A deflected edge emission field effect transistor (DEEFET), a hybrid solid-state and vacuum microelectronics device, was constructed to measure magnetic fields. The operating principle of the device as a magnetic sensor is that when a magnetic field is not present, the emitted electrons move to the anode with straight lines, and an equivalent current is received in both anode electrodes. When an external magnetic field is applied to this device, the emitted electrons deviate from the initial trajectory due to the Lorentz force, which causes imbalance in the anode current between the two neighboring anodes. Therefore, the density and direction of the external magnetic field can be detected by measuring the anode current imbalance.; Compared with conventional semiconductor magnetic sensors such as Hall devices and magnetoresistors, the DEEFET device has many advantages: higher magnetic sensitivity, greater tolerance to high temperature and thermal radiation environments, and wideband frequency response (cutoff frequency: ∼500kHz). Analytical modeling was performed to determine the device structure leading to low turn-on voltage, high emission current, and high magnetic sensitivity. Then computer simulation was carried out to predict device performance from that structure and to compare the theoretical values and experimental ones. A unique device structure was designed, employing a gate electrode and triangular-shaped anodes. Electron beam lithography (EBL) with nano scale minimum picture size was used to create a sharp tip and for precise control of the device dimensions. New device fabrication and processing procedures were created and implemented. During device characterization, excellent and stable field emission currents were observed around an anode bias of 40V. These superior field emission characteristics can be attributed to an increased field enhancement effect, which is related to the sharp tip and high aspect ratio, and the tip material's stability against foreign contaminants. The DEEFET turn-on voltage is reasonable for utilizing the device to measure current flowing through a conductor. A gate electrode was employed to further reduce the turn-on voltage. As the gate potential is increased, lower turn-on voltage (around 30V) and higher field emission current were observed, because the gate potential increased the electric field around the emitter tip. When forward and reverse magnetic field were applied to the device, anode current imbalance was observed due to electron deflection by the Lorentz force. The calculated magnetic sensitivity was 83%/Tesla for the forward magnetic field of 0.5 Tesla and 42%/Tesla for the reverse magnetic field. These magnetic sensitivities are 5 or 6 times higher than those from conventional solid-state magnetic sensors.
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