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a b s t r a c tTo understand the influence of the oxygen on the crystallography of AlN thin films made by physical vapour deposition r.f. magnetron, three different oxygen content AlN films were prepared at room temperature for two values of the energy of the species building the film (low energy obtained by using: low power W, high pressure P; high energy obtained by using: high W, low P). It is observed that the crystalline morphology of the films not only depends on the process parameters (W and P), but is also particularly related to the oxygen content in the films. Regardless of P and W used here, low oxygen content films (5 at%) are columnar. The increase in oxygen content (15-30 at%) reduces the grain size without creating phases like Al 2 O 3 or AlNO, and very rich oxygen films (50 at%) are amorphous. From this study, assumptions are made for the localization of oxygen atoms in the AlN phase.

To synthesise homogeneous nanostructured aluminium nitride deposits on [0 0 1] Si substrates, the radio frequency magnetron reactive sputtering deposition process was tested. The microstructure and chemical composition of the films were studied as a function of the plasma working pressure P and the radio frequency power W. This paper describes the different morphologies that could be produced. Four microstructural types were identified and are presented versus the two parameters P and W as a map of microstructures. The first one is the well-known columnar microstructure. The second one is made of short rods. The third one consists of equiaxed particles while the fourth and last microstructure is amorphous. The ''deposit morphology-process parameters'' correlation is discussed. The progressive evolution of the microstructures could be related to the deposition rate of the films. Morphology was studied by transmission electron microscopy, and chemical investigations were performed by energy dispersive X-ray spectroscopy and Auger electron spectroscopy. r

This paper presents a thorough experimental investigation of erbium-doped aluminium nitride thin films prepared by R.F. magnetron sputtering, coupling Scanning Transmission Electron Microscopy X-ray-mapping imagery, conventional Transmission Electron Microscopy and X-ray diffraction. The study is an attempt of precise localisation of the rare earth atoms inside the films and in the hexagonal wü rtzite unit cell. The study shows that AlN:Er x is a solid solution even when x reaches 6 at.%, and does not lead to the precipitation of erbium rich phases. The X-ray diffraction measurements completed by simulation show that the main location of erbium in the AlN wü rtzite is the metal substitution site on the whole range. They also show that octahedral and tetrahedral sites of the wü rtzite do welcome Er ions over the [1.6-6%] range. The XRD deductions allow some interpretations on the theoretical mechanisms of the photoluminescence mechanisms and more specifically on their concentration quenching.