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In-Substrate Imaging of Diamond–hBN FET Current via Wide-Field Quantum Diamond Microscopy
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DOI:10.1021/acsaelm.6c00194.png)
Abstract
En 中文
We demonstrate wide-field magnetic imaging of current flow in hydrogen-terminated diamond field-effect transistors (FETs) through in-substrate nitrogen-vacancy (NV) centers. Hydrogen termination of the diamond surface induces a two-dimensional hole gas (2DHG), while an ensemble of near-surface NV centers located ∼1 μm below the surface enables operando magnetic imaging of current flow with micrometer-scale spatial resolution. The FETs were electrically characterized over a range of drain–source biases, Vds = 0 to −15 V, and gate voltages, Vgs = +3 to −9 V, followed by in situ wide-field NV magnetometry during device operation. Magnetic field maps and reconstructed current-density distributions directly visualize current injection at the source–drain contacts and transport beneath the hBN-gated channel. Magnetic field maps reveal current-density variations in the channel region owing to non-uniformities or defects in the gate dielectric. In addition, we observe a pronounced enhancement of the drain current (∼600 to 900 μA) and a shift in the apparent threshold voltage during laser illumination, reflecting photo-induced changes in channel electrostatics. By correlating gate-dependent magnetic images with simultaneous electrical measurements, we directly link spatial current distributions to FET transfer characteristics, providing new insight into buried interface transport and non-uniform gating effects in the transistor channel. As the methodology is compatible with top-gated FETs, it can be used to map channel current distributions with micrometer resolution in emerging channel materials, such as 2D materials and wide-bandgap channels, and establish wide-field NV magnetometry as a powerful platform for probing charge transport in transistors and van der Waals dielectric heterostructures.
Keywords:
NV magnetometry
diamond FET
hexagonal boron nitride
current density imaging
two-dimensional hole gas
wide-field magnetic imaging
quantum sensing
Journal
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4.7
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5.0K
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1.4W
