Determining the number of graphene nanoribbons in dual-gate field-effect transistors
Zhang J., Borin Barin G., Furrer R., Du C. Z., Wang X. Y., Müllen K., Ruffieux P, Fasel R, Calame M & Perrin M. L.
Nano Letters. (2023).
Abstract
Bottom-up synthesized graphene nanoribbons (GNRs) are increasingly attracting interest due to their atomically controlled structure and customizable physical properties. In recent years, a range of GNR-based field-effect transistors (FETs) has been fabricated, with several demonstrating quantum-dot (QD) behavior at cryogenic temperatures. However, understanding the relationship between the cryogenic charge-transport characteristics and the number of the GNRs in the device is challenging, as the length and location of the GNRs in the junction are not precisely controlled. Here, we present a methodology based on a dual-gate FET that allows us to identify different scenarios, such as single GNRs, double or multiple GNRs in parallel, and a single GNR interacting with charge traps. Our dual-gate FET architecture therefore offers a quantitative approach for comprehending charge transport in atomically precise GNRs.
Double quantum dots in atomically-precise graphene nanoribbons
Zhang J., Liu Q., Borin Barin G., Chen P., Muellen K., Ruffieux P., Fasel R., Zhang J., Calame M. and Perrin M.
{Materials for Quantum Technology 2023
Abstract
Fabrication of freestanding photonic devices combining polymer films with microfabrication techniques and 3D printing
Hack, E., Shorubalko, I., Graf, J., Zolliker, P., & Mavrona, E.
Optics Express, 31(18), 29968-29974. (2023).
Abstract
We report a technological concept for freestanding photonic elements based on metamaterials fabricated on polymer films by clean-room processes and framed using 3D printing. A spin-coated cyclic olefin copolymer (TOPAS) of variable thickness down to one micrometer was used as the substrate onto which metamaterials were fabricated using optical lithography. We demonstrate the possibility of applying a second TOPAS layer to protect the device or to allow for stacking another metamaterial layer. To obtain freestanding elements, frames were 3D printed directly on top of the metamaterial before lift-off from the carrier wafer. This ensured maintaining the flatness of the elements. Both the cleanroom process and the 3D printing enabled the design and manufacturing of elements in different sizes and shapes, e.g., to adapt to specific experimental set-ups and holder geometries or to be compatible with standard optical mounts. While TOPAS is transparent for wavelengths from UV to the far infrared, except for a few infrared absorption lines, we illustrate the concept with the simulation and manufacturing of THz band-pass filters. The performance of the fabricated filters was assessed using THz time-domain spectroscopy. The process is scalable to other wavelength ranges and has the potential for upscaling in manufacturing.