GNR CONDUCTANCE · Two-tip STM conductance characteristics of individual planar graphene nanoribbon
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2021-01-01 → 2022-12-31
- EU contribution
- €196,708
- Participants
- 1
- Scheme
- MSCA-IF
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Results in brief
Two-tip STM conductance characteristics of individual planar graphene nanoribbon
Electronic conductance measurements through a single one-atom thick, few-atom wide planar graphene nanoribbon (GNR) have a lasting interest as GNR hold inherent tunable band gaps relevant to numerous technological applications. For future single-molecule based electronic circuits, the complete electronic components are supposed to be embedded inside one single molecule. Here, atomically precise metallic interconnects connected at both ends of an unperturbed GNR/molecular wire structure with a picometer precision is a difficult experimental and technical problem. To address this issue, our Marie Curie action has explored the low-temperature ultrahigh vacuum (LT-UHV) two-tip scanning tunneling microscopy and spectroscopy (STM and STS) conductance characterization approach. Within the scope of this action, atomically clean conductance characterization of a single GNR in its strictly planar configuration was proposed in a way to override (1) the unclean standard nanolithography-based device fabrication and (2) the actual curved conformation conductance measurement of a single GNR using the STM tip lifting approach. Indeed, a clear understanding of the on-surface GNR synthesis protocol, a detail characterization of the GNR electronic structure stabilization and the characterization of metallic back surface support induced electronic effects have also been achieved through this action. Along the path of this action, we have invented an original and totally UHV compatible way for the measurement of the conductance of a single GNR molecular wire in an exact planar and atomically precise surface configuration, the results of which will be published soon.
Data: CORDIS, © European Union
Project objective
I will explore intrinsic charge conductance characterization of electrically decoupled individual graphene nanoribbon (GNR) in the lateral planar configuration by using two-tip scanning tunneling microscopy (STM) approach. For this purpose, on-surface synthesized GNRs of width ~1-2 nm and length <20-100 nm on metallic Au (111) surface will be considered. A unique two-tip STM microscope, which has been standardized at the host’s lab (in CEMES-CNRS), will be used for its excellent vertical (z) stability (Δz <2 pm) of piezo scanners to control the tip-to-GNR contacts. With ultimate precision, the proposed approach reserves atomic cleanliness under ultrahigh vacuum (UHV) starting from on-surface GNR synthesis on metallic Au(111) surface till the end of two-tip STM conductance characterization. We will use intermediate atomic thin layers of insulating gap sodium chloride (NaCl) to electrically decouple GNR from the Au(111) surface during charge conductance measurements with electrically disconnected substrate (floating substrate potential). We focus on the fundamental challenges associated with the two-tip charge conductance measurements of GNR, notably, establishment of stable STM tip point contacts to the GNR. Indeed, different types of contact configurations are expected depending on the tip-to-GNR distance, such as tunneling, van der Waals, chemical and mechanical, which can be monitored by recording the jump-to-contact characteristics (tunneling current vs tip height (I-z) spectra). Conductance characteristics of GNR are investigated in tip-to-tip configuration through planar GNR, which include current-voltage (I-V), voltage dependent resistance R(V), conductance G = I/V, differential conductance (dI/dV), current decay with tip-to-GNR distance (dI/dz), etc. Overall, we are determined to provide an atomic clean approach to explore the conductance characteristics of molecular GNR (width ~1-2 nm and length <20-100 nm).
Original text from CORDIS.
Participants
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS · ParisCoordinatorFrance
Links
Data: CORDIS, © European Union