THE PREPARATION AND CHARACTERIZATION OF LOW SURFACE-ROUGHNESS (111) AND (100) NATURAL DIAMONDS BY HYDROGEN PLASMA

Natural doped (100) and (111) diamond surfaces were polished in a hydr ogen plasma at 870 degrees C and 40 mbar and analyzed by AFM, LEED and X-ray photoelectron diffraction (XPD). The initial surface roughness of 7 nm (rms) is decreased to 1 nm on the (111) surface and a 2 X 1 LE ED pattern is observed after annealing at 1000 degrees. After etching the (100) surface has a roughness of 0.8 nm and shows a sharp 2 X 1 LE ED pattern which is even stable in air without annealing. XPD measurem ents indicate that the quality of the top surface layer (30 Angstrom) is increased considerably by the etching and annealing process. Exposi ng the surfaces to atomic hydrogen produced by a heated filament leads to an increase of the surface roughness comparable to what was observ ed on the as received sample. The often reported 1 X 1 reconstruction seems to be a consequence of a large surface roughness and is absent o n smooth surfaces.