A theoretical investigation on multilayer silicon nanoribbons

•Multilayer silicon nanoribbons are investigated theoretically.•The bare nanoribbons are metallic when the number of layer is no less than three.•Edge- and surface hydrogen-passivation cause metal-semiconductor transition.•The transition is explained with frontier wavefunctions.•The full hydrogen-passivated nanoribbon has carrier mobilities of 103 cm2 V−1 s−1.

Multilayer silicon nanoribbons constructed with an armchair silicene nanoribbon are investigated based on density functional theory calculations. The bare nanoribbons are metallic except for the mono- or double-layer samples. The partially occupied frontier bands are contributed by near-degenerate surface and edge states. Edge-hydrogen atoms passivate the edge states and full hydrogenation causes a metal-semiconductor transition. These are all explained using frontier wavefunctions. A six-layer full hydrogen-passivated silicon nanoribbon has a band gap larger than that of bulk silicon, and its hole and electron mobilities are also on the order of 103 cm2 V−1 s−1, implying potential application in small-size logic devices.

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