Variable-range-hopping through disl identified as the main off-state leakage m GaN vertical diodes on different substrates. of leakage current for vertical devices as dislocation density and electric field was der simulations, after careful calibration with ex literature data. Designed GaN vertical diode 2-4 orders of magnitude lower leakage supporting 3-5 times higher electric field, GaN lateral, Si and SiC devices.

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The effect of Zr on the microstructure, microchemistry and coercivity of Sm(CobalCu0.08Fe0. 10Zrx)8.5 (x = 0–0.10) magnets has been systematically investigated. The presence of Zr is responsible for the formation of the lamella structure. With increasing Zr content, a cellular-like structure gradually develops while the density of the lamella phase increases. A proper Zr content (0.015–0.060 at.%) is the key to form a complete and uniform cellular structure. Microchemistry data show that the Cu content in the cell boundaries in the magnet with 0.04 at.% Zr is higher than that with 0.015 at.% Zr, although both samples have similar microstructure morphologies. Higher coercivity is obtained in samples where the domain walls (DWs) are pinned at cell boundaries. For Zr-free or higher Zr samples, DWs nucleated at grain boundaries are responsible for the reduction in coercivity. During isothermal ageing, at a fixed Zr content, the coercivity is developed with increasing ageing time. These results clearly show that Zr plays an important role in the formation of a uniform cellular structure with the right microchemistry and that a critical amount of Zr is needed for the optimum magnetic properties.

The high magnetic anisotropic properties of L1 0 fct crystal structure (CuAu type, P4/mmm) make FePt thin films a promising candidate for next generation magnetic recording media. Elemental addition has proved to be an efficiency way to modify magnetic properties and microstructure of FePt materials [1][2][3][4]. Ti can be used to reduce the ordering temperature of FePt phase [5].In this paper, FePt/Ti multilayers were DC sputtered onto a Si (111) substrate. Post-annealing was carried out in a vacuum system at 800ºC. Both plan-view and cross-sectional TEM samples were prepared by ion milling. Conventional TEM and HRTEM were examined on a JEOL 2010 transmission electron microscope. STEM, EDXS and EFTEM were done on a JEOL 2010F transmission electron microscope. EFTEM images were obtained with a Gatan GIF imaging filter at a 25-eV slit width. The two-window ratio method was used to calculate the energy-filtered elemental mapping images. Oxford EDXS system and Inca software were used to collect and process STEM/EDS data.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.