Abstract
This work reports on the properties of lead halide perovskite single crystals specifically for the application of solid state radiation detection. An appreciation of all the key stages in advancing radiation detectors have been developed, starting from the growth of the detector material, processing the as-grown crystals, device fabrication and finally device characterisation. This has resulted in a comprehensive PhD thesis, the novelty of which originates from the choice of perovskite material (FAPbBr3) and the breadth of properties investigated, as well as making direct experimental comparisons with other commonly reported perovskite materials (MAPbBr3 and CsPbBr3).
Single crystals were synthesised using a solution-growth method where it was discovered that the quality of produced crystals highly depended on the surrounding environment, in particular the temperature profile and the background light levels. The surface roughness of a detector material was determined to have a direct impact on the overall device performance and therefore various surface processes were developed to reduce roughness and improve surface quality.
The charge transport of devices determines their effectiveness as radiation detectors and therefore these properties were studied extensively. FAPbBr3 devices achieved high resistivity values of the order 10^9 Ωcm with electron mobilities of up to 30 cm^2/Vs and electron mobility-lifetime products of up to 1 x 10^-3 cm^2/V. Generally, the electron transport in FA devices was better than hole transport, MA devices were observed to have more balanced electron and hole transport, and Cs devices had significantly better hole transport. The X-ray sensitivity of devices was also assessed where Cs devices showed the highest sensitivity up to 4000 μC/Gycm^2, followed by FA (2000 μC/Gycm^2) then MA (1000 μC/Gycm^2) which is comparable to current commercially available detector sensitivities. The response to gamma rays were also studied and the reasons for challenges in acquiring well resolved gamma-energy spectra were investigated.