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Gate-Tunable Giant Stark Effect in Few-Layer Black Phosphorus

TitleGate-Tunable Giant Stark Effect in Few-Layer Black Phosphorus
Publication TypeJournal Article
Year of Publication2017
AuthorsLiu, Yanpeng, Qiu Zhizhan, Carvalho Alexandra, Bao Yang, Xu Hai, Tan Sherman J. R., Liu Wei, Neto Castro A. H., Loh Kian Ping, and Lu Jiong
JournalNano Lett.
Date Published03/2017
Keywordsband-gap, bandgap, black phosphorus, electrostatical-gating, field, giant Stark effect, graphene, hexagonal boron-nitride, modulation, quantum-confinement, scanning tunnelling microscopy, scanning-tunneling-microscopy, spectroscopy, transistors, Transport

Two-dimensional black phosphorus (BP) has sparked enormous research interest due to its high carrier mobility, layer-dependent direct bandgap and outstanding in plane anisotropic properties. BP is one of the few two-dimensional materials where it is possible to tune the bandgap over a wide energy range from the visible up to the infrared. In this article, we report the observation of a giant Stark effect in electrostatically gated few-layer BP. Using low-temperature scanning tunnelling microscopy, we observed that in few-layer BP, when electrons are injected, a monotonic reduction of the bandgap occurs. The injected electrons compensate the existing defect-induced holes and achieve up to 35.5% bandgap modulation in the light-doping regime. When probed by tunnelling spectroscopy, the local density of states in few-layer BP shows characteristic resonance features arising from layer-dependent sub band structures due to quantum confinement effects. The demonstration of an electrical gate-controlled giant Stark effect in BP paves the way to designing electro-optic modulators and photodetector devices that can be operated in a wide electromagnetic spectral range.


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