Role of an Al2O3 Passivation Layer during Annealing of 2D-SnS2 Thin Films Grown by Atomic Layer Deposition

Abstract

Tin disulfide (SnS2) is a two-dimensional (2D) post-transition metal chalcogenide (p-TMDC) with considerable potential to compete with other benchmarked 2D-TMDC materials such as MoS2 and WS2. Compared with other 2D-TMDC materials, SnS2 has the strong advantage of being synthesized at low temperature. However, a lower synthetic temperature of SnS2 lessens its thermal stability at high temperature. Thus, many researchers have cautiously handled SnS2 when exposing it to high process temperature. In this paper, 2D SnS2 thin films with and without an Al2O3 passivation layer were prepared by atomic layer deposition (ALD), and post-annealing was performed under a H2S environment at various temperatures. SnS2 thin film with an Al2O3 passivation layer is more thermally stable at higher temperature during post-annealing than is SnS2 thin film without an Al2O3 passivation layer. Furthermore, higher temperatures used during post-annealing facilitate enhanced crystallinity of 2D SnS2 thin films without evaporation. The enhanced crystallinity is mainly attributed to the presence of an Al2O3 passivation layer that blocks evaporation of SnS2 and enables increased processing temperature in post-annealing.