Design, fabrication and characterization of a new magnetic sensor based on plasma hall effect

Abstract

The thesis presents a new magnetic sensor using plasma Hall effect. We propose the plasma Hall effect as a new magnetic field detection method, differentiated from the conventional semiconductor Hall effect. In plasma, charge drift velocity is in the order of $10^5~10^7$ m/s, which is more than 100 times faster than that in semiconductor, resulting in the higher magnetic field sensitivity compared to the conventional semiconductor Hall device. In the theoretical study, we develop a theoretical model of the plasma Hall sensor and have characterized the plasma motion in an electromagnetic field. Plasma Hall voltage is estimated in terms of electromagnetic field, electrode geometry, plasma discharge field and pressure. On these basis, we have designed, fabricated and characterized the neon plasma Hall sensors in the macro-scale as well as those in the micro-scale. The macro-scale plasma Hall sensor, fabricated using 2mm-diameter steel electrodes, shows a magnetic field sensitivity of 136.7±10.1mV/G with 8.43% nonlinearity at a neon pressure of 80±5 torr for a circuit gain of 15.56. The macro-scale sensor, however, shows unstable performance due to the neon pressure instability in the vacuum chamber, which motivates the research on the micro-scale plasma Hall sensor. The micro-scale plasma-Hall sensor, fabricated by electroplating and on-chip vacuum packaging processes, has 1010±㎛-wide and 36±1㎛-thick electrodes. The micro-scale sensor shows a magnetic field sensitivity of 8.87±0.18mV/G with 4.48% nonlinearity at a neon pressure of 7±1torr for a circuit gain of 5.5, maintaining stable performance for 12hours.