γ-Ray PIN Diodes Made of CH3NH3PbBr3 Perovskite Single Crystals Assisted with Highly Doped Epitaxial Layers
Yunping Qiu, Yuzhu Pan, Qianqian Huang, Yulian Zhang, Jinbao Chen, Youwen Liu, Xin WangAbstract
MAPbBr3 (MA = CH3NH3) perovskite single-crystal γ-ray detectors based on Schottky diodes typically suffer from electrochemical reactions at the cathode under an applied bias. A low-resistance contact could decrease the electrical field near metal/MAPbBr3 single crystals. However, it is difficult to achieve highly conductive n-type/p-type layers made of MAPbBr3 single crystals. In this work, we report that n-type and p-type MAPbBr3 can be achieved by incorporating heterovalent dopants and adjusting the MABr:PbBr2 molar ratio. Through epitaxial growth, γ-ray PIN diodes consisting of n-type and p-type layers are fabricated, which establish sufficient energy barriers. The resulting γ-ray PIN diode (8.4 × 8.5 × 4.1 mm3) exhibits a dark current of only 238 nA under a bias of −1000 V. Owing to the absence of a strong electric field near the cathode, cathode stability is improved. The balanced charge transport property is further confirmed by time-of-flight and Hecht analyses. The γ-ray PIN diode achieves an energy resolution of 3.1% for 662 keV γ-ray photons.