Surface topography and nucleation of chemical vapor deposition diamond films on silicon by scanning tunneling microscopy

Abstract

The surface topography of diamond thin films deposited on silicon have been charted by scanning tunneling microscopy (STM). This study addresses the initial nucleation of diamond growth on Si, and the faceted structure of the diamond films. The results were obtained from an in-air STM system with tunneling currents between 0.2 and 3 nA. For studies of the diamond nucleation, samples were prepared by timed growth up to 60 min in a microwave plasma chemical vapor deposition (CVD) system. Diamond films with thicknesses in the 1–2 μm range were prepared by hot-filament CVD and examined by STM to determine the morphology of the diamond growth surface. The presence of diamond was verified by Raman spectroscopy. The STM images show that the surface is uniformly affected in the first 30 min of growth and diamond nuclei are identified after 60 min of growth. The thick films showed topography with facets on the surface similar to those seen from scanning electron microscopy results. The surface of these facets have been examined as well as the area between the facets. Elongated ridge structures are observed between different facets on the surface.