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The amorphous formation ability and the magnetic properties of Nd60Fe30xCoxAl10 (x 10, 15, 20 or 30) alloys in the containerless process were studied by the new gas jet flow type levitating process. The gas jet flow type levitating process enables solidification without any container wall by the inert gas jet. The samples were solidified at the cooling rate of around 100K/s. Then, the undercooling of samples exhibits high values (T 60{150K). From X-ray diffraction measurements, the Nd60Fe30xCoxAl10 samples exhibit a typical broad diffraction pattern for an amorphous structure. The DTA curves of x 10, 15 and 20 showed an exothermic peak due to the crystallization. That is, it was revealed that the Nd60Fe30xCoxAl10 samples formed bulk amorphous. Also, the coercivity is 1.6, 3.3 and 3.6 kOe for the Nd60Fe20Co10Al10, Nd60Fe15Co15Al10 and Nd60Fe10Co20Al10, respectively. From the thermomagnetic curves, the Curie temperature is determined to be 463, 482 and 482K for the Nd60Fe20Co10Al10, Nd60Fe15Co15Al10 and Nd60Fe10Co20Al10, respectively. In the M-H loops and the thermomagnetic curves, this difference between x 10 and x 15, 20 may depend on the microstructure. [doi:10.2320/matertrans.47.1568

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Aluminum-based high-permittivity (high-k) gate dielectrics and suitable metal electrodes were systematically designed for advanced SiC power metal-oxide-semiconductor field-effect transistors (MOSFETs). Although electron injection into alumina (Al2O3) was significantly suppressed by nitrogen incorporation (aluminum oxynitride: AlON), gate leakage current under negative gate bias and hole trapping into the dielectrics were observed. Adding hafnium into the AlON (HfAlON) was investigated to overcome these drawbacks, and an atomic layer deposition-based method for HfAlON was developed in terms of permittivity, energy bandgap, and hole conduction under negative stressing conditions. Consequently, the reliability of metal/high-k gate stacks under both positive and negative bias temperature stresses was improved by using an optimized HfAlON gate dielectric in combination with a high work-function TiN gate electrode. Thanks to the higher permittivity of HfAlON, peak transconductance was successfully enhanced up to 3.4 times with an acceptable reliability margin in the state-of-the-art trench SiC MOSFETs by implementing a TiN/HfAlON gate stack.

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