Radiation Effects on Lithium Indium Diselenide Semiconductors as Neutron Imaging Detectors

The studies presented in this work aim to improve upon the knowledge base of lithium indium diselenide (LISe) semiconductors to understand how the material behaves in high radiation environments and refine the process of turning it into a neutron detector. LISe has great potential as neutron imaging detector because of the high neutron absorption efficiency of its enriched ⁶Li component and its ability to discriminate between gamma-rays and neutrons. Its ability to remain functional after being irradiated with large amounts of neutron fluence has been tested and the change in its electro-optical properties with relation to fluence has been documented. The characterization methods employed in this study include: UV-Vis, Fourier Transform – Infrared Red characterization, radioluminescence, Raman shift, photoluminescence, time resolved photoluminescence, gamma-ray radiation response, and neutron radiation response. These methods have been applied to a set of 10 LISe samples, of which 5 were irradiated to 1 × 10¹² neutrons/cm², 1 × 10¹³ neutrons/cm², 1 × 10¹⁴ neutrons/cm², 1 × 10¹⁵ neutrons/cm², and 1 × 10¹⁶ neutrons/cm². The properties of the samples and their radiation response did not change linearly with respect to fluence and seem to be sensitive to neutrons up through fluences of 1 × 10¹⁴ neutrons/cm². Several characteristics of LISe that appeared in the literature were identified here as well as several that were expected to appear based on theoretical analyses. The LISe samples processed for use as neutron imaging detectors during the course of this work have not been tested at the time of writing but the refined procedure has achieved more consistent results. Overall, this effort has contributed to a better understanding of how LISe would function in real world high radiation environments and assisted in processing more samples for proto-type detector testing.