used. Our data revealed that using O plasma surface treatment increased the growth rate of the initial ALD stage. Thus, the ALD-grown SnS thin film on the SiO substrate treated with O plasma was thicker than the film grown on the non-treated SiO substrate.