High-Temperature Ultrasensitive FET-Based CVD Graphene Hall Probes

Hall probes play a critical role in industrial applications such as electrical compasses, current sensors, and motion detectors; however, their performance often deteriorates at high temperatures. This study presents a magnetic-field probe with an ultrahigh sensitivity of 880 Ω/T at 150 °C, achieved using a graphene Hall bar integrated into a field-effect transistor (FET) architecture. To attain this exceptional sensitivity at elevated temperatures, careful control of doping, passivation, and manufacturing defects is essential. The doping level is optimized by adjusting the gate voltage to maintain the carrier concentration near the charge neutrality point (CNP). Further improvements in sensor response at high temperatures, as well as nearly a 2-fold increase in sensitivity at room temperature, are realized through polymer passivation of graphene. In contrast, it is demonstrated that patterning graphene into a narrower channel can increase the number of defects, which reduces the Hall probe’s sensitivity. These findings demonstrate the potential of CVD graphene as a durable and high-performance material for Hall probes in challenging environments.