Long range electric and magnetic fields for the sensitivity enhancement of electronic devices : Novel ZnO contact methods and permanent magnet-based magnetic field sensors
Enhancing sensor performance is crucial for reliable electronic devices. This work explores advanced fabrication techniques for zinc oxide (ZnO) piezotronic devices and introduces a novel magnetic field sensor concept. The thesis covers the fabrication of stable solder contacts on microscopic ZnO for piezotronic applications and a new magnetic field sensor based on permanent magnets. These approaches optimize magnetoelectric sensors by improving electrical contacts, enhancing the piezotronic effect, and increasing magnetic sensitivity while reducing noise. The findings contribute to improved measurement stability, sensitivity, and noise reduction in electronic devices. A refined process enabled the production of ZnO needles, joined using an innovative soldering technique. Electrical characterization confirmed soldering as a viable method for precise Schottky or ohmic contacts. Impedance spectroscopy demonstrated how external bias influences the space charge region, affecting resistance, conductivity, and sensing. The novel magnetic field sensor relies on opposing permanent magnets, detecting external fields via cantilever deflection or oscillation. Characterization revealed a sensitivity of 2.2 kV/T and a detection limit of 46 pT/√Hz. The sensor’s minimal magnetic noise, lack of shielding or cooling requirements, and simple manufacturing process position it as a competitive alternative in the field. Overall, the developed soldering method is adaptable to various semiconductors, improving contact stability and enabling piezotronic applications, including MEMS miniaturization. The proposed magnetic field sensor, with its unique properties and optimization potential, fills a gap in current sensing technology and holds promise for energy harvesting applications.
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