Effect of Geometry on the Frequency Limit of GaAs/AlGaAs 2-D Electron Gas (2DEG) Hall Effect Sensors

Abstract

High-frequency wideband Hall effect sensors can measure currents in power electronics that operate at higher frequencies (in the Megahertz range). We experimentally investigated the frequency limit of Hall effect sensor designs based on a 2-D electron gas (2DEG) gallium arsenide/aluminum gallium arsenide (GaAs/AlGaAs) heterostructures. For the first time, an experimental investigation into the frequency limit of a 2DEG Hall effect sensor is shown. The frequency limit is measured and compared for four GaAs/AlGaAs Hall effect sensor designs, where the Ohmic contact length (contact geometry) is varied across the four devices. By varying the geometry, the tradeoff in sensitivity and frequency limit is explored, and the underlying causes of the frequency limit from the resistance and capacitance is investigated. Current spinning, the traditional method to remove offset noise, imposes a practical frequency limit on Hall effect sensors. The actual frequency limit, without current spinning, is an order of magnitude higher. An experimental frequency limit of 46 MHz is measured for 2DEG GaAs/AlGaAs sensor.