Graphitization of 6H-SiC(000(1)over-bar) surface by scanning tunneling microscopy

The surface structures of the carbon-terminated 6H-SiC(000 (1) over bar) surface are investigated during annealing at elevated temperatures up to 2400degreesC in ultrahigh vacuum by scanning tunneling microscopy and Auger electron spectroscopy. The graphitization of the 6H-SiC(0001) surface occurs in three stages; the first stage at 1100-1400degreesC, the second stage at 1400-1600degreesC and the third stage above 1600degreesC. Small particle-like features 1-3 nm in size with the atomic structure of carbon during graphitization are observed on the surface in the first stage. Flat terraces with the (6 x 6) reconstruction of 6H-SiC and the well-known triangular structure of graphite are observed on the surface in the second stage. Small graphitic nanoparticles 2-10 nm in size with the ringlike (root3 x root3)R30degrees. superstructure of graphite are observed on the surface in the third stage. The graphitization process on the 6H-SiC(000 (1) over bar) surface at elevated temperatures is discussed.