Investigation of the growth of few-layer SnS2 thin films via atomic layer deposition on an O2 plasma-treated substrate.

ABSTRACT

Despite increasing interest in tin disulfide (SnS2) as a two-dimensional (2D) material due to its promising electrical and optical properties, the surface treatment of silicon dioxide (SiO2) substrates prior to the atomic layer deposition (ALD) deposition of SnS2 has not been thoroughly studied. In this paper, we prepared two types of SiO2 substrates with and without using an O2 plasma surface treatment and compared the ALD growth behavior of SnS2 on the SiO2 substrates. The hydrophilic properties of the two SiO2 substrates were investigated by x-ray photoelectron spectroscopy and contact angle measurements, which showed that using an O2 plasma surface treatment tuned the surface to be more hydrophilic. ALD-grown SnS2 thin films on the two different SiO2 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 SnS2 thin films, transmission electron microscopy was used. Our data revealed that using O2 plasma surface treatment increased the growth rate of the initial ALD stage. Thus, the ALD-grown SnS2 thin film on the SiO2 substrate treated with O2 plasma was thicker than the film grown on the non-treated SiO2 substrate.