Deposition and characterization of epitaxial Ta-doped TiO2 films for ultraviolet photoelectric detectors

Undoped and tantalum-doped titania (TiO₂:Ta) films were synthesized via metalorganic chemical vapor deposition (MOCVD). The crystallization qualities, surface morphologies and optical properties of the deposited films were systematically characterized. The results indicated that the films having low doping levels were epitaxial anatase titania along [001] orientation with high transparency in visible region. The optical band gap could be modulated from 3.38 to 3.52?eV by controlling Ta doping levels. Ultraviolet (UV) photoelectric detectors with metal-semiconductor-metal (MSM) structure were designed and fabricated based on the undoped and Ta-doped films. The maximum spectral response of 32.3?A/W was detected at about 315?nm for the 1% Ta-doped TiO₂ film-based detector. The detectors based on the undoped and 1% Ta-doped TiO₂ films also presented good temporal responses and visible-blind characteristics, showing excellent UV light detection performances.