Synthesis and Characterization of MAPbBr₃ Perovskites for Radiation Detection Applications

High resolution room temperature radiation detection is important, with applications in national security and nuclear nonproliferation. A typical high resolution solid state detector, Ge, has high μ and τ values for electrons and holes, but a small band gap 0.6 eV which requires operation at cryogenic temperatures. Another common solid state detector is CZT with a band gap of 1.6 eV, which eliminates cooling constaints. The μ and τ values are lower than Ge, leading to asymmetric charge induction and lower resolution. Methylamunium lead halide pervoskites, like MAPbBr₃, have emerged as an attractive candidate over CZT. MAPbBr₃ has a greater band gap than CZT and is expected to have great charge carrier transport properties, high resistivity, low density of defects, and low-cost synthesis/processing of large crystals from solution. However, moisture instability and the presence of lead are barriers for further development. In our study, we carry out material characterizations of MAPbBr₃ crystals grown at UNLV. Surface and compositional analysis of the samples are performed using Nomarski microscopy, SEM/EDS, TEM, and PL measurements. In EDS analysis, we confirm the samples are MAPbBr₃, and TEM shows single crystalline behavior. The presence of phase segregation in the samples is not present. PL of samples in the 300-1050nm spectrum show the following: the roughest sample, OH2B, shows a peak ~532nm. Sample OH3B has a smoother surface and shows a peak ~536nm. Lastly, sample OH6B, shows the lowest peak ~528nm.