Yves Campidelli

Covering and filling of porous silicon pores with Ge and Si using chemical vapor deposition

Filling of the pore network of porous silicon layers with Ge and Si has been demonstrated using a chemical vapor deposition (CVD) technique. It is shown that at low growth rate the species are deposited throughout the whole layer which can be completely filled. At high growth rate, the deposition takes place mainly on the top surface leading to pore mouth bridging. Investigation of the experimental data through a model shows that pore filling is a powerful tool for the study of the mechanisms involved in CVD processes at low temperature.

Growth kinetics and physical characterisation of Si1−xGexO2 films obtained by plasma assisted oxidation

Abstract Oxides of Si1−xGex alloys have been grown using the method of plasma assisted, anodic oxidation at temperatures Si ue5f8 O ue5f8 Si , Si ue5f8 O ue5f8 Ge and Geue5f8Oue5f8Ge bonds do not follow those expected on the basis of simple statistics related to the relative concentrations of Si and Ge. Auger electron spectroscopy and secondary ion mass spectroscopy reveal that the anodic oxides are spatially inhomogeneous being composed of mixtures of SiO2, GeO2 and Si1−xGexO2, consistent with the results of infrared analysis.

Si 1−x Ge x Oxidation by Plasma Assisted Processing: Oxide Uniformity and Electrical Properties

Anodic oxides of SixGe1−x (0 ≤ x ≤ 1 ) alloys have been made by plasma assisted oxidation in a microwave frequency (2.45 GHz) reactor working in the constant current bias mode. Oxide films ∼15 – 40 nm (depending upon the Ge concentration) were obtained in 10 minutes without a temperature rise of the substrate of more than 100 °C. Detailed infrared absorption studies of the oxides enabled the Si-O-Si, Ge-O-Ge and Si-O-Ge vibrational modes to be identified, the strongest being at 1056, 858 and 1000 cm−1 respectively. These modes are associated with the O asymmetric stretch, their values are at lower wavenumbers than in bulk oxides due partly to ultraviolet radiation induced structural modification and partly to thin film optic effects. A statistical model for the different bonds present in SixGe1−xO2, when used to simulate the infrared spectrum does not predict the experimentally observed form, the Ge-O-Ge peak is in general too intense in the experimental spectrum. Auger electron spectroscopy profiling of the SixGe1−x oxides suggests that there is a build-up of Ge close to the surface/oxide interface so that when combined with the infrared data, we conclude that there is a GeO2 rich region at the surface/oxide interface. The oxide is, however, globally stoichiometric. Electrical measurements (C(V) and interface state density) were begun on metal-oxide-semiconductor (MOS) capacitors for Si1−xGex. oxides over the range of concentrations 0 ≤ x ≤ 1. Only Si1−xGex oxides with x≤0.15 appear to yield satisfactory MOS capacitor curves.