Scanning tunneling microscopy study of antiphase boundaries on the (001) surface of homoepitaxial diamond films

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. Surface morphology showed a dimer-type 2X1 reconstructed surface structure with antiphase boundaries on each domain. Single step edges with inequivalent shape were along the (110) directions. 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. To our knowledge, the antiphase boundaries are to be observed for the first time on a homoepitaxially grown diamond (001) surface. Atomic images revealed that two different types of 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.