Graphene-based positron charge sensor

We utilize a graphene field-effect transistor to measure back-gate charging by positrons. The device consists of an exfoliated graphene flake transferred onto hexagonal Boron Nitride, placed on a 1 cm2 substrate of 500 μm thick conducting p-Si capped by 285 nm-thick SiO2. It is placed at close proxi...

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Bibliographic Details
Published in:Applied physics letters 2018-10, Vol.113 (15)
Main Authors: Or, P., Dribin, D., Devidas, T. R., Zalic, A., Watanabe, K., Taniguchi, T., May-Tal Beck, S., Ron, G., Steinberg, H.
Format: Article
Language:English
Subjects:
Applied physics
Boron nitride
Charging
Field effect transistors
Flakes
Graphene
Layered materials
Positrons
Resistance
Semiconductor devices
Silicon dioxide
Sodium 22
Substrates
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Summary:We utilize a graphene field-effect transistor to measure back-gate charging by positrons. The device consists of an exfoliated graphene flake transferred onto hexagonal Boron Nitride, placed on a 1 cm2 substrate of 500 μm thick conducting p-Si capped by 285 nm-thick SiO2. It is placed at close proximity to a 25 μCi 22Na positron source emitting a constant flux of positrons, which during the measurement annihilate within the back-gate. We demonstrate that when the back-gate is allowed to float, the charging current of ≈20 fA causes the buildup of positive charge which capacitively couples to the graphene device and is detected as a variation in the two-terminal conductance. Furthermore, a prolonged exposure to positrons causes a shift in the graphene transport characteristics, associated with local charges at the immediate environment of the graphene flake. Our results demonstrate the utility of two-dimensional layered materials as probes for charging dynamics of positrons in solids.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5053477