Periodic Reporting for period 1 - atoGRAPH (Near-Infrared Optoelectronic Devices with Atomically Controlled Graphene Nanostructures)
Periodo di rendicontazione: 2020-02-10 al 2022-02-09
Plasmons, light-induced collective excitations of electrons, are the pivotal strategy to integrate electronics and optics at the nanoscale enabling single-molecule detection, improved photovoltaics, nanoscale photometry, cancer therapy, or nonlinear optics. Plasmon properties offer sub-wavelength optical confinement for enhanced imaging resolution and huge optical enhancements by strong light-matter interaction at nanostructures for colour generation. More interestingly, two dimensional (2D) graphene-plasmons are electrically tunable by electrostatic doping, enabling order-unity changes in absorption and tunable excitation plasmon energies. Additionally, the graphene’s high mobility extends its application to ultrafast light modulation up to 100s GHz commutation rates. However, graphene plasmons have been observed at mid-infrared wavelengths, which are far from the near-infrared (NIR) telecom range. To further tune graphene-plasmons to higher frequencies is necessary to open a bandgap by confining the lateral size (D), since the frequency scales as square root of (E_Fermi/D). Therefore, reaching the telecommunication frequency regime (E_fermi approximately 1 eV) requires a lateral size D reduction below 5 nm, which is beyond the state-of-art of top-down lithography.
Interestingly, covalent self-assembly of graphene-like building blocks such as polycyclic aromatic hydrocarbons render atomically precise 1-3 nm-wide graphene nanoribbons (GNR) by controlling sequential reactions on catalytic substrates. The GNR quantum confinement shifts graphene plasmons to the visible and near-infrared (vis-NIR). However, GNRs are rather short (~30 nm) and randomly distributed on the surface. To date, little effort has been directed to control their size and the overall morphology of the ensemble, setting a barrier for the implementation of GNRs on actual devices. As a solution, we propose two-dimensional (2D) nanoporous graphene (NPG) consisting in covalently bonded parallel arrays of ultra-long GNRs (>200 nm) featuring nanopores of 0.4-0.9 nm. Indeed, the theoretical optical response of NPG reveals a remarkable change in absorption at vis-NIR peaks by increasing the doping level to 1 eV, just at the telecom range. Therefore, the overall objective is to explore the feasibility of fabricating gate-modulated optoelectronic devices based on atomically precise graphene nanostructures, as a new venue to expand graphene into the vis-NIR region.
Interestingly, covalent self-assembly of graphene-like building blocks such as polycyclic aromatic hydrocarbons render atomically precise 1-3 nm-wide graphene nanoribbons (GNR) by controlling sequential reactions on catalytic substrates. The GNR quantum confinement shifts graphene plasmons to the visible and near-infrared (vis-NIR). However, GNRs are rather short (~30 nm) and randomly distributed on the surface. To date, little effort has been directed to control their size and the overall morphology of the ensemble, setting a barrier for the implementation of GNRs on actual devices. As a solution, we propose two-dimensional (2D) nanoporous graphene (NPG) consisting in covalently bonded parallel arrays of ultra-long GNRs (>200 nm) featuring nanopores of 0.4-0.9 nm. Indeed, the theoretical optical response of NPG reveals a remarkable change in absorption at vis-NIR peaks by increasing the doping level to 1 eV, just at the telecom range. Therefore, the overall objective is to explore the feasibility of fabricating gate-modulated optoelectronic devices based on atomically precise graphene nanostructures, as a new venue to expand graphene into the vis-NIR region.
To accomplish our first goal, we synthesize self-ordered parallel arrays of GNR by guiding molecular precursor along nanostructured Au(111) catalytic substrate via a bottom-up approach. Precise control of the reaction temperature allows inter-ribbon interactions to covalently bond GNRs as nanoporous graphene (NPG)- The atomic and electronic structure is , which are evidenced by tunnelling microscopy. Furthermore, the electronic structure of as-synthesized GNR and NPG is resolved by tunnelling spectroscopy, revealing 1 eV and 0.88 eV energy gap, respectively, just at the telecom range.
The results have been accepted in three conferences and the state-of-art of low dimensional materials optolectronic devices has been compiled in an invited review. Moreover, the NPG superlattice has triggered a new collaboration (QEE2DUP project) with the quantum nano-optoelectronic group directed by F. Koppens, to confine 2D quantum emitters by NPG electrostatic confinement, leading to the Barcelona Institute for Science and Technology (BIST) award 2021 and aligning us with European Quantum Flagship. Moreover, the PI enabled that Prof. Aitor Mugarza hired a postdoctoral fellow through Beatriu de Pinós, that is a Catalan postdoctoral call funded through MSCA COFUND Grant Agreement nº 801370.
