Pulse laser deposition of epitaxial TiO 2 thin films for high-performance ultraviolet photodetectors

Abstract The authors report on high quality TiO2 epilayers grown on lattice-matched LaAlO3 substrates by pulsed laser deposition. A prototype of metal–semiconductor–metal ultraviolet (UV) photodetector based on TiO2 was fabricated by employing Au as the Schottky contact metal. The UV–visible transmittance spectrum of the TiO2 epilayer and the spectral response of the photodetector reveal that the deposited anatase TiO2 thin film exhibits excellent visible-blind UV characteristics with an optical bandgap of 3.25 eV. In addition, the fabricated photodetector exhibits a high UV-to-visible rejection ratio (R270 nm/R400 nm) of 105 while displaying a low dark current of 0.25 pA under 5 V bias and a high responsivity of 0.21 A/W, suggesting a potential application in UV photodetection.