Effect of oblique sputtering on microstructural modification of ZnO thin films

The effects of oblique sputtering on microstructural modification of ZnO films were investigated. Surface morphologies of the films were profoundly modified with an incidence angle. By using pure Ar gas, etch pits, pyramids, ridge, and ledgelike structures were developed on the film surface. By using Ar/O-2 mixture gas, large elongated grains, which aligned perpendicular to the direction of incidence vapor at incidence angle above 80 degrees, were formed on the fine columnar matrix. The x-ray Schulz method showed that the (002) pole located away from the direction of incoming vapor at low incidence angles, while the (101) pole uniformly distributed as a concentric ring. For films deposited at high angles, the (002) pole inclined toward an incoming vapor, while the (101) pole moved to the central region. In this case, (110) poles had a tendency to align biaxially. The topological modification and crystallographic orientation change could be explained with an adatom mobility and crystallographic geometry contribution. (C) American Vacuum Society.