Bismuth Hall probes: Preparation, properties and application

Bismuth Hall probes with an active area in the µm² and sub-µm² (down to (100 × 100) nm²) range have been fabricated on SiO₂/Si substrates. The structural and electrical properties of Bi films with a thickness of 20–90 nm were investigated. Critical values of the structural characteristics, at which the film resistivity dependences undergo a distinct change were found. The transition to low resistivity, good crystallinity and high degree of texturing were observed at a film thickness of 65 nm. The potential use of the Bi Hall sensor as a swell sensor for monitoring the swelling of stimuli-sensitive hydrogels was demonstrated.