Urania-Based Direct Conversion Neutron Detectors
Abstract
Direct conversion semiconductor-based neutron detectors are an ideal concept that overcome many of the deficiencies of indirect conversion neutron detectors but have not reached viability. Because of the limited isotopes that can be used for direct conversion semiconducting-based neutron detector devices, there continues to be a struggle in achieving the fundamental leakage current and carrier mobility necessary to meet the theoretical intrinsic efficiencies for thick films. However, isotopes that undergo neutron-induced fission offer a very different class of energy deposition and solids that may be able to generate and deliver the charge and transport properties needed to realize a viable direct conversion semiconductor-based neutron detector. This project aims to study the relationship and range of electrical resistivity and electrical carrier mobility as a function of slight stoichiometric changes and grain sizes to depleted U3O8 and UO3. Prior non-systematic studies of these material systems yielded room temperature electrical resistivity values of 104 to 1011 ?-cm and electrical carrier mobilities as high as 0.54 cm2/(V-s). It is well known that slight stoichiometric changes in the urania-based systems can change the electrical carrier transport properties by two- to four-orders, depending on whether the change is toward a hyper or hypo-stoichiometry. Also, the work function of U3O8 and UO3 may be a function of stoichiometry. This will be investigated because it may impact how metal contact is made to the U3O8 or UO3 material. In order to make a good ohmic contact, there should be a good match between the work function of the metal(s) and the urania surface. Thus, this will comprise a secondary but very important goal of the project since without good electrical contacts, it will not be possible to measure electrical transport properties. Through this innovative research, the education and training of our next generation of graduate and undergraduate students in the study of device physics will be realized. This proposed effort is aimed at determining the efficacy of uranium-based semiconductor electrical carrier transport properties over a range of stoichiometries that may enable thick film and very low noise (high threshold) direct conversion semiconductor-based neutron detectors.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 26, 2016
- Source ID
- HDTRA11510072
Entities
People
- Tom Meek
Organizations
- Defense Threat Reduction Agency
- University of Tennessee