Technology and properties of a vector hall sensor

Symmetrical four-sided ∼12-μm-high pyramids with 30°-tilted sides were revealed by the etching of semi-insulating (1 0 0) GaAs substrates in 1H3PO4:×H2O2:8H2O at ∼25 °C via sacrificial 〈0 0 1〉-oriented Ti/GaAs/AlAs (100/2000/100 nm) etching mask patterns. The pyramids, MOCVD overgrown with InGaP/AlGaAs/GaAs heterostructure pyramids, were used as the base for magnetic field vector sensors. Each sensor consisted of three Hall probes defined on the sides of a pyramid. The device processing was realized via AZ5214-E layers deposited conformally over the pyramids by draping from water surface. While the planar reference 5×5-μm2-sized Hall probes exhibited a sensitivity of ∼930 VA−1T−1 at 298 K, the sensitivity of those on the 30°-tilted facets was impossible to determine because they had a resistance of ∼100 kΩ at 298 K. Further work is necessary to optimize the InGaP/AlGaAs/GaAs heterostructure growth and dopant incorporation on the 30°-tilted pyramidal facets.