Novel Transparent and Self-Powered UV Photodetector Based on Crossed ZnO Nanofiber Array Homojunction.

A novel self-powered UV photodetector based on electrospun ZnO nanofiber arrays is introduced. Aligned pure ZnO nanofibers and Ag-doped p-type ZnO nanofibers are processed perpendicular to each other, and p-n junction arrays of ZnO nanofibers are fabricated as a result. Owing to the intrinsic intervals between nanofibers, the device is fully transparent on quartz substrate. Various characterization methods including TEM, XRD, and XPS are used to testify the existence form of Ag element in ZnO nanofibers, and a field effect transistor is constructed to judge their conductivity. It is discovered that the Ag doping process not only transforms ZnO to p-type conductivity, making it possible to build this self-powered photodetector, but also forms Ag nanoparticles in ZnO nanofibers and thus helps reduce the response time. Benefiting from the abovementioned dual effects, this UV detector is found to have an enhanced performance, with the on-off ratio up to 104 at zero bias and a rather short rise/decay time of 3.90 s/4.71 s.