Preparation of zinc oxide thin films by reactive pulsed arc molecular beam deposition

The structures and properties of ZnO thin films deposited on Si (111), Corning 2947 glass and polyimide substrates by pulsed arc molecular beam deposition (PAMBD) have been studied. PAMBD is an ablation technique that utilizes a high-voltage pulsed electrical arc discharge to provide a plasma source for oxide generation and subsequent material deposition. Metal oxide generation is accomplished by pulsing oxygen gas and using the arc discharge to create a high-temperature plasma. The resulting metal oxide product is expanded and deposited onto a room-temperature substrate situated within a vacuum chamber. In this work, ZnO thin films were grown by the PAMBD method and then characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and ellipsometry measurements to determine the film composition, structure, growth rate, and optical properties. SEM studies of ZnO films on different substrates all demonstrated that the PAMBD ZnO films were dense and have columnar structures. XPS revealed a highly stoichiometrical Zn and O (1:1) film composition representing chemically pure films. By observing ZnO thin films deposited on various substrates, we readily see the advantages of low-temperature thin film deposition due to the rapid cooling of the metal oxide product by the molecular beam supersonic expansion. This indicates that the PAMBD process is especially suitable for deposition of these materials upon temperature-sensitive substrates.