Effect of substrate bias voltage on amorphous Si–C–N films produced by PVD techniques

SixCyNz thin films were deposited by reactive magnetron sputtering in glass and steel substrates. The films were grown in a rotation mode over a carbon and a silicon targets in a mixed Ar/N2 atmosphere. The substrates were held at a substrate temperature of 573 K. The argon flow was kept constant (100 sccm) and the nitrogen flow was 20 sccm or 25 sccm, in each one of the two series of produced films, resulting in a working pressure around 0.5 Pa. The substrate bias varied between grounded and -100 V. The films were analysed with respect to microstructure, state of chemical bonding and optical properties by X-Ray Diffraction (XRD), Raman Spectroscopy (RS), optical reflectance and transmittance. Raman spectroscopy was used as a probe of microstructural modifications induced by deposition conditions. The main features observed in RS spectra are the well-known D- and G-bands characteristic of amorphous carbon materials. The position, widths and intensity ratio of these bands are found to be dependent of the films deposition conditions. The refractive index, absorption coefficient, optical band gap and also the thickness were calculated from transmittance spectra obtained between 200 nm and 2500 nm.The residual stress of the coatings depends on deposition conditions and was calculated by measuring the substrate curvature before and after film deposition. The curvature of the samples was measured by laser triangulation in two series of two orthogonal directions. All coatings were in a state of compressive residual stress. The average hardness and Young’s modulus of the produced coatings is about 16 GPa and 170 GPa, respectively. The nano-hardness of the grounded produced samples presented values about 30% lower

Crystal size and crystalline volume fraction effects on the Erbium emission of nc-Si:Er grown by r.f. sputtering

Erbium-doped low-dimensional Si films with different microstructures were grown by reactive magnetron sputtering on glass substrates by varying the deposition parameters. Their structure and chemical composition were studied by micro-Raman and Rutherford backscattering spectrometry, respectively. In this contribution the Erbium emission is studied as a function of nanocrystalline fraction and average crystal sizes and also as a function of the matrix chemical composition. We discuss the temperature dependence of the Er3+ emission as well as the possible explanations of the low Er active fraction.FCT (POCTI/CTM/39395) and INTAS Project #03-51-6486

Photoluminescence of nc-Si:Er thin films obtained by physical and chemical vapour deposition techniques: The effects os microstructure and chemical composition

Erbium doped nanocrystalline silicon (nc-Si:Er) thin films were produced by reactive magnetron rf sputtering and by Er ion implantation into chemical vapor deposited Si films. The structure and chemical composition of films obtained by the two approaches were studied by micro-Raman scattering, spectroscopic ellipsometry and Rutherford backscattering techniques. Variation of deposition parameters was used to deposit films with different crystalline fraction and crystallite size. Photoluminescence measurements revealed a correlation between film microstructure and the Er3+ photoluminescence efficiency.FCT Project POCTI/CTM/39395/2001INTAS Project #03-51-648