Resolving few-femtosecond electron dynamics in graphene nanoribbons with multi-terahertz scanning tunneling microscopy
Abstract
Graphene nanoribbons (GNRs) synthesized by bottom-up fabrication from molecularprecursors hold the potential for atomically precise optoelectronics. However, theinteraction between the GNRs and the underlying metal substrate, which is essential forgrowth, reduc es the characteristic timescale of electronic excitations to less than 100femtoseconds. A spacer layer can be introduced into the t unnel junction by single-GNRmanipulation at liquid helium temperatures, potentially increasing the lifetime ofphotoexcited charge carriers by decoupling the GNR from the substrate. This may bringtheir intrinsic dynamics into the view of terahertz scanning tunn eling microscopy (THz-STM). However, it will also be critical to understand the interactions between GNRs andtheir substrate if th ey are to become a platform for optoelectronics.In this project, Prof. Tyler Cocker and colleagues will expand on their investigat ion ofGNRs with ultrafast THz-STM to probe the GNR-substrate interaction on the few femtosecond timescale. Phase-stable, single-cyc le multi-THz pulses will be coupled into the setup to drive tunneling on timescales as small as 3 femtoseconds. Operating at liquid helium temperatures, GNRs will be manipulated onto sodium chloride islands of varying thickness to tune their optoelectronic proper ties. These state-of-the-art technical advances will be combined with the groups recent breakthrough in the theory of THz scanning tunneling spectroscopy to form a comprehensive picture of how the GNR-substrate interaction influences the optoelectronic response of the system.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2021
- Source ID
- N000142112682
Entities
People
- Tyler L. Cocker
Organizations
- Michigan State University
- Office of Naval Research
- United States Navy