Sub-micrometer Hall probes prepared by tip-inducted local anodic oxidation

We developed a technology of room temperature sub-micrometer Hall probes. Such probes can be used to evaluate absolute values of local magnetic fields and to study sub-micrometer magnetic domain structures. The probes based on an optimized shallow InGaP/AIGaAs/GaAs heterostructure, were firstly processed by standard photolithography and wet-chemical etching, and then downsized to sub-micrometer dimensions by tip-induced local anodic oxidation. The magnetic-field resolution of the probes was evaluated. We demonstrate a 200-nm Hall probe with a magnetic-field resolution of 45 ?T/(Hz)^1/2 at 140 Hz and 4.2 K, driven by 5 ?A bias current.