Abstract :
A series of 4H-silicon carbide SiC.epilayers grown on 4H-SiC substrates by low pressure chemical vapor deposition
LPCVD.with different silane SiH4.to propane C3H8.gas flow ratios were studied by angle resolved X-ray
photoelectron spectroscopy ARXPS.and atomic force microscopy AFM.. ARXPS revealed that the surfaces of the samples
consisted of elemental Si, Si oxides SiO2 and SiOx where x-2.and unreacted C–H species, in addition to the
stoichiometric SiC compound. Small amounts of elemental Si were also detected within the 4H-SiC epilayers. The surface
thickness of the C–H overlayer showed a positive correlation with the C3H8 source flow, and comprised largely of
unreacted C3H8 or its intermediate products such as C2H2 and C2H4. This C–H overlayer had an rms roughness of
0.4"0.1 nm as determined by AFM. The roughness was independent of the Si:C source ratio. AFM analyses revealed
numerous micro-scratches which were the polishing marks on the 4H-SiC substrate copied by the epilayers. q1998 Elsevier
Science B.V.
