Tadashi Tomikawa

Diamond(001) single‐domain 2×1 surface grown by chemical vapor deposition

Diamond homoepitaxial films were grown on an off‐angle (001) substrate with a misorientation of 4.3° toward the [110] direction by microwave plasma‐assisted chemical vapor deposition from a methane‐hydrogen gas mixture. The single domain 2×1 surface was observed by low‐energy electron diffraction (LEED) and scanning tunneling microscopy, after growth with methane concentration of 2%. With a methane concentration of 6%, the LEED superstructure spot intensity from another domain increased, suggesting a higher rate of two‐dimensional nucleation.

Diamond homoepitaxial growth on (111) substrate investigated by scanning tunneling microscope

Epitaxial films were grown on diamond(111) substrates by microwave‐plasma‐assisted chemical vapor deposition, and their surfaces were studied by scanning tunneling microscope (STM). STM images with atomic order resolution were obtained, and showed 1×1 periodicity, which was also observed by low‐energy electron diffraction. 〈112〉 single bilayer steps, 〈112〉 single bilayer steps, and 〈112〉 double bilayer steps were observed, and the majority of the steps were found to be of the first type. Steps were found to be very straight in the atomic scale, and there were suggestions of the incorporation of carbon atoms at the kinks. Even a small island with a nanometer order size showed a triangular shape surrounded by three 〈112〉 single bilayer steps.

Cross-Sectional Transmission Electron Microscopy Observations and Selected-Area Electron Diffractions of Interfaces of Epitaxially Grown Diamond Thin Films on Cubic Boron Nitride Substrates

Diamond thin films grown from low-pressure methane-hydrogen gas mixture utilizing microwave plasma-enhanced chemical vapor deposition (CVD) on sintered polycrystalline cubic boron nitride (c-BN) substrates were examined by conventional and high-resolution transmission electron microscopy (TEM) techniques and also by the selected-area transmission electron diffraction (SATED) technique. On different planes of c-BN, such as (311), (310) and (211), epitaxial growth of diamond films was confirmed. The dislocations correspond to the mismatching of the lattice constants of diamond and c-BN were observed. One dislocation appeared per 82 to 84 diamond lattice planes. Due to the small grain size of the c-BN polycrystalline substrate, other defects, such as micro-twins, slips and stacking faults, were not observed at the interfaces in this investigation.