InAs quantum well Hall devices for room-temperature detection of single magnetic biomolecular labels

Abstract

Hall sensors with cross width of ∼1μm were fabricated from InAs∕AlSb quantum well semiconductor heterostructures containing two-dimensional electron gas. The room-temperature device characteristics were examined by Hall effect and electronic noise measurements along with analytical calculations. In the low-frequency range, from 20Hzto1.6kHz, the noise-equivalent magnetic field resolution was found to be limited by 1∕f and generation-recombination noise from 22to3.5μT∕Hz. The corresponding noise-equivalent magnetic moment resolution reached 106μB∕Hz at ∼700Hz and was even lower at higher frequencies. Using a phase-sensitive measurement technique, detection of a single 1.2μm diameter bead, suitable for biological applications, was achieved with a signal to noise ratio of ∼33.3dB, as well as detection of six 250nm beads with a signal to noise of ∼2.3dB per bead. The work demonstrates the efficacy of InAs quantum well Hall devices for application in high sensitivity detection of single magnetic biomolecular labels.