STRUCTURAL-PROPERTIES OF NONSTOICHIOMETRIC ZINC-OXIDE FILMS

Authors report a study of the crystal structure and microstructure of sputtered non-stoichiometric ZnO//x thin films for which 0. 7 less than x less than 1. A substrate rf discharge was used to control film stoichiometry during deposition. All films had a columnar microstructures, and the film surface progressed from rough to smooth with increased oxidation. X-ray diffraction analysis detected no presence of crystalline zinc in any film. The crystallite size, strain and orientation of ZnO, detected in all films, was dependent on film composition and substrate rf discharge power. A model of film structure incorporating the competing effects of ion bombardment (causing amorphization) and increased oxygen content (creating improved crystallinity and orientation) is used to explain the observed variation of ZnO//x crystal structure.