Characteristics of layered tin disulfide deposited by atomic layer deposition with H₂S annealing

Abstract

Tin disulfide (SnS₂) has attracted much attention as a two-dimensional (2D) material. A high-quality, low-temperature process for producing 2D materials is required for future electronic devices. Here, we investigate tin disulfide (SnS₂) layers deposited via atomic layer deposition (ALD) using tetrakis(dimethylamino) tin (TDMASn) as a Sn precursor and H₂S gas as a sulfur source at low temperature (150°C). The crystallinity of SnS₂ was improved by H₂S gas annealing. We carried out H₂S gas annealing at various conditions (250°C, 300°C, 350°C, and using a threestep method). Angle-resolved X-ray photoelectron spectroscopy (ARXPS) results revealed the valence state corresponding to Sn⁴⁺ and S²⁻ in the SnS₂ annealed with H₂S gas. The SnS₂ annealed with H₂S gas had a hexagonal structure, as measured via X-ray diffraction (XRD) and the clearly out-of-plane (A1g) mode in Raman spectroscopy. The crystallinity of SnS₂ was improved after H₂S annealing and was confirmed using the XRD full-width at half-maximum (FWHM). In addition, high-resolution transmission electron microscopy (HR-TEM) images indicated a clear layered structure.