Study of antiphase boundaries and local 3x1 configuration on the (001) surface of homoepitaxial diamond films by scanning tunneling microscopy

Homoepitaxial diamond films have been studied using scanning tunneling microscopy. Boron-doped films were grown on diamond (001) substrates by microwave plasma-assisted chemical vapor deposition. Atomic resolution scanning tunneling microscopy (STM) images showed a dimer-type 2 x 1 reconstructed surface structure and features such as steps, kinks and terraces. Single steps where dimer rows on the upper terrace are normal to the step edge are ragged and the steps where dimer rows are parallel to the step edge are straight, indicating that the steps have different formation energies. The double-domain surface structure observed with STM was in agreement with low-energy electron diffraction pattern. Atomic images revealed two different types of antiphase boundary on the diamond (001) surface. These antiphase boundaries run parallel to or perpendicular to the dimer rows where dimer rows shift by only one lattice constant of the diamond (001) surface. We found that single dimer rows preferentially extended along an antiphase boundary. Local 3 x 1 configurations have been observed on homoepitaxially grown diamond (001) surface.