Performance improvement of TiO2 nanorods ultraviolet photodetector by AlN thin film passivation

Surface defects on TiO2 nanorods (NRs) adsorb oxygen molecules and capture free electrons, thereby resulting in carrier recombination and reducing the photoelectric conversion performance of TiO2 NRs ultraviolet (UV) solidliquid heterojunction photodetectors. To solve this problem, wide energy bandgap AlN thin film was fabricated on TiO2 NRs to passivate the surface defects. Because of the chemical passivation effect of the AlN thin film and the quantum confinement effect of its wide bandgap, the number of defects and leakage loss were effectively reduced. According to the analysis results, the defect valence ratio of Ti2+ and Ti3+ in TiO2 NRs passivated by the AlN thin film decreased by 11.6%, the photoresponsivity of the device increased by 31.6%, the full-width at halfmaximum photoresponse decreased by 47.1%, and the response wavelength shifted from 360 to 350 nm. Overall, the wide energy bandgap AlN passivation layer exhibited the advantages of both chemical passivation and quantum confinement, making it highly suitable for improving the performance of UV photodetectors.