Fabrication of nanoscale Bi Hall sensors by lift-off techniques for applications in scanning probe microscopy

H.A. Mohammed, S.J. Bending

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Abstract

Bismuth Hall effect sensors with active sizes in the range of 0.1-2 μm have been fabricated by electron beam lithography and lift-off techniques for applications in scanning Hall probe microscopy. The Hall coefficients, offset resistances and minimum detectable fields of the sensors have been systematically characterised as a function of device size. The minimum detectable field of 100 nm probes at 300 K and dc currents of 5 μA was found to be B=0.9 mT Hz with scope for up to a factor of ten reduction by using higher Hall probe currents. This is significantly lower than in similar samples fabricated by focused ion beam (FIB) milling of continuous Bi films, suggesting that the elimination of FIB damage and Ga ion incorporation through the use of lift-off techniques leads to superior figures of merit. A number of ways in which the room temperature performance of our sensors could be further improved are discussed.
Original languageEnglish
JournalSemiconductor Science and Technology
Volume29
Issue number8
DOIs
Publication statusPublished - 1 Aug 2014

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Scanning probe microscopy
Focused ion beams
microscopy
Fabrication
fabrication
scanning
Hall effect
probes
sensors
Sensors
ion beams
Bismuth
Electron beam lithography
figure of merit
bismuth
elimination
Microscopic examination
lithography
electron beams
Ions

Cite this

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abstract = "Bismuth Hall effect sensors with active sizes in the range of 0.1-2 μm have been fabricated by electron beam lithography and lift-off techniques for applications in scanning Hall probe microscopy. The Hall coefficients, offset resistances and minimum detectable fields of the sensors have been systematically characterised as a function of device size. The minimum detectable field of 100 nm probes at 300 K and dc currents of 5 μA was found to be B=0.9 mT Hz with scope for up to a factor of ten reduction by using higher Hall probe currents. This is significantly lower than in similar samples fabricated by focused ion beam (FIB) milling of continuous Bi films, suggesting that the elimination of FIB damage and Ga ion incorporation through the use of lift-off techniques leads to superior figures of merit. A number of ways in which the room temperature performance of our sensors could be further improved are discussed.",
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