Tuning the Band Structure of Zn-Doped SnS₂ Nanosheet-Based Thin Films by Atomic Layer Deposition for Photoelectric Devices

Abstract

Two-dimensional tin disulfide (SnS2) is attracting attention from researchers in various fields due to its physical, optical, and electrical properties. In addition, research suggests that SnS2 doped with various metals can be used in a wide range of applications. However, few studies of the doping process in tin sulfide thin films with various doping concentrations using atomic layer deposition (ALD) and the super-cycle method have been published. Here, we describe the deposition of pristine SnS2 using ALD and analyze crystallinity, chemistry, and optical and electrical properties of SnS2 doped with various concentrations of zinc by controlling the ratio of SnS2 and ZnS using super-cycle recipes. As the doping concentration increased, a cubic-phase ZnS layer was formed, and chemical binding energies increased, revealing an n-type doping effect. As the doping concentration increased, the transmittance of the thin film increased by up to 80.5%, and the optical band gap increased to 3.43 eV. In addition, the valence-band edge energy increased up to 2.02 eV, and n-type characteristics appeared as the doping concentration of zinc increased as determined by calculation of the electronic band structure. These zinc-doped nanoscale SnS2 materials have potential for optoelectronic applications.

Atomic layer deposition of SnS2 film on a precursor pre-treated substrate

“…The representative Raman peak was located at 314 cm −1 that corresponds to Hexagonal SnS 2 A 1g mode. [41] This A 1g mode is out-of-plane vibration of sulfur atoms which is shown in inset image of figure 2(b). The Raman peak intensity increase means that there are more molecules with the A1g vibration mode, which is equivalent to improved crystallinity.…”