Pulse laser deposition of epitaxial TiO2 thin films for high-performance ultraviolet photodetectors

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.