Speaker
Description
Solid-state gamma-ray detection devices have traditionally relied on single crystal materials due to their reduced crystallographic and bulk defect density, and resultant charge transport properties. Development of new, room-temperature capable semiconductors has been ongoing for decades, and continuously experiences challenges in costly fabrication and scaling towards larger area devices. In addition, many semiconductor materials that are currently being investigated suffer from environmental degradation and have limited field application. Polycrystalline materials offer several potential benefits, both in more rapid material discovery, but also in enabling larger device areas and environmental robustness. This presentation overviews ongoing materials investigations in developing polycrystalline materials and evaluating their application as solid-state gamma-ray detectors. The underlying hypothesis of this work focuses on reducing grain boundary density and defect concentration in an effort to reduce bulk electron-hole recombination, enabling more efficient charge extraction. This hypothesis is tested in two host material systems, CsPbBr3 and emerging wide band gap oxide perovskites. Novel manufacturing processes are investigated and developed for polycrystalline CsPbBr3, with an emphasis on composition and phase control, and maximizing grain size. These microstructural trends are then linked to alpha particle and gamma-ray spectra. The manufacturing processes developed are then used to investigate new wide band gap materials, including NaTaO3. Materials processing development is directly related to microstructure refinement, and subsequent gamma-ray spectra. Initial results are promising and suggest that polycrystalline devices have thin active volumes, likely due to grain boundary recombination. Future development of materials and processes are on-going and may lead to further reductions in energy resolution and more efficient detection of high-energy photons.
