Imaging Graphene Field-Effect Transistors on Diamond Using Nitrogen-Vacancy Microscopy

Abstract

The application of imaging techniques based on ensembles of nitrogen-vacancy (NV) sensors in diamond to characterise electrical devices has been proposed, but the compatibility of NV sensing with operational gated devices remains largely unexplored. Here we fabricate graphene field-effect transistors (GFETs) directly on the diamond surface and characterise them via NV microscopy. The current density within the gated graphene is reconstructed from NV magnetometry under both mostly p-and n-type doping, but the exact doping level is found to be affected by the measurements. Additionally, we observe a surprisingly large modulation of the electric field at the diamond surface under an applied gate potential, seen in NV photoluminescence and NV electrometry measurements, suggesting a complex electrostatic response of the oxide-graphene-diamond structure. Possible solutions to mitigate these effects are discussed. arXiv:1905.12873v1 [cond-mat.mes-hall]

Magnetic resonance imaging of spin-wave transport and interference in a magnetic insulator

“…We can further increase the sensitivity by applying a stronger reference field, which decouples the NV spin from noise sources (40). Increasing the microwave drive current and reducing the NV-sample distance [for instance, by depositing a van der Waals material directly onto the diamond (41)] would further increase the detection capability.…”

Investigation of charge carrier trapping in H-terminated diamond devices

“…A 532 nm laser excited NV photoluminescence (PL) was spectrally filtered and collected on a CCD camera. Recombination kinetics at the NV are extremely sensitive to band bending [20,21]. In our devices, the NV PL intensity is proportional to the charge distribution at the diamond surface.…”

“…The NV center can exist in the NV 0 and NV − charge state so the ratio between the NV − and NV 0 population is a sensitive probe of the Fermi level position, which can be modulated by band bending with surface charges. Therefore, a negative ∆PL value corresponds to an increase in the band bending relative to its position at zero bias as the NV 0 becomes the dominate charge state [20,21]. Likewise, a positive ∆PL value indicates a decrease in the band bending relative to its position at zero bias.…”

“…The magnitude of the negative capacitance is found to be linearly dependent on the perimeter of the TiC contact/Hterminated channel interface, normalised with respect to the channel length, indicating that the origin of the negative capacitance is due to charge injection and capturing from interface states at this junction. We also exploit the optical response of the nitrogen vacancy (NV) centers incorporated into the diamond below the active device region to report on near-surface changes in band bending during normal device operation [19][20][21]. NV imaging confirms that junctions are formed at these interfaces.…”

Axon hillock currents enable single-neuron-resolved 3D reconstruction using diamond nitrogen-vacancy magnetometry

“…Methods for ultrasensitive microscale magnetic field sensing [14][15][16][17][18][19][20][21] or single-cell resolution functional magnetic resonance imaging 22,23 are being progressively developed to address this challenge. Diamond-nitrogen-vacancy centers (NVC) have emerged as a class of ultrasensitive nanoscale magnetic field detectors that function at ambient temperature [24][25][26] .…”