Periodically structured ZnO thin films for optical gas sensor application

Thin zinc oxide (ZnO) films have been produced by pulsed laser deposition on periodically structured substrates. The films were grown at substrate temperature of 300 °C and 5 Pa oxygen pressure. The periodically structured substrates were prepared by applying a combination of a modified lithography technique with a typical holographic exposure. After the deposition of the ZnO, the film groove period is preserved whereas the depth decreases (h ∼ 100 nm) for a film thickness of about 445 nm. The periodical structure was used for easy coupling of the light into the films to ensure optical detection. Sensitivity of the ZnO sensors to 1000 ppm butane diluted in nitrogen was proven. The response time of about 1 min was evaluated.