Growth of p-type ZnOS films by pulsed laser deposition

ZnO1−xSx films were deposited on quartz substrates by pulsed laser deposition (PLD) of ZnO1−xSx targets. The ZnO1−xSx films with S-contents of 0.03-0.17 were grown from the ZnO1−xSx targets sulfured at temperatures of 200 and 500 °C. The resistivity of the ZnO1−xSx films is slightly increased with the S-content. An increase of the O2-partial pressure in an atmosphere reduces the S-content in the films and drastically enhances the resistivity of the films. However, the carrier type of the films is still n-type. In order to incorporate excess S atoms into films, evaporation of Sulfur was performed during the PLD process. As a temperature of the S-evaporation is raised, the resistivity of the films is significantly enhanced and hole-conductivity appears in the films grown by the S-evaporation at 80 and 90 °C. By X-ray photoelectron spectroscopic measurements, the presence of SOx species is confirmed for the p-type ZnO1−xSx film. Both interstitial SO3 or SO4 clusters and complexes of Zn-vacancy with H are considered to be appropriate acceptors responsible for the hole-conductivity at room temperature.