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A cross-section TEM image of a cubic-boron nitride film reveals the well-known layered structure: amorphous-BN, textured turbostratic BN with c-axis parallel to substrate, textured nanocrystalline (111) c-BN planes and turbostratic BN upper layer. The thickness of the sp2 layer depends on deposition conditions and in the case of IBAD techniques lies between 10 and 30 nm. A lack of knowledge about this sp2 BN layer with c-axis parallel to the substrate is mainly due to its small thickness and to the fact that it is a buried layer. Nevertheless, we consider that it is possible to obtain films with the same features using deposition conditions as close as possible to those for h-BN to c-BN transition. Pure h-BN films with thickness up to 200 nm were deposited and analysed using stress, density and HRTEM measurements. These sp2 films have compressive stress up to 10 GPa, density up to 3.2 and a rhombohedral structure. [Copyright &y& Elsevier]

In this work we are interested in analyzing the texture of aluminum nitride thin films deposited by direct-current magnetron sputtering and high-power impulse magnetron sputtering on silicon (100) substrates. The texture characterization of aluminum nitride films was performed by X-ray diffraction. The pole figures have indicated that in both methods direct-current magnetron sputtering and high-power impulse magnetron sputtering, the microstructure is a (0001) strong fiber texture, with a tilted c-axis in the case of direct-current magnetron sputtering. Moreover, the texture analysis allowed the characterization of the cubic phase of aluminum nitride, which most likely constitutes a transition layer between the hexagonal aluminum nitride and the silicon substrate. The misfits' calculations between the different structure cells (silicon, hexagonal aluminum nitride and cubic aluminum nitride) confirm that the growth of the hexagonal aluminum nitride in the form of (0001) fiber is facilitated by this transition layer. [ABSTRACT FROM AUTHOR]

Abstract: Low-temperature Aluminum Nitride (AlN) thin films with a thickness of 3μm were deposited by Direct-Current magnetron sputtering on sapphire substrate. They present optical properties similar to those of epitaxially grown films. Different characterization methods such as X-Ray Diffraction, Transmission Electron Microscopy and Atomic Force Microscopy were used to determine the structural properties of the films such as its roughness and crystallinity. Newton interferometer was used for stress measurement of the films. Non-destructive prism-coupling technique was used to determine refractive index and thickness homogeneity by a mapping on the whole sample area. Results show that AlN films grown on AlGaN layer have a high crystallinity close to epitaxial films, associated to a low intrinsic stress for low thickness. These results highlight that it is possible to grow thick sample with microstructure and optical properties close to epitaxy, even on a large surface. [Copyright &y& Elsevier]

Abstract: Mo(Cr) thin films were deposited by an Ionized Physical Vapor Deposition process i.e. Ionized Magnetron Sputtering (IMS). This deposition technique enables to ionize the neutral metallic sputtered species by a secondary plasma generated through a radio-frequency (RF: 13.56 MHz) powered coil. Thus, by acting on the substrate bias voltage, on the argon pressure and on the RF power applied to the coil, the ion energy and flux onto the substrate can be controlled. Various types of microstructure are then obtained, leading to a wide range of residual stresses in films from compressive to tensile. The control of both the microstructure and the related stress using the IMS process offers new opportunities in elaborating stress-engineered micro-objects for micro-electromechanical systems (MEMS). Residual stresses in the whole volume of the film were measured ex situ by Stoney curvature method and X-ray diffraction was applied to get the in-grain contribution (i.e. the crystallites) to the total residual stresses using the sin2 ψ  method. Besides, the grain morphology and local structure of the film were characterized by transmission electron microscopy. Relationship between synthesis conditions, microstructure, film morphology and residual stresses in Mo(Cr) films deposited by IMS is presented in this study and leads to a multi-scale description of the mechanisms of stress formation. The stress values determined from both techniques may be explained thanks to the analyzed morphological and microstructural features in the films. [Copyright &y& Elsevier]