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Formamidinium lead bromide (FAPbBr₃) single crystal perovskites have recently emerged as a key candidate for commercially viable radiation detectors. They have attracted attention due to their high performance and low temperature solution processability, enabling low cost fabrication. An underexplored consequence of this fabrication route is the ability to crystallise around pre-placed structures. This enables the possibility of detectors with an embedded electrode architecture.
Silicon radiation detectors with embedded electrodes manufactured by etching are an established technology and have been deployed for high energy radiation physics applications in CERN. However, this architecture is not achievable for high-performance compound semiconductors such as CdTe and CZT as etching would destroy their fragile crystal structure and in-situ electrode encapsulation is not compatible with their CVD growth process.
A criticism of perovskite detectors is their modest carrier mobility compared to CZT or silicon, which demands prohibitively high electric fields to achieve the collection times required for ASIC integration and meaningful data rates for medical imaging. Detectors with embedded electrodes to collect charge carriers laterally, thus reducing the charge carrier transit time and trap probability compared to the planar configuration, holds promise to directly address this limitation.
This research presents the growth of FAPbBr₃ single crystals around a 2x2 array of gold wire electrodes, showing the first demonstration of this device architecture in a FAPbBr₃ single crystal radiation detector. Initial characterisation demonstrated a linear I-V response and sensitivity to X-rays. Future work will scale to a larger array with an increased area targeting gamma-ray spectroscopic performance with fast signal pulse rise times.