The nucleation and growth of large area, highly oriented diamond films on silicon substrates

Highly oriented diamond films can play an important role in replacing single crystal diamond for their use as substrates in active electronic devices. However, for practical applications, large, homogenous films with low defect densities are required. The focus of our investigations is the nucleation of highly oriented diamond on (001) silicon via Bias Enhanced Nucleation (BEN) over large areas. A modified BEN process using repetitive pulse bias 'RP-BEN' was developed, resulting in an area of oriented nucleation of up to 30 cm(2). The density of azimuthally oriented diamond seeds was measured by scanning electron microscopy (SEM) images and found to be 8 x 10(8) cm(-2) with only 30% variation over the whole deposition area. After the nucleation, a microwave plasma assisted chemical vapor deposition (MPACVD) resulted in highly oriented and [100] textured diamond films. X-ray diffraction (XRD) measurements of the {111} diamond peak, for a 60-mu m-thick film, showed azimuthally misorientations (FWHM) of 2.8 degrees for the tilt and 5.5 degrees for the rotation. Raman spectroscopy was used to evaluate the radial distribution of the phase purity within the films. Introducing a final growth step with a low nitrogen concentration in the gas phase yielded a significant decrease in nitrogen incorporation in the films while maintaining the morphology. Elastic recoil detection (ERD) revealed impurity concentrations in the surface layer of 1.4 ppm for the N/C ratio and 210 ppm for the H/C ratio. (C) 1998 Elsevier Science S.A.