HIGH-RESOLUTION ELECTRON-ENERGY-LOSS SPECTROSCOPIC STUDY OF EPITAXIALLY GROWN DIAMOND (111) AND (100) SURFACES

Diamond (111) and (100) surfaces have been investigated by low-energy electron diffraction and high-resolution electron-energy-loss spectroscopy (HREELS). Samples were boron-doped semiconducting diamond surfaces grown homoepitaxially on natural diamond by microwave-plasma-assisted chemical-vapor deposition. A dipole-active C-H stretching vibration was observed at 352 meV (2839 cm(-1)) on the (111) surface and 363 meV (2928 cm(-1)) on the (100) surface. In the off-specular EELS spectra, two C-H stretching modes (352 and 361 meV) were clearly resolved on the (111) surface, while only one C-H stretching vibration was detected on the (100) surface. The two modes on the (111) surface are assigned to symmetric and asymmetric vibrations of CH3 species, respectively. This study clarifies hydrogen termination of the epitaxially grown diamond (111) and (100) surfaces in the forms of CH3 (methyl) and CH (monohydride) groups, respectively.