The nitride layers were prepared by direct thermal nitridation of 6H-SiC substrates at 1200-1570 C in a NH 3 atmosphere. The layer was characterized by using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman scattering spectroscopy. The thickness of the nitride layers prepared at lower than 1400 C was estimated to be less than 10 nm. The higher nitridation temperature resulted in the formation of a thicker surface layer. XPS measurement showed that the surface layer was composed of N, Si, C and O. Peaks corresponding to -Si 3 N 4 were detected in the Raman spectra and the XRD patterns of the sample prepared at higher than 1500 C, indicating the crystallization of the nitrided layer.

Chemically and thermally stable thin films of polyphthalocyanine were prepared by a simple evaporation-polymerization method. The rectifying characteristics of metal/semiconductor/ metal (MSM) type sandwich devices with the film were studied. A Schottky type device metal (Cu, Al, Ti)/polyphthalocyanine/Cu shows reproducible rectifying characteristics when Ti is selected as a counter electrode. The reproducibility is improved by pre-oxidation treatment of the surface of Cu substrate. Best electric parameters for the device are as follows: rectifying ratio = 14; threshold potential difference = 0,61 V; saturation current = 2,5 .A . cm -2 ; barrier height = 0,75 eV; diode ideality parameter = 4,23. Doping of five kinds of quinones [p-benzoquinone (p-BQ), tetrabromo-p-benzoquinone (pTBBQ) tetrachloro-p-benzoquinone (p-TCBQ)) tetrachloro-o-benzoquinone (oTCBQ) 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)] and 2,5-cyclohexadien-l,4-diylidenedimalodinitrile (TNCR) in thin films of polyphthalocyanine affected electrocharacteristics in some cases. The diode ideality parameter decreases to 2,17 at 0,90. 1 0-6 mol . cm-' of pTBBQ, and the rectifying ratio increases to about fourteen times by doping p-TBBQ and p-TCBQ. The doped device shows a rectifying response up to 1 kHz.

Nitrided layers were grown on a 4H-SiC(0001) by plasma nitridation method using NH 3 . Nitridation was enhanced with increasing RF power and with decreasing growth pressure. However, the exact capacitance-voltage (C-V) properties of the nitride layer/SiC interface could not be determined because of the leakage current. The SiO 2 film was deposited on the nitrided layer by thermal chemical vapor deposition method using tetraethoxysilane (TEOS) omit obtain an insulating film with sufficient thickness and an exact interface property. The interface state density D it was evaluated from C-V characteristics by the Terman method. It was indicated that D it near the mid gap of the TEOS oxide/nitride layer structure was higher than those of the TEOS-SiO 2 films and thermal oxide film. The D it of the oxide/nitride layer successfully decreased by post NH 3 annealing.

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