A novel electret fabrication method has been explored using a 1.7 MV Pelletron accelerator. Also, a vibrating Kelvin probe was designed and constructed for the measurement of surface potentials. The electret formation method involved using proton beams of 2 MeV energy to both partially and completely penetrate dielectric samples with metallized back plates to create defect-induced surface potentials. These potentials would likely be more resilient than those of electrets fabricated by current popular methods because the effective charge would be deposited much deeper into the material. The potentials were monitored with a custom built Kelvin probe system. This method was worth exploring as there is currently a need for more resilient electrets in the design of energy efficient micro-electro-mechanical systems (MEMS). Currently, electrets cannot survive certain MEMS fabrication processes. Two types of samples were explored. The first were 150 um thick borosilicate glass slips with a sputter coated gold backing layer. The second were silicon substrates with a 300 nm thick SiO2 layer deposited on one side and a silver backing layer on the other. The results of this thesis suggest that this charging method is inferior to other methods when applied to 150 um thick borosilicate glass. The borosilicate glass electrets were inferior both with respect to effective surface charge and effective surface charge retention. The effective surface charges attained with the SiO2/Si samples were also lower than the lowest surface charges commonly achieved by other charging methods. The SiO2/Si samples irradiated at fluences of 10 11 and 1013 ions/cm2 showed decays comparable to those achieved by other methods as of this writing. This thesis is an overview of the design and construction of a Kelvin probe system, the aforementioned method, and a comparison of the results with the characteristics of electrets fabricated by other methods commonly used today.
|Advisor:||Whitlow, Harry J.|
|Commitee:||Morra, Gabriele, Petculescu, Andi|
|School:||University of Louisiana at Lafayette|
|School Location:||United States -- Louisiana|
|Source:||MAI 58/05M(E), Masters Abstracts International|
|Subjects:||Physics, Materials science, Particle physics|
|Keywords:||Electrets, Ion beam, Kelvin probe, MEMS, Protons, SiO2|
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