[7p-C11-1~21] 17.3 Layered materials

△ [7p-C11-13] Mechanical exfoliation and chemical stability of SnS thin layers

〇Naoki Higashitarumizu¹, Hayami Kawamoto¹, Keiji Ueno², Kosuke Nagashio^1,3 (1.Tokyo Univ., 2.Saitama Univ., 3.PRESTO)

Keywords:piezoelectricity, SnS

SnS monolayer, one of the group-IV monochalcogenides (MXs), has emerged as a promising candidate for high-performance piezoelectric material. However, there is no report on exfoliation or growth of monolayers of SnS and the other MXs, which is probably owing to a strong interlayer bonding with a large ionic polarization. In this work, SnS thin layers are fabricated by using Au-meditated exfoliation. A semicovalent bond of Au–S enables the exfoliation of thin and larger SnS flakes. The Raman peaks of SnS are observed only for thick flakes >6 nm, which suggests the critical thickness of degraded SnS. One of the possible reasons for this degradation is surface oxidation in air. Although loan pair electrons in Sn enable the structural flexibility and high piezoelectric coefficient of SnS, loan pair favors oxygen bonding, resulting in the formation of oxide layer. The chemical stability is discussed with the crystal structure and the electron configuration.