Influence of pulsed laser deposition (PLD) parameters on the H_2 sensing properties of zinc oxide thin films

摘要

Thin films of n-type ZnO were produced by a novel two-target, two-pulsed laser deposition technique. This method allows on-line control of the film properties by just changing the laser parameters. A number of deposition parameters, as well as the dopants (Al, Au) and the substrate type (Si, SiO_2, glass), were changed. The sensing properties of the films were tested upon exposure to a H_2 flow in air ambient at working temperatures between 150 and 210℃. Undoped ZnO thin films, deposited on SiO_2 substrates at 200℃, in ambient O_2 at 20 Pa and with a laser fluence of 9.6 J/cm~3, exhibited a maximum sensitivity (ΔR/R_0) higher than 97% and a response time lower than 3 min at the working temperature 180℃. Decrease of the working temperature to 150℃ was achieved by means of surface sensitization of films after deposition of Au nanoclusters on the surface of the above-mentioned ZnO thin films.