Ultralow 1/f noise in epigraphene devices

We report the lowest recorded levels of 1/ f noise for graphene-based devices, at the level of S V / V 2 = S I / I 2 = 4.4 × 10 − 16 (1/Hz), measured at f = 10 Hz ( S V / V 2 = S I / I 2 < 10 − 16 1/Hz for f > 100 Hz) in large-area epitaxial graphene on silicon carbide (epigraphene) Hall sensors. This performance is made possible through the combination of high material quality, low contact resistance achieved by edge contact fabrication process, homogeneous doping, and stable passivation of the graphene layer. Our study explores the nature of 1/ f noise as a function of carrier density and device geometry and includes data from Hall sensors with device area range spanning over six orders of magnitude, with characteristic device length ranging from L = 1 μm to 1 mm. In optimized graphene Hall sensors, we demonstrate arrays to be a viable route to improve further the magnetic field detection: a simple parallel connection of two devices displays record-high magnetic field sensitivity at room temperature, with minimum detectable magnetic field levels down to B min = 9.5 nT/√Hz. The remarkable low levels of 1/ f noise observed in epigraphene devices hold immense capacity for the design and fabrication of scalable epigraphene-based sensors with exceptional performance. © 2024 Author(s). ; This work was jointly supported by the Swedish Foundation for Strategic Research (SSF) (Nos. GMT14-0077, RMA15-0024, and FFL21-0129), Chalmers Area of Advance Nano, Chalmers Area of Advance Energy, Chalmers Area of Advanced material, 2D TECH VINNOVA competence Center (Ref. 2019-00068), VINNOVA (Ref. 2020-04311 and 2021-04177), Marie Sklodowska-Curie grant QUESTech No. 766025, Knut and Alice Wallenberg Foundation (2019.0140), and the Swedish Research Council VR (Contract Nos. 2021-05252 and 2018-04962). This work was performed in part at Myfab Chalmers and Chalmers Materials Analysis Laboratory (CMAL).