Solution-processed epitaxial growth of PIN photodiodes made of MAPbBr3 single crystals for high energy resolution gamma-ray spectroscopy

Abstract

Lead halide perovskite single crystals (LHPSCs), due to their high atomic number, excellent carrier transport properties, and tunable bandgaps, demonstrate unique potential in gamma spectroscopy detection. Among various LHPSCs, MAPbBr₃ (MA = CH₃NH₃) is the easiest to grow from solution with centimeter-scale size. Existing devices suffer from high noise under high bias or low charge collection efficiency under low bias. Our work aims to address this trade-off, designing a gamma spectroscopy detector that achieves high charge collection efficiency and low noise under high bias. This study proposes a structure of p-MAPbBr₃/i-MAPbBr₃/n-MAPbBr₃ PIN photodiode via heterovalent metal cooperation and epitaxial growth. By constructing such a homojunction PIN structure, defects near the interface were significantly suppressed. Under zero bias, the widths of the depletion layers for N–I and I–P reach 1.04 μm and 0.94 μm, respectively, demonstrating the effective growth of a PIN junction. Consequently, the noise is only 4.2 × 10³ electrons at 2400 V cm⁻¹ and the mobility–lifetime product is 3.44 × 10⁻³ cm² V⁻¹, thus significantly improving the carrier collection efficiency of over 80%. Experimental results reveal outstanding performance in detecting 662 keV gamma-ray photons, achieving an exceptional energy resolution of 3.5% under an electrical field of 2400 V cm⁻¹. This work provides useful information for the fabrication of perovskite-based gamma-ray detectors.