Tuning the electronic and optical properties of monolayer and multilayer phosphorene

Date: 12 March 2019

Venue: University of Antwerp - Campus Groenenborger - Room U.244 - Groenenborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM - 5:00 PM

Organization / co-organization: CMT

Short description: CMT Lecture presented by Longlong Li, CMT



Tuning the electronic and optical properties of monolayer and multilayer phosphorene

Abstract:

Straining, gating and twisting can be used to tune the bandgap and the electron and hole mass of black phosphorus (BP). Due to the strong anisotropic atomic structure of BP, its electronic conductivity and optical response are sensitive to the magnitude and the orientation of the applied strain. The number of stacking layers and the type of stacking of BP layers influences its electronic and optical properties. Different stacking types result in similar energetics while the size of the band gap and the optical response of bilayer turn out to be sensitive to the number of layers, the stacking type and the applied perpendicular electric field. We found that the twist angle in combination with an appropriate gate voltage is a novel way to tune the electronic and optical properties of bilayer phosphorus and it gives us a new degree of freedom to engineer the properties of BP based devices. It is known that applying a gate electric field to a multilayer structure induces a charge redistribution over the stacking layers, which in turn produces an internal electric field that counteracts the externally applied one, and thereby result in a reduced (effective) field applied to the structure. We showed that the field-induced charge screening has a significant impact on the electronic and optical properties of gated multilayer BP. The effect of charge screening becomes more pronounced with increasing number of phosphorene layers. We found (i) charge density/screening anomalies and screening-induced band-gap reduction and (ii) that the field modulation of linear dichroism and Faraday rotation is strongly affected by the field-induced charge screening.



Link: http://cmt.uantwerpen.be