Switchable valley functionalities of an $n-n^{-}-n$ junction in 2D semiconductors

Abstract

We show that an $n-n^{-}-n$ junction in 2D semiconductors can flexibly realize two basic valleytronic functions, i.e. valley filter and valley source, with gate controlled switchability between the two. Upon carrier flux passing through the junction, the valley filter and valley source functions are enabled respectively by intra- and inter-valley scatterings, and the two functions dominate respectively at small and large band-offset between the $n$ and $n^{-}$ regions. It can be generally shown that, the valley filter effect has an angular dependent polarity and vanishes under angular integration, by the same constraint from time-reversal symmetry that leads to its absence in one-dimension. These findings are demonstrated for monolayer transition metal dichalcogenides and graphene using tight-binding calculations. We further show that junction along chiral directions can concentrate the valley pump in an angular interval largely separated from the bias direction, allowing efficient havest of valley polarization in a cross-bar device.

References in corpus (23)

• The electronic properties of graphene
• Chiral tunneling and the Klein paradox in graphene
• Valley contrasting physics in graphene: magnetic moment and topological transport
• Valley filter and valley valve in graphene
• Valley Dependent Optoelectronics from Inversion Symmetry Breaking
• Veselago Lens for Electrons: Focusing and Caustics in Graphene p-n Junctions
• Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides
• Electronic structures and theoretical modelling of two-dimensional group-VIB transition metal dichalcogenides
• Graphene valley filter using a line defect
• Valley susceptibility of an interacting two-dimensional electron system
• Valley-dependent Brewster angles and Goos-Hanchen effect in strained graphene
• Generation of pure bulk valley current in graphene
• Gate-controlled Guiding of Electrons in Graphene
• Observation of negative refraction of Dirac fermions in graphene
• Conductance calculations for quantum wires and interfaces: mode matching and Green functions
• Controlled Growth of a Line Defect in Graphene and Implications for Gate-Tunable Valley Filtering
• Spin-valley filtering in strained graphene structures with artificially induced carrier mass and spin-orbit coupling
• A controllable valley polarization in Graphene
• Quantized conductance in an AlAs 2D electron system quantum point contact
• Spin- and valley-polarized transport across line defects in monolayer MoS2
• Valley and spin pump by scattering at non-magnetic disorders
• Green${}^{\prime }$s function approach to edge states in transition metal dichalcogenides
• Theory of valley-dependent transport in graphene-based lateral quantum structures

Cited by in corpus (2)

• Valley-selective Klein tunneling through superlattice barrier in graphene
• Valley polarization and valleyresistance in monolayer transition metal dichalcogenides superlattice