Ti6Al4V is widely used as a metallic biomaterial and in cutting-edge fields of biomedicine that must comply with emerging technological demands such as smart wearable pieces and implantable electronic devices. The current study renders a new insight in controlling the conductivity and the hardness of TaN thin film based on the deposition conditions and provide a correlation between the structural and other properties of TaN films, which is useful for a variety of semiconductor devices. The obtained results from the four-point probe illustrate that the specimen with higher nitrogen content displays the minimum sheet resistance due to a decrease in inter-grain boundaries emanated from the larger grain size. The results of mechanical properties show a decrease in the hardness upon increasing the nitrogen concentration due to variation in the grain size. Furthermore, quantitative characterization of 3-D surface morphology from AFM micrographs is obtained by multifractal and stereometric analyses. Atomic force microscopy (AFM) results show larger surface roughness for the tantalum nitride thin films with higher nitrogen concentration owing to grain boundary diffusivity. As nitrogen concentration increases from 10 to 25%, the average domain size increases. Field emission scanning electron microscopy images indicate that the tantalum nitride thin films are made of crystal domains with almost regular boundaries. X-ray diffraction results show characteristic peaks of FCC tantalum nitride with crystallite size gradually increasing upon an augmentation in the nitrogen concentration. The influence of nitrogen concentration on various features of tantalum nitride thin films is systematically studied. Tantalum nitride thin films are grown on silicon wafers using a mixture of Ar/N2 using DC magnetron sputtering. The results obtained through this evaluation showed a direct relationship between the power used and the improvement of the properties against corrosion for specific grain size values. In order to determine the corrosion resistance of the coatings, electrochemical impedance spectroscopy and polarization resistance were employed in the Tafel region. For all produced samples, the δ-TaN phase was observed despite the low N2 content used in the process (since for low N2 content it was expected to be possible to obtain films with α-Ta or hexagonal ε-TaN crystalline structure). Results obtained showed a strong correlation between the growth energy with the crystallinity of the samples and the formation of the possible phases since the increase in the growth power caused the samples to evolve from an amorphous structure to a cubic monocrystalline structure.
Atomic force microscopy analysis allowed us to obtain values for surface grain size and roughness which were related to growth mechanisms in accordance with XRD results. Phase, line profile, texture, and residual stress analysis were carried out from the X-ray diffraction patterns obtained. The effect of the target power on the formation of the resulting phases and the microstructural and morphological characteristics was studied using XRD and AFM techniques, respectively, in order to understand the growth mechanisms. All synthesis parameters such as gas ratio, pressure, gas flow, and substrate distance, among others, were fixed except the applied power of the source for different deposited coatings. In this work, thin films of TaN were synthesized on 304 steel substrates using the reactive DC sputtering technique from a tantalum target in a nitrogen/argon atmosphere. The dense δ-TaN structure with reduced columnar grains and micro-voids increases the strength of the TaNx film. The higher ICP power enhances the mobility of Ta and N ions, which stabilizes the δ-TaN phase like a high-temperature regime and removes the micro-voids between the columnar grains in the TaNx film. δ- TaN phase becomes the main phase in all nitrogen fractions investigated. By increasing ICP power from 100 W to 400 W, the f.c.c.
As nitrogen gas fraction increases from 0.05 to 0.15, the TaNx phase evolves from body-centered-cubic (b.c.c.) TaN0.1, to face-centered-cubic (f.c.c.) δ-TaN, to hexagonal-close-packing (h.c.p.) ε-TaN phase.
The detailed microstructural changes of the TaNx films were characterized utilizing transmission electron microscopy (TEM), as a function of nitrogen gas fraction and ICP power. Tantalum nitride (TaNx) thin films were grown utilizing an inductively coupled plasma (ICP) assisted direct current (DC) sputtering, and 20-100% improved microhardness values were obtained.
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