Browsing by Author "Okamoto, A."

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    Nano and micro Hall-effect sensors for room-temperature scanning hall probe microscopy
    (Elsevier, 2004) Sandhu, A.; Okamoto, A.; Shibasaki, I.; Oral, Ahmet
    GaAs/AlGaAs two-dimensional electron gas (GaAs-2DEG) Hall probes are impractical for sub-micron room-temperature scanning Hall microscopy (RT-SHPM), due to surface depletion effects that limit the Hall driving current and magnetic sensitivity (Bmin). Nano and micro Hall-effect sensors were fabricated using Bi and InSb thin films and shown to be practical alternatives to GaAs-2DEG probes for high resolution RT-SHPM. The GaAs-2DEG and InSb probes were fabricated using photolithography and the Bi probes by optical and focused ion beam lithography. Surface depletion effects limited the minimum feature size of GaAs-2DEG probes to ∼1.5 μm2 with a maximum drive current Imax of ∼3 μA and Bmin∼0.2 G/Hz. The B min of 1.5 μm2 InSb Hall probes was 6×10 -3 G/Hz at Imax of 100 μA. Further, 200 nm×200 nm Bi probes yielded good RT-SHPM images of garnet films, with Imax and sensitivity of 40 μA and ∼0.80 G/Hz, respectively.
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    ItemOpen Access
    Room-temperature scanning Hall probe microscope (RT-SHPM) imaging of garnet films using new high-performance InSb sensors
    (IEEE, 2002) Oral, Ahmet; Kaval, Murat; Dede, Münir; Masuda, H.; Okamoto, A.; Shibasaki, I.; Sandhu, A.
    The room-temperature scanning Hall probe microscopy (RT-SHPM) imaging of garnet films using high-performance InSb sensors was discussed. The high-performance InSb micro-Hall sensors were fabricated by optical lithography. It was found that the room-temperature noise figure of the InSb sensors was 6-10 mG/√Hz, which was an order of magnitude better than GaAs-AlGaAs two-dimensional electron gas sensors.