Studies of 4H-SiC(0001)Si(root 3 x root 3) and (0001)C(3 x 3) surfaces andtheir metallization process by Ni using STM, AES and LEED

Several methods have been tried to prepare clean surfaces of 4H-SiC(0001)Si and C, whose surface atomic, or electronic, structures have been studied b y LEED (low energy electron diffraction) STM (scanning tunneling microscopy ) and AES (Auger electron spectroscopy). Some sequential chemical treatment s, for example, agitation in an organic solvent and dipping in HF solution, followed by the heating of a SiC wafer in UHV (ultrahigh vacuum, below 10( -7) Pa) at 950 degreesC, gave either a root3 x root3 or 3 x 3 superstructur e, observed by LEED (low energy electron diffraction), for the SiC(0001) Si or C surface, respectively. An elongated NH4F treatment followed by a heat treatment in UHV at similar to 950 degreesC gave a rather flat region to b e investigated by STM, where a root3 x root3 superstructure for the SiC(000 1) Si surface has been observed. In the case of metal (Ni) atom deposition on SiC(0001) Si(root3 x root3) and (0001)C(3 x 3) surfaces, AES and LEED an alysis have clarified that deposited metal atoms form islands up to similar to 5 Angstrom. However, Ni atoms dispersed uniformly at the very beginning of the deposition, which means that the Ni overlayer piles up in layer fol lowed by island growth mode.