Improvement of the photocatalytic degradation property of atomic layer deposited ZnO thin films: the interplay between film properties and functional performances

Abstract

In this work, we have evidenced the impact of stoichiometry on the photocatalytic properties of ZnO nanofilms grown by atomic layer deposition (ALD). We point out the importance of hydrogen incorporation and propose here a model explaining the presence of Zn–OH impurities in the form of a ZnO_xH_y amorphous matrix hosting ZnO crystallites. We evidence that this phase prevails in films grown at low temperatures and prevents the photoluminescence and photocatalytic activity of ZnO films. We also point out that high temperature ALD processes promote the preferential growth of ZnO films in the (002) orientation, leading to a significant increase of the film wettability and so their photocatalytic degradation performances.