The possibilities of SILD (successive ionic layer deposition) technology for modification of surface properties of nano-scaled SnO2 films for gas sensor applications were studied and are discussed in this article. Samples of SnO2 with thickness ranging from 30–40 nm were deposited by spray pyrolysis from SnCl4-water solutions. Nano-clusters of Pd and Ag, deposited by the SILD method were applied for surface modification. PdCl2 and AgNO3 were used as precursors for Pd and Ag deposition on the SnO2 surface.

It was found that the method of surface modification by SILD can be used for improving both the sensitivity and the rate of gas response of SnO2-based gas sensors to CO and H2. At the same time, the presence of Pd and Ag clusters on the surface of SnO2 depresses the gas response to ozone.

High-temperature catalysts containing Pd supported on high-surface area ceria-zirconia are optimum materials for fuel economy when automotive engines operate under high speed or load conditions. A prerequisite for developing such thermally stable catalysts is to gain a good understanding of the thermal deactivation modes contributing to the aging and degradation of catalysts in harsh thermal environments. It was discovered by X-ray diffraction that upon hightemperature aging, Pd may sinter into large (about 10 nm diameter) particles and become encapsulated in the ceria-zirconia. To confirm this conclusion, a prototype high-temperature catalyst containing Pd supported on high-surface area ceria-zirconia, aged at temperature above 1100 °C is studied by transmission electron microscopy (TEM).

The ceria-zirconia supported Pd (0.25 wt%) catalyst was aged at 1105 °C and calcined at 700 °C for 2 h. For TEM sample preparations, first of all, a large-size aggregate with diameter about 1 mm was selected and sandwiched between by two pieces of silicon crystal.

In this work we show that annealing of silicon/silicon‐dioxide/silicon structures in forming gas (N2:H2; 95:5) above 500°C leads to spontaneous incorporation of mobile H+ ions in the buried SiO2 layer. We demonstrate that, unlike the alkali ions feared as killer contaminants in the early days, the space charge distribution of these mobile protons within the buried oxide layer can be very well controlled and easily rearranged with relatively high speed at room temperature. The hysteresis in the flat band voltage shift provides a unique vehicle to study proton kinetics in silicon dioxide thin films. It is further shown how this effect has great potential as the basis for a reliable nonvolatile FET memory device that is expected to be competitive with state‐of‐the‐art Si‐based memory technologies. The power of this novel device is its simplicity; it requires few processing steps, all of which are standard in Si integrated‐circuit fabrication.

A nicrofabricated silicon-based chemical gas sensor with a discontinuous film of Pt / TiOx, as the active sensing component has been characterized by atomic force microscopy, environmental scanning electron microscopy, and transmission electron microscopy. A study of the device's multilayer structure and of the thin sensing film is undertaken to understand and control the sensing properties of the metal / semiconducting materials. The purpose of this research is to advance the understanding of the conduction mechanism and provide a basis for optimizing the sensing properties and microstructure of the sensing device.

Hydrogen bulk mobility plays an important role in determining a wide range of materials and electronic properties of hydrogenated amorphous silicon (a-Si:H). The existence of two types of hydrogen traps plays an important role in controlling hydrogen mobility in, and evolution of hydrogen from a-Si:H, however, theoretical and experimental literature values for the trap energetics vary considerably. We have developed a mean-field reaction-diffusion model which explicitly includes two trap states and realistic surface processes to model hydrogen evolution from a-Si:H. Modern numerical techniques were required to solve this challenging problem over the wide range of temperatures and concentrations encountered in typical hydrogen evolution experiments. The model is based on a number of experimentally established parameters. Comparison of our rigorous model with temperature programmed hydrogen evolution experiments provides a powerful method for characterizing the energetics, trap concentrations and diffusivity of hydrogen in a-Si:H.

Discrete, organometallic clusters containing S, Mo, and Fe or Co have been deposited intact on metal oxide supports. These supported clusters are subjected to temperature programmed decomposition (TPDE) which causes loss of the organic ligands and produces catalysts active for CO hydrogenation and thiophene hydrodesulfurization (HDS). In-situ Mossbauer spectra reveal that the surface is remarkably uniform and that high spin ferrous iron is the predominate species (ca. 90%) under catalytic reaction conditions. EXAFS and XANES spectra show that the clusters are irreversibly oxidized by the surface at ca. 400 K under H2.

A promising method for the preparation of sizeable quantities of structurally well-defined, highpurity MgO powder is reported. The morphology and surface uniformity of the powder is comparable to that of MgO smokes but with narrow size distribution of particles. Sample characterization of these oxide powders is accomplished by combining structural TEM/STEM examination with krypton gas adsorption isotherms. The latter technique is sensitive to the presence of surface hydroxyl groups and of surface roughness on an atomic scale. Highresolution TEM indicates a perfect cubic morphology, intra-crystallite orientation, and dendritic sintering of cubes. In the STEM mode sharp convergent beam electron diffraction patterns are obtained, and in thick specimen regions Kikuchi lines appear, indicating the absence of crystal defects. After prolonged outgassing to remove surface hydroxyl groups, a krypton adsorption isotherm contains a near vertical submonolayer riser and second layer step along with partial wetting features near saturation. These near-ideal dendritic ceramic powders, therefore, provide a research bridge between single crystal surface studies and large-scale powder technology.