Advanced microstructured semiconductor neutron detectors: design, fabrication, and performance

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Show simple item record Bellinger, Steven Lawrence 2012-10-22T14:28:39Z 2012-10-22T14:28:39Z 2012-10-22
dc.description.abstract The microstructured semiconductor neutron detector (MSND) was investigated and previous designs were improved and optimized. In the present work, fabrication techniques have been refined and improved to produce three-dimensional microstructured semiconductor neutron detectors with reduced leakage current, reduced capacitance, highly anisotropic deep etched trenches, and increased signal-to-noise ratios. As a result of these improvements, new MSND detection systems function with better gamma-ray discrimination and are easier to fabricate than previous designs. In addition to the microstructured diode fabrication improvement, a superior batch processing backfill-method for 6LiF neutron reactive material, resulting in a nearly-solid backfill, was developed. This method incorporates a LiF nano-sizing process and a centrifugal batch process for backfilling the nanoparticle LiF material. To better transition the MSND detector to commercialization, the fabrication process was studied and enhanced to better facilitate low cost and batch process MSND production. The research and development of the MSND technology described in this work includes fabrication of variant microstructured diode designs, which have been simulated through MSND physics models to predict performance and neutron detection efficiency, and testing the operational performance of these designs in regards to neutron detection efficiency, gamma-ray rejection, and silicon fabrication methodology. The highest thermal-neutron detection efficiency reported to date for a solid-state semiconductor detector is presented in this work. MSNDs show excellent neutron to gamma-ray (n/γ) rejection ratios, which are on the order of 106, without significant loss in thermal-neutron detection efficiency. Individually, the MSND is intrinsically highly sensitive to thermal neutrons, but not extrinsically sensitive because of their small size. To improve upon this, individual MSNDs were tiled together into a 6x6-element array on a single silicon chip. Individual elements of the array were tested for thermal-neutron detection efficiency and for the n/γ reject ratio. Overall, because of the inadequacies and costs of other neutron detection systems, the MSND is the premier technology for many neutron detection applications. en_US
dc.language.iso en_US en_US
dc.publisher Kansas State University en
dc.subject Microstructured semiconductor neutron detector en_US
dc.subject Microstructured diode en_US
dc.subject Helium-3 replacement en_US
dc.subject Neutron detector en_US
dc.subject Solid state neutron detector en_US
dc.subject Semiconductor neutron detector en_US
dc.title Advanced microstructured semiconductor neutron detectors: design, fabrication, and performance en_US
dc.type Dissertation en_US Doctor of Philosophy en_US
dc.description.level Doctoral en_US
dc.description.department Department of Mechanical and Nuclear Engineering en_US
dc.description.advisor Douglas S. McGregor en_US
dc.subject.umi Electrical Engineering (0544) en_US
dc.subject.umi Nuclear Engineering (0552) en_US
dc.subject.umi Physics (0605) en_US 2011 en_US December en_US

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