Nano-structure of transition-metal (Ti, Ni)/SiC system: photo-emission electron microscopy and soft X-ray fluorescence spectroscopy

We have studied nano-structure of transition-metal film (Ti, Ni)/SiC (substrate) contact systems by using a photo-emission electron microscopy (PEEM) and a soft X-ray fluorescence spectroscopy (SXFS). The PEEM and SXFS studies using light sources of a Hg lamp and a synchrotron radiation, respectively, have been applied to a nondestructive buried interface analyses and a surface nano-structure study for a thin-film (Ti, Ni)/substrate (3C-, 4H-SiC) contact system. A PEEM image after a heat-treatment of Ti (10 nm)/3C-SiC contact system at 800 deg. C has shown small clusters of 2-3 μm in diameter on a specimen surface. On the other hand, a PEEM image of Ni (4 nm)/3C-SiC contact system has shown uniform surface morphology with increasing annealing-temperature up to 650 deg. C. Therefore, Ti (ultra thin film)/SiC (substrate) system is expected to be a good candidate to form nano-structure on top, whereas Ni is suitable for uniform contact at elevated temperatures. In SXFS, we have studied in-depth structure through the electronic states from deep inside to near surface region by changing an angle of incident light against a sample surface. Valence band electronic structure in the top thin-film for Ti/4H-SiC contact system is considered to be a combination of Ti-silicide and -carbide and/or graphite from SXFS study. On the other hand, it is the case that Ni/4H-SiC contact system is composed of Ni-silicide with crystallized graphite due to a heat-treatment until 950 deg. C