This project investigates the use of novel materials specially designed for high resolution room-temperature identification of ã-rays emitted from fissile materials. This effort will enhance the state of the science and body of knowledge for highly dense, heavy element semiconductors with relatively wide energy gaps. The proposed project has the potential to be transformative in nature because it will identify new materials for sensitive ã-ray detection using a new idea for materials design based on the concept of ?dimensional reduction? of covalent frameworks. Using crystal growth techniques, we will grow and survey a variety of semiconducting compounds to validate their energy gaps and their resistivity. A minimum room temperature resistivity of ~108 Ohm-cm is required in the desired materials in order to allow for larger biases to be applied, resulting in faster carrier drift velocities and deeper depletion depths in the detection device. For the highest Z materials, the so-called Fano noise can also be substantially decreased (and thus energy resolution improved), by choosing compounds such as the chalcogenides proposed here. The materials will be characterized and tested in both crystal and device form for ã-ray detection. Theory-based materials design will depend strongly on knowledge-based optimization of the desirable properties of high Z wide gap semiconductors. The selection process and experimental approach will also rely closely on theoretical guidance. This is a close interdisciplinary collaboration between synthesis, measurement and theory involving groups with complementary skills.
