Enhancement of Magnetoresistive Sensitivity by Profiling the AlGaN/GaN Polarization for Low-Field Detection

The semiconductor-based magnetoresistive field sensors typically exhibit a parabolic response in magnetoresistance (MR) change, which results in poor sensitivity at low-field detection. In this letter, a new design is proposed for the formation of two-terminal MR sensor to provide an exceptional linear relation and enhanced sensitivity at low field. The key attribute in this design is by profiling the AlGaN/GaN polarization to seamlessly shape the conductivity of 2-dimensional electron gas (2DEG) channel, and with asymmetric contact configuration. The measured sensitivity, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {R}/\Delta {B}$ </tex-math></inline-formula>, is obtained at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 75.246~\Omega $ </tex-math></inline-formula>/mT by the fabricated prototype with the minimum detectable field of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300~\mu $ </tex-math></inline-formula>T at a power consumption of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$184~\mu $ </tex-math></inline-formula>W. It represents the highest sensitivity reported for III-V based two-terminal MR devices used for the sub-mT field detection.