Morphology and Composition of Lead-Cadmium Sulfide Photo-Sensitive Films

CdxPb1-xS films with a thickness of 620 and 680 nm were prepared by chemical precipitation from a reaction mixture containing lead salt, thiourea, alkali and cadmium acetate. The concentration of cadmium acetate was 0.01 and 0.1 mol/l. Electron-microscopic studies showed a fundamental difference in the morphology of the CdxPb1-xS thin films with a 10-fold difference in the concentration of cadmium acetate in the reaction bath. The results of energy dispersive analysis indicate the nonstoichiometry of the synthesized films on sulfur. Auger spectrometry revealed a high content of oxygen in the surface layer of the thin film coating CdxPb1-xS (up to 10 and 40 at. %). In the sample obtained from the reaction bath containing 0.01 mol / l of cadmium acetate, after ion etching at a depth of more than 30 nm, no oxygen was detected. In a sample prepared with a cadmium acetate content of up to 0.1 mol/l, the oxygen content does not exceed 3 at. %

Theoretical and Experimental Analysis of the Low Dielectric Constant of Fluorinated Silica

Fluorinated silica has a dielectric constant lower than that of F-free SiO2 and is a potential interlayer dielectric. We investigate the F-doped SiO2 with ab-initio modeling and various characterization techniques searching to explain the dielectric constant reduction. FTIR transmission and spectroscopic ellipsometry give us information about the ionic and electronic contributions to ε. Nuclear reaction analysis and Auger spectrometry measure F composition. XPS and FTIR provide information on the atomic structure of the film. We use several cells of cristobalite to model fluorinated silica using the electronic structure theory. The ground state geometry, vibrational density of states, electronic band structure, and Born effective charges are analyzed. The calculations suggest that it is the ionic component of the dielectric constant that is mostly effected by the F incorporation.

Theoretical and Experimental Analysis of the Low Dielectric Constant of Fluorinated Silica

ABSTRACTFluorinated silica has a dielectric constant E in the range of 3—3.5, lower than that of F-free SiO2 (ω=4). The reasons behind this reduction are controversial. It is not known whether the electronic or ionic contributions to the overall screening are being diminished upon F doping. To shed more light on this phenomenon we have studied F-doped SiO2 with ab-initio modeling and various characterization techniques. FTIR transmission and spectroscopic ellipsometry give us information about the ionic and electronic contributions to ω Nuclear reaction analysis and Auger spectrometry measure F composition. XPS and FTIR provide information on the atomic structure and stability of the film. We use a large cell of cristobalite to model fluorinated silica theoretically. The ground state geometry is obtained via energy minimization. We calculate the vibrational density of states and find a localized mode (Si-F stretch), in good agreement with FTIR transmission. We analyze the effects of F incorporation on the dielectric properties.

Growth of MgO by Metal-Organic Molecular Beam Epitaxy

MgO thin films were deposited on (100) Si substrates by metal-organic molecular beam epitaxy (MOMBE). Magnesium acetylacetonate was used as the precursor and an oxygen RF plasma was used as the oxidant. The films were characterized by a combination of transmission electron microscopy, Auger spectrometry and atomic force microscopy. Analyses indicate that the films directly deposited on Si substrates are stoichiometric, phase-pure, polycrystalline MgO with a [100] texture. Carbon contamination of the films resulting from precursor decomposition was not observed within detection limits. Furthermore, the growth rate of MgO has been systematically investigated as a function of growth temperature.

Solid solutions of AlN and SiC grown by plasma-assisted, gas-source molecular beam epitaxy

Solid solutions of aluminum nitride (AlN) and silicon carbide (SiC), the only intermediate phases in their respective binary systems, have been grown at 1050 °C on α(6H)-SiC(0001) substrates cut 3–4° off-axis toward [11$\overline 1$0] using plasma-assisted, gas-source molecular beam epitaxy. A film having the approximate composition of (AlN)0.3(SiC)0.7, as determined by Auger spectrometry, was selected for additional study and is the focus of this note. High resolution transmission electron microscopy (HRTEM) revealed that the film was monocrystalline with the wurtzite (2H) crystal structure.