Silicon based substrate with calcium aluminosilicate environmental/thermal barrier layer

A barrier layer for a silicon containing substrate which inhibits the formation of gaseous species of silicon when exposed to a high temperature aqueous environment comprises a calcium alumino silicate

Silicon based substrate with calcium aluminosilicate/thermal barrier layer

A barrier layer for a silicon containing substrate which inhibits the formation of gaseous species of silicon when exposed to a high temperature aqueous environment comprises a calcium alumino silicate

Low-Temperature Deposition of Zirconium and Hafnium Boride Films by Thermal Decomposition of the Metal Borohydrides (M[BH4]4)

Conductive (150 μω cm), adherent films of zirconium and hafnium borides have been deposited on various substrates by the low-temperature (100-270 °C) thermal decomposition of Zr[BH4]4 and Hf[BH4]4. Auger electron spectroscopy of these films shows that their composition is ZrB2 and HfB2. The film surfaces are oxidized and slightly carbon contaminated. However, the bulk contains less than 1 at. % C or O. This synthesis is by far the lowest temperature preparation of these materials (plasma-enhanced chemical vapor deposition of TiB2 requires 480-600 °C) and holds great promise for the use of these materials in electronics applications

Electronic Structure Characterization of Hydrogen Terminated n-type Silicon Passivated by Benzoquinone-Methanol Solutions

The electrical passivation mechanism of benzoquinone-methanol solutions on silicon has been examined through the study of the silicon surface electronic structure. Surface photovoltage (SPV) measurements using both X-ray photoelectron spectroscopy (XPS) and scanning Kelvin probe microscopy (SKPM) indicate a downward band bending of H-Si and benzoquinone (BQ) and methanol (ME) treated samples. This suggests the creation of an accumulation layer of majority carriers near the surface, with a significant field-effect contribution to the observed surface passivation. The highest SPV values recorded for the ME-Si and BQ-Si samples of about −220 mV are approaching the Fermi level—conduction band crossover. Density functional theory (DFT) calculations show that a dipole is formed upon bonding of BQ radicals on the surface, decreasing the surface electron affinity and work function. Considering the 0.07 eV shift due to the dipole and the 0.17 eV downward band bending, the work function of BQ-Si is found to be 4.08 eV. Both the dipole and downward band bending contribute to the formation of surface electron accumulation, and decrease the minority carrier density of n-Si passivated by BQ

Aluminum Substitution in Ba2YCu3O7

We have investigated the effect of aluminum incorporation on the structure and superconducting transition temperature of single crystals of high-Tc cuprate perovskite superconductors. The use of alumina crucibles for crystal growth results in incorporation of aluminum to varying extents in crystals of composition Ba2YCu3-xAlxO7, x=0-0.22. We have performed x-ray studies on several crystals to determine structural effects of Al incorporation. We find that aluminum substitutes only for copper atoms in the chains. Superconducting transition temperatures Tc determined by dc diamagnetic susceptibility measurements change only slightly, to 80 K for x=0.1, then drop sharply with higher aluminum concentrations. Results are discussed in relation to the importance of the Cu-O chains and oxygen stoichiometry to superconductivity in Ba2YCu3O7