VHPC · Optical valley Hall effect in gapped graphene for infrared and terahertz light photodetection
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2017-08-22 → 2019-08-21
- EU contribution
- €158,122
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Optical valley Hall effect in gapped graphene for infrared and terahertz light photodetection
Graphene, with ultrahigh carrier mobility and ultrafast optoelectronic signal processing ability, has great potential as a carrier of valley degree of freedom and is very promising for both fundamental research and practical application of valleytronics. Therefore, successfully manipulating valley pseudospin of electrons in graphene would greatly advance the study of valleytronics. However, in contrast to the recent progresses on Transition metal dichalcogenide monolayers, the optical and opto-electric valley physics with gapped graphene has never been experimentally studied before. More importantly, the phenomena of valley optoelectronics in gapped graphene are very different from what was studied already with MoS2 in visible light range. It includes Berry effects that are controlled by infrared and terahertz (THz) light, which are orders of magnitude stronger (due to its small gap) and also has great practical applications in photodetection in this important wavelength range with under-developed photodetectors. Our overall objectives include Identifying and quantification extremely-high valley Hall photoconductivity, Unravelling time-resolved dynamics of valley optoelectronics in graphene and Optimizing infrared and THz Berry photodetectors.
Data: CORDIS, © European Union
Project objective
Modern information processing is based on the degrees of freedom (DOF) of electrons, which are known as charge and spin. Manipulating DOF of electrons is the core function of information-processing unit such as transistor and photodetector. Finding and manipulating new DOF for electrons may open up possibility for next-generation information processing, such as quantum computing. Recently, a new DOF of electrons—valley pseudospin—was found in two dimensional (2D) hexagonal lattices, whose band structures manifest a pair of valleys at the corner of the hexagonal Brillouin zone (labeled as K and -K valley), giving rise to a valley DOF that is in close analogy to electron spin. As 2D hexagonal crystal, graphene, with ultrahigh carrier mobility and ultrafast optoelectronic signal processing ability, has great potential as carrier of valley DOF and intriguing prospect for both fundamental research and practical application of valleytronics. Therefore manipulating valley pseudospin of electrons in graphene would greatly advance the study of valleytronics. This proposal presents the first experimental study of Berry optoelectronics in gapped graphene, in particular extremely strong Valley Hall effects and Valley Hall dynamics. The implementation includes three sections. The first is to break inversion symmetry of graphene crystal by fabricating graphene/boron nitride heterostructure and dual-gate bilayer graphene device. This symmetry breaking allows the Bloch electrons in K and -K valleys to experience valley-contrasted orbital magnetic moments and Berry curvatures, which result in valley-dependent optical selection rule and valley Hall effect. This supplies us paradigm for infrared and terahertz photodetection for section two. In section three, we explore the dynamics of confining charge carriers in a specified valley, by measuring the time-resolved behaviors.
Original text from CORDIS.
Participants
- FUNDACIO INSTITUT DE CIENCIES FOTONIQUES · CastelldefelsCoordinatorSpain
Links
Data: CORDIS, © European Union