Atomic and Electronic Structures of Grain Boundary in Chemical Vapor Deposited Diamond thin Film

Abstract

High resolution electron microscopy and electron energy-loss spectrometry were used to investigate both atomic and electronic structures of grain boundaries in diamond thin films grown by chemical vapor deposition The atomic structures of {112}Σ3 and {114}∑9 <110> tilt boundaries in diamond show different features from those in other diamond structure semiconductors. The electron energy-loss spectra recorded from the grain boundary regions show extra intensity near the energy-loss corresponding to carbon Is-to-π* transition, as compared to the spectra recorded from neighboring crystalline regions. This gives the evidence that the dangling bonds are not fully reconstructed along <110> direction in the boundary structure. Atomic models are constructed for these boundaries with the presence of non-tetracoordinated atoms The stability of the boundary structure is explained by the π-like bonding between the nontetracoordinated atoms.