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Phase Engineering of Epitaxial Stanene on a Surface Alloy

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journal contribution
posted on 16.12.2020, 17:10 by Dechun Zhou, Heping Li, Saiyu Bu, Benwu Xin, Yixuan Jiang, Nan Si, Jiao Sun, Qingmin Ji, Han Huang, Hui Li, Tianchao Niu
Stanene is a notable two-dimensional topological insulator with a large spin–orbit-coupling-induced band gap. However, the formation of surface alloy intermediates during the epitaxial growth on noble metal substrates prevents the as-grown stanene from preserving its intrinsic electronic states. Here, we show that an intentionally prepared 3×3Au2Sn­(111) alloy surface is a suitable inert substrate for growing stanene without the further formation of a complicated surface alloy by scanning tunneling microscopy. The Sn tetramer and clover-shaped Sn pentamer are intermediates for the black-phosphorene-like Sn film at a substrate temperature of <420 K, which transforms to a blue-phosphorene-like stanene with a lattice constant of 0.50 nm above 500 K. First-principles calculations reveal that the epitaxial Sn layer exhibits a lattice registry growth mode and holds a direct energy gap of ∼0.4 eV. Furthermore, interfacial charge-transfer-induced significant Rashba splitting in its electronic structure gives it great potential in spintronic applications.

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