- 2D Crystals
|Title||Gate-Tunable Giant Stark Effect in Few-Layer Black Phosphorus|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||Liu, 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|
|Keywords||band-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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