DIRECT OBSERVATION OF THE DEFECT STRUCTURE OF POLYCRYSTALLINE DIAMONDBY SCANNING ELECTRON-MICROSCOPY

A method has been demonstrated to directly observe the surface crystal lography and defect structures in diamond films by scanning electron m icroscopy. Individual diamond crystals in the polycrystalline films ar e polished to a rms smoothness of less than 2 nm using iron metal at t emperatures in excess of 725-degrees-C. In the absence of topography, the detailed microstructure of the films can be characterized by secon dary electron imaging in a scanning electron microscope by charge-indu ced electron contrast which shows strong beam voltage dependence. It i s hypothesized that defects and grain boundaries form a connected path way in the film which has greater conductivity than the generally insu lating diamond and creates the charge-induced contrast.