A fully integrated GaAs-based three-axis Hall magnetic sensor exploiting self-positioned strain released structures

In this work, we demonstrate a fully integrated three-axis Hall magnetic sensor by exploiting microfabrication technologies applied to a GaAs-based heterostructure. This allows us to obtain, by the same process, three mutually orthogonal sensors: an in-plane Hall sensor and two out-of-plane Hall sensors. The micromachined devices consist of a two-dimensional electron gas AlGaAs/InGaAs/GaAs multilayer which represents the sensing structure, grown on the top of an InGaAs/GaAs strained bilayer. After the release from the substrate, the strained bilayer acts as a hinge for the multilayered structure allowing the out-of-plane self-positioning of devices. Both the in-plane and out-of-plane Hall sensors show a linear response versus the magnetic field with a sensitivity for current-biased devices higher than 1000 V A-1 T-1, corresponding to an absolute sensitivity more than 0.05 V T-1 at 50 ?A. Moreover, Hall voltage measurements, as a function of the mechanical angle for both in-plane and out-of-plane sensors, demonstrate the potential of such a device for measurements of the three vector components of a magnetic field.