Polyoxometalates (POMs) are attractive candidates for the rational design of multi-level charge-storage materials because they display reversible multi-step reduction processes in a narrow range of potentials. The functionalization of POMs allows for their integration in hybrid complementary metal oxide semiconductor (CMOS)/molecular devices, provided that fine control of their immobilisation on various substrates can be achieved. Owing to the wide applicability of the diazonium route to surface modification, a functionalized Keggin-type POM [PW11 O39 {Ge(p-C6 H4 -CC-C6 H4 -${{\rm N}{{+\hfill \atop 2\hfill}}}$)}](3-) bearing a pending diazonium group was prepared and subsequently covalently anchored onto a glassy carbon electrode. Electron transfer with the immobilised POM was thoroughly investigated and compared to that of the free POM in solution.

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O tracer is used to investigate the development of porous anodic films at constant current in phosphoric acid on electropolished aluminum. A barrier layer and porous region form initially with the pore size related to the surface texture of the substrate. Subsequently, major pores emerge, with their sizes related to the anodizing voltage. The evolution of the film is accompanied by increases in growth rate and formation efficiency. The 18 O ions of a preformed oxide are retained in the film during anodization in a nonenriched electrolyte, with 18 O being partitioned among ͑i͒ the surface region of texture-dependent porosity, ͑ii͒ the walls of major pores, and, in diminishing amounts, ͑iii͒ the inner region of the barrier layer.

SiC is unique amongst the wide bandgap semiconductors in that the natural thermal oxide is stoichiometric SiO2, as is the case for silicon. The possibility of producing devices such as MOSFET in which thermal SiO2 is used as the gate insulator has motivated substantial work aimed at understanding the morphology and electrical properties of the SiO2/SiC interface and the processes responsible for thermal oxide growth. The oxide growth kinetics are quite different, parallel and anti-parallel to the crystal polar direction. We review the experimental study of the nature of the thermal oxide grown in ultra-dry oxygen and of the extended interfacial region at the SiO2/SiC interface on the nominally Si-terminated and C-terminated polar surfaces of hexagonal polytypes of SiC, highlighting how the use of stable isotopic tracing has helped to clarify processes for which kinetics measurements alone do not prove to be sufficiently incisive.

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The diffusion of defects during the thermal growth of SiO2 film on Si(100) in dry O2 was investigated using sequential treatments in natural oxygen (16O2) and in heavy oxygen (18O2) in a Joule effect furnace. The O18 depth profiles were measured with a depth resolution better than 1 nm, using the nuclear reaction narrow resonance O18(p,α)15N (ER=151 keV, ΓR=100 eV). From these profiles, we confirmed that just below the surface an exchange between the oxygen atoms from the gas phase and those from the silica occurs, even for silica films thicker than 20 nm. This fact is not predicted by the Deal and Grove model. A diffusion of oxygen related defects takes place in the near surface region, with an apparent diffusion coefficient D*=4.33×10−19 cm2/s for an oxidation temperature of T=930 °C and for an oxygen pressure of P=100 mbar.

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We investigated the transport of hydrogenous species during thermal nitridation of silicon dioxide films in ammonia by means of isotopic tracing of hydrogen. The dependence of the amount of hydrogen incorporated in the oxynitride films on the nitriding temperature and time, ammonia pressure, and on the initial oxide thickness was determined using methods that allow discrimination between the incorporation of hydrogen in the oxynitride films during nitridation and the effect of hydrogen adsorption during exposure of the oxynitride films to air. The depth profiles of hydrogen and the numher of hydrogen atoms that are exchanged between the oxynitride films and the ammonia gas are also established. The results indicate that the nitridation is driven by a mechanism whereby ammonia diffuses toward the oxide/Si interface reacting with the silica network. The nitridation of the surface and of the interface creates diffusion barriers whose effect on the nitridation process, as well as on the incorporation of hydrogen in the oxynitride films, is discussed.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-03-14 to IP