Microstructure study of a nanocrystalline two-phase ZrN_xO_y thin film

摘要

A nanocrystalline ZrN_xO_y thin film was deposited using hollow cathode discharge ion-plating (HCD-IP). ZrO_2 and ZrN phases were detected by X-ray diffraction in the as-deposited film, suggesting phase separation during the growth process. This research performed a transmission electron microscopy (TEM) study on the mechanism of phase-separation and distribution in ZrN_xO_y thin films and related the phase fraction with the film properties. Since the crystallographic orientations of the ZrO_2 and ZrN phases are random, the microstructure of the separated phases is studied with multiple central dark-field (MCDF) technique. The compositional distribution between the separated phases is analyzed with nano-beam energy dispersive X-ray spectroscopy (EDX). The results showed that zirconium oxynitride (ZrN_xO_y) thin film has a columnar structure with an alternate arrangement of columns of ZrN and ZrO_2, indicating that oxygen atoms are inter-columnarly segregated with a lateral diffusion distance lower than 20 nm.