Micro-Hall devices for magnetic, electric and photo-detection

Multifunctional mesoscopic sensors capable of detecting local magnetic ($B)$, electric ($E)$, and optical fields can greatly facilitate image capture in nano-arrays that address a multitude of disciplines. The use of micro-Hall devices as $B$-field sensors [1] and, more recently as $E$-field sensors [2] is well established. Here we report the real-space voltage response of InSb/AlInSb micro-Hall devices to not only local $E$-, and $B$-fields but also to photo-excitation using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local $E$-fields. Our experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. At room temperature, samples exhibit a magnetic sensitivity of \textgreater 500 nT/$\surd $Hz, an optical noise equivalent power of \textgreater 20 pW/$\surd $Hz ($\lambda \quad =$ 635 nm) comparable to commercial photoconductive detectors, and charge sensitivity of \textgreater 0.04 $e$/$\surd $Hz comparable to that of single electron transistors. [1] Boero, G.; Demierre, M.; Besse, P. A.; Popovic, R. S. \textit{Sensors and Actuators A-Physical} \textbf{2003,} \textit{106} (1-3), 314-320. [2] Barbolina, I. I. et al. \textit{Applied Physics Letters} \textbf{2006,} \textit{88} (1), 013901.