Direct observation of the defect structure of polycrystalline diamond by scanning electron microscopy

A method has been demonstrated to directly observe the surface crystallography and defect structures in diamond films by scanning electron microscopy. Individual diamond crystals in the polycrystalline films are polished to a rms smoothness of less than 2 nm using iron metal at temperatures in excess of 725 °C. In the absence of topography, the detailed microstructure of the films can be characterized by secondary electron imaging in a scanning electron microscope by charge-induced electron contrast which shows strong beam voltage dependence. It is hypothesized that defects and grain boundaries form a connected pathway in the film which has greater conductivity than the generally insulating diamond and creates the charge-induced contrast.