[15a-A404-1~11] 17.3 Layered materials

▼ [15a-A404-6] PVD growth of AA stacking SnS through screw dislocation induced by substrate edge steps

〇(D)YihRen Chang¹, Hayami Kawamoto¹, Naoki Higashitarumizu¹, Tomonori Nishimura¹, Kosuke Nagashio¹ (1.UTokyo)

Keywords:growth

Although Tin sulfide (SnS) has been highly demanded as power generator due to its high piezoelectric coefficient comparable to PZT, its piezoelectricity is limited to the odd number layers with non-centrosymmetric structure, that is, not bulk property. So far, we have demonstrated the ferroelectricity of monolayer SnS grown on mica substrate, which guarantees its piezoelectricity as well [1]. To further improve the power generation capacity, the bulk SnS with non-centrosymmetry (AA stacking) is highly required. The key idea is screw-dislocation-assisted spiral growth, which has already been observed to result in AA stacking in MoS₂. However, in general, the growth mode on atomically flat mica substrate is the layer-by-layer growth with 2D nucleation. Here, HOPG substrate containing high density of atomic edge steps, unlike mica, is applied and these steps could work as origins for the spiral growth. In this study, screw-dislocation-assisted spiral growth is successfully demonstrated in PVD SnS. The growth mode of SnS and its crystallinity of SnS on mica as well as HOPG are analyzed and compared in detail through Raman spectrum as well as AFM images to gain the insight to obtain the piezoelectric bulk SnS.
Ref.: [1] N. Higashitarumizu, et al., JSAP Fall meeting, 19a-E308-5 (2019).