Effect of hydrogen sulfide concentration on two-dimensional SnS<sub>2</sub> film by atomic layer deposition in annealing process

Abstract

Two-dimensional materials are widely studied due to its unique physical, optical, electrical properties, and good compatibility with various synthesis methods. And among the many fabrication methods, tin disulfide (SnS2) material, a two-dimensional (2D) material that can be achieved with accurate thickness control using atomic layer deposition (ALD), high uniformity and conformality even at low process temperatures is attracting attention. However, since the crystallinity of the thin film is low at a low process temperature, various post-annealing methods are being studied to compensate for film quality. In this work, we compared the crystal structures, chemical binding energies, and electrical properties of the thin films by post-annealing SnS2 thin films according to the hydrogen sulfide concentrations of 4.00% and 99.99% in the hydrogen sulfide atmospheres. The crystallinity, grain size, and carrier concentrations of the SnS2 thin film were the highest at a post-annealing temperature of 350 degrees C at a hydrogen sulfide concentration of 99.99%, and the chemical binding energies also corresponded with the standard Sn4+ states, forming a pure 2D-hexagonal SnS2 phase. In addition, SnS2 thin films deposited via ALD showed high uniformity and conformality in large-scale wafers and trench structure wafers.