Gallium nitride (GaN) is a compound semiconductor that has tremendous potential to facilitate economic growth in a semiconductor industry that is silicon-based and currently faced with diminishing returns of performance versus cost of investment. At a material level, its high electric field strength and electron mobility have already shown tremendous potential for high frequency communications and photonic applications. Advances in growth on commercially viable large area substrates are now at the point where power conversion applications of GaN are at the cusp of commercialisation. The future for building on the work described here in ways driven by specific challenges emerging from entirely new markets and applications is very exciting. This collection of GaN technology developments is therefore not itself a road map but a valuable collection of global state-of-the-art GaN research that will inform the next phase of the technology as market driven requirements evolve. First generation production devices are igniting large new markets and applications that can only be achieved using the advantages of higher speed, low specific resistivity and low saturation switching transistors. Major investments are being made by industrial companies in a wide variety of markets exploring the use of the technology in new circuit topologies, packaging solutions and system architectures that are required to achieve and optimise the system advantages offered by GaN transistors. It is this momentum that will drive priorities for the next stages of device research gathered here.

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The interaction of oxygen with titanium has been studied by X-ray photoelectron spectroscopy. Methods for analysing composite photoelectron spectra (curve fitting, deconvolution and spectral subtraction) are discussed and examined critically and the advantages of the 'difference spectra' approach highlighted. Evidence for variable oxidation states (suboxides) is obtained from an analysis of the Ti(2p) spectra observed during the formation of thin oxide films (ca. lOA). Angular-dependent studies established that the lower oxidation states Ti2+ and Ti3+ were formed preferentially at the metal-oxide interface, whereas Ti4+ species were dominant at the oxide-gas interface. The distribution of the oxidation states within the thin oxide overlayer may be altered by thermally induced diffusion of Tio species from the metal substrate; the latter can occur at low temperature (ca. 200 K) for the thin oxide film regime investigated.

Flash memory is the most widely used non-volatile memory device nowadays. In order to keep up with the demand for increased memory capacities, flash memory has been continuously scaled to smaller and smaller dimensions. The main benefits of down-scaling cell size and increasing integration are that they enable lower manufacturing cost as well as higher performance. Charge trapping memory is regarded as one of the most promising flash memory technologies as further down-scaling continues. In addition, more and more exploration is investigated with high-k dielectrics implemented in the charge trapping memory. The paper reviews the advanced research status concerning charge trapping memory with high-k dielectrics for the performance improvement. Application of high-k dielectric as charge trapping layer, blocking layer, and tunneling layer is comprehensively discussed accordingly.