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

Tin disulfide (SnS 2 ) is a two-dimensional (2D) post-transition metal chalcogenide (p-TMDC) with considerable potential to compete with other benchmarked 2D-TMDC materials such as MoS 2 and WS 2 . Compared with other 2D-TMDC materials, SnS 2 has the strong advantage of being synthesized at low temperature. However, a lower synthetic temperature of SnS 2 lessens its thermal stability at high temperature. Thus, many researchers have cautiously handled SnS 2 when exposing it to high process temperature. In this paper, 2D SnS 2 thin films with and without an Al 2 O 3 passivation layer were prepared by atomic layer deposition (ALD), and post-annealing was performed under a H 2 S environment at various temperatures. SnS 2 thin film with an Al 2 O 3 passivation layer is more thermally stable at higher temperature during post-annealing than is SnS 2 thin film without an Al 2 O 3 passivation layer. Furthermore, higher temperatures used during post-annealing facilitate enhanced crystallinity of 2D SnS 2 thin films without evaporation. The enhanced crystallinity is mainly attributed to the presence of an Al 2 O 3 passivation layer that blocks evaporation of SnS 2 and enables increased processing temperature in post-annealing.