Submicrometer Hall Sensors for Superparamagnetic Nanoparticle Detection

Submicrometer Hall sensors, with Hall cross width of ~250 nm, were fabricated from InAs/AlSb quantum well semiconductor heterostructures. The room-temperature device characteristics were examined by experimental Hall effect and electronic noise measurements combined with analytical calculations. The noise-equivalent magnetic moment resolution of the order of 10⁴mu_B/radicHz was obtained at frequencies above ~1 kHz. We show that the devices can achieve single superparamagnetic nanoparticle detection and thus be employed in experiments involving single magnetically labeled biomolecule detection.