Surfaces of undoped and boron doped polycrystalline diamond films influenced by negative DC bias voltage

Abstract

The hydrogen ion bombardment is performed by applying a negative bias voltage to the substrate during 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]-oriented films after doping boron are investigated by scanning electron microscopy (SEM) and cathodoluminescent (CL) spectra. The absence of the band-A emission in the CL spectra means a low density of dislocation in the films. It is the first time that the peak at 741.5 nm and the broad peak at approximately 575 and 625 nm in the CL spectra were reduced efficiently after boron doping in (001) polycrystalline diamond films and to propose that these phenomena should be explained in simple terms with penetration of the lattice nets of the [001]-oriented faces model.