Effects of hydrogen ion bombardment and boron doping on (001) polycrystalline diamond films

Hydrogen ion bombardment was carried out by applying a negative bias voltage to the substrate during a microwave plasma chemical vapor deposition process, using only hydrogen as reactant gas. The size of (001) faces increases after hydrogen ion etching while other grains are etched off. The surfaces of [001] directionally oriented films after boron doping were investigated by scanning electron microscopy (SEM) and cathodoluminescent (CL) spectra. The absence of the band-A emission in the CL spectra indicates a low density of dislocations in the films. It is the first indication that the peak at 741.5 nm and the broad peak at around 575 and 625 nm in the CL spectra are reduced efficiently after boron doping in (001) polycrystalline diamond films. We propose that these phenomena could be explained in simple terms by penetration or adsorption through the lattice nets of the [001] directionally oriented surfaces model.