Abstract: The main results and conclusions are presented of a round robin study of silicon oxide on silicon reference samples for ellipsometry. The oxide films with nominal thicknesses of 10, 50 and 120 nm are grown by thermal oxidation. The oxide film thicknesses have been determined by single wavelength ellipsometry (SWE), by spectroscopic ellipsometry (SE) and by cross-sectional conventional and high-resolution transmission electron microscopy (TEM and HREM) in different laboratories. The main conclusions are that special precautions have to be taken in order to use TEM as a reliable thickness measurement technique; that single wavelength ellipsometry can be used with great accuracy and reproducibility for the 50 and 120 nm film thicknesses but that it shows some inherent problems for the 10 nm films; and that spectroscopic ellipsometry showed for all film thicknesses an accuracy and reproducibility which is clearly superior to that of SWE.

Abstract: An alternative pathway to assemble mesoporous molecular sieve silicas is developed using nonionic alkylamines and N,N-dimethylalkylamines (SO) as structure-directing agents in acidic conditions. The synthesized mesostructures possess wormhole-like frameworks with pore sizes and pore volumes in the range of 20-90 Angstrom and 0.5-1.3 cm(3)/g, respectively. The formation of the mesophase is controlled by a counterion-mediated mechanism of the type (S(0)H(+))(X(-)I(+)), where S(0)H(+) are protonated water molecules that are hydrogen bonded to the lone electron pairs on the amine surfactant headgroups (S(0)H(+)), X(-) is the counteranion originating from the acid, and I(+) are the positively charged (protonated) silicate species. We found that the stronger the ion X(-) is bonded to S(0)H(+), the more it catalyzes the silica condensation into (S(0)H(+))(X(-)I(+)). Br(-) is shown to be a strong binding anion and therefore a fast silica polymerization promoter compared to Cl(-) resulting in the formation of a higher quality mesophase for the Br(-) syntheses. We also showed that the polymerization rate of the silica, dictated by the counterion, controls the morphology of the mesostructures from nonuniform agglomerated blocks in the case of Br(-) syntheses to spherical particles for the Cl(-) syntheses. Next to many benefits such as low temperature, short synthesis time, and the use of inexpensive, nontoxic, and easily extractable amine templates, the developed materials have a remarkable higher thermal and hydrothermal stability compared to hexagonal mesoporous silica, which is also prepared with nonionic amines but formed through the S(0)I(0) mechanism.

Abstract: Infrared absorption spectra of polyhedral and platelet oxygen precipitates are analyzed using a modified Day-Thorpe approach (J. Phys.: Condens. Matter 11 (1999) 2551). The aspect ratio has been determined by TEM measurements. The reduced spectral function and the stoichiometry are extracted from the absorption spectra and the concentration of precipitated interstitial oxygen. One set of spectra reveal a Frohlich frequency around 1100 cm(-1) and another around 1110-1120 cm(-1). It is shown that the shift in the Frohlich frequency is not due to a different stoichiometry, but due to the detailed structure in the reduced spectral function. The oxygen precipitates consist of SiO. with gammaapproximate to1.1-1.2+/-0.1. (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract: A method has been developed to determine the interstitial and precipitated oxygen concentration in highly doped n- and p-type silicon. 10-30-mu m-thin silicon samples in a mechanical stress-free state and without alteration of the thermal history are prepared and measured with Fourier transform infrared spectroscopy at 5.5-6 K. The measured oxygen contents in the as-grown Si samples agree well with those obtained with gas fusion analysis. In the highly boron-doped samples, the interstitial oxygen can be determined down to 10(17) cm(-3). (C) 1999 American Institute of Physics. [S0034-6748(99)04909-6].

Abstract: Infrared absorption spectra of oxygen precipitates in boron-doped silicon with a boron concentration between 10(17) and 10(19) cm(-3) are analyzed, applying the spectral function representation of composite materials. The aspect ratio of the platelet precipitates is determined by transmission electron microscopy measurements. The analysis shows that in samples with moderate doping levels (<10(18) B cm(-3)) SiOγ precipitates are formed with the same composition as in the lightly doped case. In the heavily boron-doped (>10(18) cm(-3)) samples, however, the measured spectra of the precipitates are consistent with a mixture of SiO2 and B2O3, with a volume fraction of B2O3 as high as 0.41 in the most heavily doped case. (C) 2004 The Electrochemical Society.

Abstract: For column structures, such as fee-based alloys viewed along the cube direction, the concept of electron channelling through the atom columns is more and more used to interpret the corresponding HREM images. In the case of(partially) disordered columns, the projected potential approach which is used in the channelling description must be questioned since the arrangement of the atoms along the beam direction might affect the exit wave of the electrons. In this paper, we critically inspect this top-bottom effect using multi-slice calculations. A modified channelling theory is introduced which turns out to be very appropriate for the interpretation of these results. For substitutionally disordered column structures, it is also discussed how to link the chemical composition of the material to statistical data of the HREM image. This results in a convenient tool to discern images taken at different thicknesses and focus values.