F. Paumier

Yttrium oxide thin films, Y2O3, grown by ion beam sputtering on Si

Thin films of yttrium sesquioxide, Y2O3, have been deposited on Si by ion beam sputtering at room temperature and 700 °C under an oxygen pressure of 4×10-3 Pa or by oxygen ion beam assisted deposition. The stoichiometry of these films was analysed by Rutherford backscattering spectrometry. The thickness and refractive index of the oxide were studied as functions of the wavelength by ellipsometry. The crystalline orientations of the deposited films were determined by x-ray diffraction. The micro- and nano-structure were investigated by transmission electron microscopy on cross section samples.

Yttrium sesquioxide, Y2O3, thin films deposited on Si by ion beam sputtering: microstructure and dielectric properties

Abstract Y2O3 thin films were in-situ deposited by ion beam sputtering on Si substrate. The influence of the deposition parameters are studied by X-ray diffraction, electrical measurements and high resolution transmission electron microscopy observations. The stress sate of the oxide layers is investigated by the sin2ψ method as a function of the deposition parameters and the post-annealing treatments. Oxygen ion beam assisted deposition process or post-annealing of as-deposited thin films lead to the same relaxation of the internal compressive stress within the oxide layer. An SiO2 layer sandwiched between Si and Y2O3 is always observed and should play a role both in the growing process and electrical properties of the MOS structure based on Y2O3 oxide layer. The results are interpreted in terms of diffusional process in the oxide, which are directly related to the temperature and the oxygen partial pressure during the growth process.

Interfacial reactions in Y2O3 thin films deposited on Si(100)

Abstract Interfacial reactions in thin films of Y 2 O 3 on Si(100) have been studied by means of energy dispersive X-ray analysis and high resolution transmission electron microscopy observations. Thin films of yttrium oxide were deposited at 700 °C by ion beam sputtering and then annealed at 700 and 900 °C under vacuum and in air, respectively. After an annealing treatment of 2 h at 900 °C in air a solid-state amorphization is observed at the interface Y 2 O 3 /SiO x . After annealing at 700 °C under vacuum a surprising phenomenon of electron beam irradiation induced epitaxial reconstruction is observed at the Si substrate surface.

Microstructural and conductivity changes induced by annealing of ZnO:B thin films deposited by chemical vapour deposition

Zinc oxide (ZnO) thin films have attracted much attention in recent years due to progress in crystal growth for a large variety of technological applications including optoelectronics and transparent electrodes in solar cells. Boron (B)-doped ZnO thin films are deposited by low pressure chemical vapour deposition (LPCVD) on Si(100). These films exhibit a strong (002) texture with a pyramidal grain structure. The ZnO films were annealed after growth; the annealing temperature and the atmosphere appear to strongly impact the layer conductivity. This work will first present the modification of the physical properties (carrier concentration, mobility) extracted from the simulation of layer reflection in the infrared range. At low annealing temperatures the mobility increases slightly before decreasing drastically above a temperature close to 250 °C. The chemical and structural evolution (XPS, x-ray diffraction) of the films was also studied to identify the relationship between microstructural modifications and the variations observed in the film conductivity. An in situ XRD study during annealing has been performed under air and low pressure conditions. As observed for electrical properties, the microstructural modifications shift to higher temperatures for vacuum annealing.

Magnetic properties of exchange biased and of unbiased oxide/permalloy thin layers: a ferromagnetic resonance and Brillouin scattering study

Microstrip ferromagnetic resonance and Brillouin scattering are used to provide a comparative determination of the magnetic parameters of thin permalloy layers interfaced with a non-magnetic (Al(2)O(3)) or with an antiferromagnetic oxide (NiO). It results from our microstructural study that no preferential texture is favoured in the observed polycrystalline sublayers. It is shown that the perpendicular anisotropy can be monitored using an interfacial surface energy term which is practically independent of the nature of the interface. In the interval of thicknesses investigated (5-25 nm) the saturation magnetization does not significantly differ from the reported one in bulk permalloy. In-plane uniaxial anisotropy and exchange bias anisotropy are also derived from the study of the dynamic magnetic excitations and compared with our independent evaluations using conventional magnetometry.