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CrN thin films with an N/Cr ratio of 95% were deposited by reactive magnetron sputtering onto (0001) sapphire substrates. X-ray diffraction and pole figure texture analysis show CrN (111) epitaxial growth in a twin domain fashion. By changing the nitrogen versus argon gas flow mixture and the deposition temperature, thin films with different surface morphologies ranging from grainy rough textures to flat and smooth films were prepared. These parameters can also affect the CrN(x )system, with the film compound changing between semiconducting CrN and metallic Cr2N through the regulation of the nitrogen content of the gas flow and the deposition temperature at a constant deposition pressure. Thermoelectric measurements (electrical resistivity and Seebeck coefficient), scanning electron microscopy, and transmission electron microscopy imaging confirm the changing electrical resistivity between 0.75 and 300 m omega cm, the changing Seebeck coefficient values between 140 and 230 mu VK-1, and the differences in surface morphology and microstructure as higher temperatures result in lower electrical resistivity while gas flow mixtures with higher nitrogen content result in single phase cubic CrN. Funding Agencies|European Research Council under the European Community/ERC [335383]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Swedish Foundation for Strategic Research (SSF) through the Future Research Leaders 5 program; Knut and Alice Wallenberg Foundation under the Wallenberg Academy Fellows program; Swedish Research Council (VR) [2016-03365]; European Union; Danish Innovation Fund for the NanoCaTe project [604647]; Danish Innovation Fund for the CTEC project [1305-00002B]

The relation between the nanostructure and the mechanical properties of Nb x -CoCrCuFeNi high entropy alloy thin films was explored. With increasing Nb concentration (0 to 24 at.% Nb), a transition from a single phase face-centered cubic solid solution to an amorphous phase is observed. At intermediary Nb fractions (5 to 15 at.% Nb) a nanocomposite structure is formed that consists of nanosized crystallites embedded in an amorphous matrix. The nanocomposite structure leads to an increase in hardness beyond the Hall-Petch breakdown. The shear and Young's moduli decrease with increasing Nb concentration, which is beneficial for the alloy ductility.

The growth mode during physical vapor deposition of metallic thin films is very sensitive to the presence of impurity species. These impurities can originate from the residual ambient gases present in the vacuum chamber and usually impede continued crystal growth by inducing renucleation. During magnetron sputtering at intermediary base pressures (~ 10− 4 Pa), the effect of these impurities can be estimated from the ratio of the impurity flux to the metallic flux. In this study, the influence of the ambient impurity flux on the growth mode of CoCrCuFeNi High-Entropy Alloy (HEA) thin films is investigated. It is shown that the impurity-to-metal flux ratio effectively controls the texture, grain size, porosity, and elastic properties of the nanocrystalline CoCrCuFeNi thin films. A less clear (111) fiber texture is observed at higher impurity-to-metal flux ratio. With increasing impurity-to-metal flux ratio the grain size decreases while the porosity increases. The elastic constants, and Young's modulus for CoCrCuFeNi is reported to be the highest for the 〈111〉 direction. Hence, the change in film texture also affects the elastic constants and Young's modulus which tend to become lower as more grains with different orientation are observed at higher flux ratios. This study demonstrates that an exact knowledge of the impurity-to-metal flux ratio, or otherwise stated, of the base pressure and deposition rate during sputter deposition is imperative for the synthesis of HEA films with reproducible properties.

We report time-resolved acoustic measurements in the picosecond range performed with a 100 nm lateral resolution. A near field optical microscope operating in reflection geometry and coupled with a standard picosecond acoustic setup is described. Results obtained on thin film are discussed and prove that the sensitivity of our system allows the observation of thermal features and acoustic signals such as echoes and surface waves. Patterned structures made of submicrometric metallic dots have also been studied: it is demonstrated that, owing to the high lateral resolution which we obtained, vibrational modes of a single dot are detected.

The characteristics of a few experimental near-field optical microscopes, located in different laboratories, have been compared on the basis of their ability to image a well-defined submicrometer test object.