Nano and micro Hall-effect sensors for room-temperature scanning hall probe microscopy

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 (B in). 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 similar to1.5 mum(2) with a maximum drive current I-max of similar to3 muA and B-min similar to 0.2 G/rootHz. The B-min of 1.5 mum(2) InSb Hall probes was 6 x 10(-1) G/rootHz at I-max of 100 muA. Further, 200 nm x 200 nm Bi probes yielded good RT-SHPM images of garnet films, with I-max and sensitivity of 40 muA and similar to0.80 G/rootHz, respectively. (C) 2004 Elsevier B.V. All rights reserved.