Photoelectric properties of nano-ZnO fabricated in mesoporous silica film

Via electrochemical deposition, nanosized zinc oxide (nano-ZnO) is prepared within a template of mesoporous silica (MPS) film fabricated on a conductive substrate. Enhanced dark current from the nano-ZnO in MPS film is obtained because nano-ZnO is located in the nanosized pores of MPS. Most of the nano-ZnO surface is prevented from contacting ambient oxygen, and the combination of oxygen with free electrons of this n-type semiconductor is avoided; thus the free electrons increase the conductivity. Photodetection to ultraviolet (UV) light is examined at the exciting wavelength of 365 nm. The photocurrent with fast growing and decay times is observed due to the photo-generated holes being trapped at the interface between ZnO and pore walls of MPS film, while producing the photocurrent by photo-generated electrons. Photoluminescence (PL) spectrum of nano-ZnO in MPS film at room temperature shows increased amount of oxygen vacancies in these nano-ZnO, which might contribute to the conductivity.