The results have been accepted in three conferences and the state-of-art of low dimensional materials optolectronic devices has been compiled in an invited review. Moreover, the NPG superlattice has triggered a new collaboration (QEE2DUP project) with the quantum nano-optoelectronic group directed by F. Koppens, to confine 2D quantum emitters by NPG electrostatic confinement, leading to the Barcelona Institute for Science and Technology (BIST) award 2021 and aligning us with European Quantum Flagship. Moreover, the PI enabled that Prof. Aitor Mugarza hired a postdoctoral fellow through Beatriu de Pinós, that is a Catalan postdoctoral call funded through MSCA COFUND Grant Agreement nº 801370.
The atoGRAPH project gives insights on the daunting task of building optoelectronic devices based on atomically precise graphene nanostructures. For example, the European Roadmap of Graphene highlights the need of novel bottom-up molecular approaches that overcome the limitations of top-down patterning strategies. As an innovative strategy, our chemical synthetic route enables atomically precise parallel arrays of ultra-long (>200 nm) GNRs to enable the intrusion of GNR into the market, a primary goal of the H2020 Programme. Indeed, the team has protected the graphene-based nanomaterial and its applications through the European patent EP18382088.5. The atoGRAPH has been also embedded with the European Interreg POCTEFA project Trans-Pyrenean Node for Scientific Instrumentation to scale up the production of large area NPG in a new synthetic chamber, hence pushing up the readiness level of our technology from the proof-of-concept to pre-industrial prototypes. The technological impact of NPG has already attracted the interest of several technological research centres and industrial agents. Indeed, the atoGRAPH collaborates with Nanofrazor, the first commercial thermal scanning probe lithography tool, for nanopatterning irradiation-free contacts with great implications in device nano-fabrication. The atoGRAPH is also collaborating with Graphenea, a leading company in high-quality graphene, to develop extremely sensitive sensors down to parts per billion based on our graphene-based nano-architectures, which have served to develop a new proposal to compete in the 5 billion dollar sensor market predicted for 2025.
The fast photosensing capabilities of the atoGRAPH proof-of-concept represents also an extraordinary opportunity to boost the speed of the next-generation of 6G communications, and emphasize the importance of promoting the highest potentials of graphene to have a major impact on European industrial competitiveness, as spotlighted by the European Graphene Flagship Director. Accordingly, the atoGRAPH project has initiated a collaboration with F. Koppens, a work package leader of the Graphene Flagship, to electrostatically confine two-dimensional quantum emitters at the 0.4-0.9 nm NPG pores of NPG. Indeed, the PI´s proposal has won the Barcelona Institute for Science and Technology (BIST) award 2021, highlighting its ground-breaking impact in quantum optical communications. Furthermore, PI has worked in the EU funded 2D-SIPC consortium with the most relevant European partners in the field, to build optical quantum platforms based on two-dimensional materials. Therefore, the atoGRAPH projects is expanding the horizon of atomically-precise GNRs towards quantum optical communications, which is among the most sought-after achievements by the EU Quantum Flagship, thus opening access to the €1 billion fund to support our zeal for quantum technology applications.
The fast photosensing capabilities of the atoGRAPH proof-of-concept represents also an extraordinary opportunity to boost the speed of the next-generation of 6G communications, and emphasize the importance of promoting the highest potentials of graphene to have a major impact on European industrial competitiveness, as spotlighted by the European Graphene Flagship Director. Accordingly, the atoGRAPH project has initiated a collaboration with F. Koppens, a work package leader of the Graphene Flagship, to electrostatically confine two-dimensional quantum emitters at the 0.4-0.9 nm NPG pores of NPG. Indeed, the PI´s proposal has won the Barcelona Institute for Science and Technology (BIST) award 2021, highlighting its ground-breaking impact in quantum optical communications. Furthermore, PI has worked in the EU funded 2D-SIPC consortium with the most relevant European partners in the field, to build optical quantum platforms based on two-dimensional materials. Therefore, the atoGRAPH projects is expanding the horizon of atomically-precise GNRs towards quantum optical communications, which is among the most sought-after achievements by the EU Quantum Flagship, thus opening access to the €1 billion fund to support our zeal for quantum technology applications.