Understanding disorder in monolayer graphene devices with gate-defined superlattices
Year: 2024
Type: article
Abstract: Engineering superlattices (SLs)—which are spatially periodic potential landscapes for electrons—is an emerging approach for the realization of exotic properties, including superconductivity and correlated insulators, in two-dimensional materials. While moiré SL engineering has been a popular approach, nanopatterning is an attractive alternative offering control over the pattern and wavelength of the SL. However, the disorder arising in the system due to imperfect nanopatterning is seldom studied. Here, by creating a square lattice of nanoholes in the SiO2 dielectric layer using nanolithography, we study the SL potential and the disorder formed in hBN-graphene-hBN heterostructures. Specifically, we observe that while electrical transport shows distinct SL satellite peaks, the disorder of the device is significantly higher than graphene devices without any SL. We use finite-element simulations combined with a resistor network model to calculate the effects of this disorder on the transport properties of graphene. We consider three types of disorder: nanohole size variations, adjacent nanohole mergers, and nanohole vacancies. Comparing our experimental results with the model, we find that the disorder primarily originates from nanohole size variations rather than nanohole mergers in square SLs. We further confirm the validity of our model by comparing the results with quantum transport simulations. Our findings highlight the applicability of our simple framework to predict and engineer disorder in patterned SLs, specifically correlating variations in the resultant SL patterns to the observed disorder. Our combined experimental and theoretical results could serve as a valuable guide for optimizing nanofabrication processes to engineer disorder in nanopatterned SLs.
Source: Nanotechnology
Institution: Pennsylvania State University
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,165
Funders: National Science Foundation, University of Pennsylvania, Pennsylvania State University, National Institutes of Health, Materials Research Science and Engineering Center, Harvard University, Institute for Computational and Data Sciences, Pennsylvania State University, National Institute of Biomedical Imaging and Bioengineering, Division of Materials Research, Division of Electrical, Communications and Cyber Systems, Division of Engineering Education and Centers
Awards: G2515106960, Developing a Rapid, Simple-to-use Sensory Platform for Detection of Ultralow Concentration of SARS-CoV-2 Viral Particles Enabled by Electrophoretic Enhancement and Redox Cycling, G4742140246, CAREER: Tunable Graphene Microdevices for Multiplexed Detection of Biomolecules Beyond Diffusion Limit, G5426085457, I/UCRC Phase II: The Pennsylvania State University: Center for Atomically Thin Multifunctional Coatings (ATOMIC), G664466102, G8758590412, MRSEC: Center for Nanoscale Science
OpenAlex ID: W4402357725