Structural, Morphological and Mechanical Characterisation of Molybdenum Nitride Thin Films Deposited by a Plasma Focus Device

Abstract

This research focuses on the characterisation of nanostructured molybdenum nitride (MoN) thin films deposited on glass substrates at room temperature using a low-energy (1.1 kJ) plasma focus device. The nanostructure, surface morphology, electrical resistivity and mechanical properties of MoN thin films were studied in terms of the number of shots required to prepare them. X-ray diffraction (XRD) analysis indicated that all of the deposited layers were polycrystalline in nature, possessing the γ-Mo2N (fcc) structure. The XRD results also revealed that the degree of crystallinity and residual stress of the thin films were strongly dependent on the number of shots. X-ray photoelectron spectroscopy showed the Mo 3d3/2, Mo 3d5/2, Mo 3p3/2 and N 1s peaks for all of the thin films, confirming the formation of the γ-Mo2N structure. Scanning electron microscopy images showed the growth of granular structures and then the formation of larger-sized agglomerates on the surfaces of the samples with increasing numbers of shots. Atomic force microscopy indicated that grain sizes on surface layers as well as the average and root mean square roughness increased for samples deposited with more shots. Furthermore, the variations in hardness and electrical resistivity of the deposited MoN thin films were qualitatively explained on the basis of the morphological properties of the samples.