Fluence-dependent sputtering yield measurement, surface morphology, crater depth, and hardness of laser-irradiated Zr in N2 and Ne environments

Abstract

Fluence-dependent sputtering yield measurements, surface morphology, crater depth, and hardness of laser-irradiated Zr in N2 and Ne environments have been investigated by employing an Nd:YAG laser (532 nm, 6 ns, 10 Hz). The targets were exposed to laser pulses at various fluences ranging from 16 J cm−2 to 60.8 J cm−2 under the N2 and Ne environments at a pressure of 10 Torr. Various features of irradiated targets, such as sputtering yield measurement, surface morphology, crater depth, chemical composition, and microhardness, are analyzed by quartz crystal microbalance (QCM), scanning electron microscope (SEM), optical microscope, energy dispersive x-ray spectroscopy (EDX), and Vicker microhardness tester techniques, respectively. QCM measurements reveal that the sputtering yield increases with increasing the fluence in both N2 and Ne environments. However, the values of sputtering yield are slightly higher in the case of N2 as compared to Ne. SEM analysis reveals the formation of cones, cavities, periodic ridges, and droplets at the central ablated areas, whereas the periodic ridges, cones, droplets, clusters, and agglomerates are formed at the inner boundaries of laser ablated Zr in both N2 and Ne. Distinct grain growth is observed at the outer boundaries in both environments. The characteristic features which are only present on Zr-irradiated surfaces in the case of N2 are cavities and in the case of Ne are droplets, clusters, and agglomerates. It is revealed that the surface structural growth is strongly dependent upon the laser fluence and nature of the ambient environment. The crater depth of laser-irradiated Zr is measured by using depth profilometry of an optical microscope. The higher observed values of sputtering yield and crater depth of laser ablated Zr in the case of N2 as compared to Ne are well correlated with distinct surface structures. EDX spectroscopy analysis reveals the nitride formation in the case of laser irradiation of Zr in a N2 environment. The Vicker microhardness tester reveals that the microhardness increases with increasing fluence under both environments; however, it is higher in Ne as compared to a N2 environment. Microstructured/nanostructured Zr can be highly useful in various advanced technological applications, e.g., in electronic, mechanical, fluidic, and optical devices. ZrN can be used as a hard and protective coating on mechanical tools as well as decorative coatings and diffusion barrier in p+/n junctions. The Zr plasma can be used as a source of thin film deposition as well as ion/electron implantation.