Perovskite Grown in Gallium Nitride Nanowire Matrix for Stable and High‐Efficiency X‐Ray Detection

Abstract High‐quality quasi‐2D perovskites in a GaN nano‐wire matrix are grown to build a 3D hetero‐structure for high‐performance X‐ray sensing. In the 3D hetero‐structure, GaN nano‐wire matrix serves as an n‐type charge collector that can rapidly extract carriers through the bulk film of the perovskite layer. Together with a p‐type top electrode, a p–i–n diode with the 3D hetero‐structure is built, that exhibits a rectified current–voltage characteristic. After analyzing the interface energy alignment, it is found that the fermi levels of the perovskite and GaN are aligned in the dark, and a quasi‐fermi level splits upon illumination, introducing a built‐in electrical field at the interface. As a result, strong photo‐induced current is observed from the diode without an external field. Finally, the 3D diode for X‐ray detection demonstration is used, revealing a sensitivity of 308.9 µC Gy air −1 cm −2 at an exceptionally low applied field of 0.125 V µm −1 . The X‐ray‐induced signal from the 3D diode is stable after 155 cycles of X‐ray irradiation under a constant electric field. This demonstration informs a new 3D architecture for high‐performance X‐ray sensing, and it shows that GaN is a robust n‐type interface for perovskite optoelectronic devices.