Ultraviolet photo-response properties of bush-like ZnO nanorods deposited by chemical bath deposition

Abstract

“Bush-like zinc oxide nanorods (ZnO NRs) has been deposited on soda-lime glass substrate via two step deposition process: seed layer deposition through Atmospheric chemical vapor deposition (APCVD) followed by chemical bath deposition (CBD) for growing NRs. Depositional parameters were carefully optimized so as to obtain a porous bush-like aggregation of ZnO NRs. X-ray Diffraction confirmed the formation of ZnO and scanning electron microscope showed bush-like aggregation of ZnO NRs. Transmission Electron Microscopy revealed that mostly non-polar {101¯0} and {112¯0} surfaces were exposed to the ambience. Room temperature Photoluminescence spectroscopy indicated the presence of mostly oxygen vacancy (VO) related defect states centered at 2.32 and 2.0 eV. Ultraviolet (UV) photo-response of the specimen was measured in air and nitrogen ambience. Higher photosensitivity (3166 % in nitrogen; 2233 % in air) but slower photo-response were observed under nitrogen ambience. It was found that UV photo-response properties of ZnO NRs were mostly a surface phenomenon dominated by adsorption-desorption mechanism of ambient oxygen molecules on the ZnO surface, mediated by surface defects related to VO, such as singly ionized state of VO. Bush-like aggregation of the ZnO NRs might have aided adsorption-desorption mechanism.”