EFFECTS OF EXCESS ZINC ON THE STRUCTURE OF REACTIVELY SPUTTERED ZINC-OXIDE FILMS

Experimental results from DC reactive sputtering of a zinc target for growing zinc oxide films are reported. Special emphasis was placed on conditions to obtain films with excess zinc and its effects on film structures. Results suggested that competition between oxidation of the zinc target and its rate of being sputtered away plays a critical role in deciding the stoichiometry of grown films. This competition, in turn, results from the coupled effects of DC power and oxygen fraction in the chamber. A higher oxygen fraction is needed to produce transparent, stoichiometric and highly oriented films. Data showed that when a slight excess of zinc was included in the ZnO film, its color (i.e. transparency) and columnar structure changes accordingly.