Study on the band alignment of GaN/CH3NH3PbBr3 heterojunction by x-ray photoelectron spectroscopy

A GaN/CH3NH3PbBr3 heterojunction was fabricated by depositing a GaN thin layer on a CH3NH3PbBr3 single crystal by plasma enhanced atomic layer deposition. The band alignment of the GaN/CH3NH3PbBr3 heterojunction was studied by x-ray photoelectron spectroscopy. The valance band offset (VBO) is directly determined to be 0.13 ± 0.08 eV. The conduction band offset is deduced from the VBO and the band gaps, which turned out to be 1.39 ± 0.12 eV. Thus, the band alignment of the GaN/CH3NH3PbBr3 heterojunction is determined to be type-I. These results show that GaN is a promising material for carrier confinement in halide perovskite based light emitting devices.