摘要： Bi2O2Se thin film could be one of the promising material candidates for next-generation electronic and optoelectronic applications with the outstanding electrical and optoelectrical properties. However, the device performance based on the Bi2O2Se thin films was not fully explored in the photodetecting area. Considering that the electrical properties such as carrier mobility, work function and energy band structure of Bi2O2Se are thickness dependent, in-plane Bi2O2Se homojunctions consisting of layers with different thickness were successfully synthesized by CVD method across the terraces on the mica substrates, where terraces were created during the mica surface layer peeling off process. In this way, effective internal electrical fields were built up along the Bi2O2Se homojunctions, The Bi2O2Se in-plane homojunctions exhibiting diode-like rectification behavior with an on/off ratio of 102, what’s more, the photodetectors based on which were featured as highly sensitive and ultrafast with the maximum photoresponsivity of 2.5A/W and the lifetime of 4.8μs. Compared with the Bi2O2Se uniform thin films, the photo-electric conversion efficiency was greatly improved for the in-plane homojunctions.