Perovskite Polycrystalline Direct Radation Detectors

Abstract

This thesis discusses the interaction of radiation with matter and the characterisation of advanced radiation detectors, focusing on the use of perovskite materials, specifically FAPbBr3 polycrystal- line, in the field of X-ray detection. The research begins with a comprehensive review of the main principles of radiation interaction with matter, including X-ray interactions such as Compton scat- tering, the photoelectric effect, and Rayleigh scattering. Basic concepts in radiation dosimetry and charge carrier transport in semiconductor materials are also discussed, providing a foundation for understanding the behaviour of semiconductor radiation detectors. The properties and synthesis of perovskite materials are examined, discussing various methods of synthesising polycrystalline perovskite materials, such as inverse temperature crystallisation, low-temperature crystallisation, and heating-assisted solvent evaporation. Different techniques to enhance perovskite detector per- formance, such as hot pressing, surface passivation, and mixing 2D and 3D perovskite structures, are also discussed. The experimental methodology for fabricating and characterising FAPbBr3 detectors is detailed, including FAPbBr3 synthesis, grinding methods to create powder, device fab- rication, and gold contact deposition. Different characterisation techniques were employed, such as photoluminescence spectroscopy, scanning electron microscopy, X-ray diffraction, and atomic force microscopy, to analyse FAPbBr3 properties and device performance. Significant findings on optimising the performance of FAPbBr3 pellets in the radiation detection field are presented, focus- ing on the impact of different pressures, grinding methods, environmental impact, annealing, and hot-pressing impact. Key performance evaluations include electrical resistivity and behaviour, pho- toluminescence properties, and X-ray sensitivity. The impact of lead acetate addition to FAPbBr3 during fabrication and the application of guard rings to enhance device performance are also ex- plored. The thesis concludes with a discussion of the key findings, limitations, and potential future studies to develop and improve the performance of radiation detection. The project demonstrates the promising potential of FAPbBr3 devices for advanced X-ray detection applications, highlighting areas of further study and research to optimise the performance of high-performance radiation detectors. After conducting the research, it has been found that the ideal thickness for FAPbBr3 pellets for radiation detection is 1 mm. A pressing time of 5 minutes and applying higher pressures resulted in better outcomes. Annealing significantly improved the overall detector quality, enhancing sensitivity. Additionally, including lead acetate helped decrease dark current, further optimising the device’s performance for efficient radiation detection. These findings provide a clear pathway for creating high-performance FAPbBr3-based radiation detectors.