Scanning Tunneling Microscopy of Chemical Vapor Deposition Diamond Film Growth on Highly Oriented Pyrolytic Graphite and Silicon

Abstract

We report scanning tunneling microscopy (STM) studies of chemical vapor deposition (CVD) diamond film growth on highly oriented pyrolytic graphite (HOPG) and Si. The films were grown using hot-tungsten filament CVD. Using conditions typical for CVD diamond growth, we find that HOPG is etched by atomic hydrogen such that oriented hexagonal pits 50–5,000 Å in diameter are produced on the surface. Diamond crystallites are observed to nucleate on the walls of these pits and not on the smooth sp ² bonded parts of the surface. At lower sample temperatures, HOPG is etched such that large circular pits approximately 10,000 Å in diameter and 7 Å deep are produced. Nanoscale linear structures, which we conjecture are hydrocarbon chains, are observed in these pits. These structures orient themselves when a voltage of 10 V is applied to the tip. The initial stages of diamond film growth on Si were studied. Polycrystalline films on Si approximately 2 µ thick were imaged in air from a micron to atomic resolution scale. The micrometer scale images show that these films consist of diamond crystallites with (100) or (111) oriented faces. Atomic resolution images of the (100) surface in air showed a 2 × 1 dimer reconstruction with a distance between dimer rows of approximately 5.1 Å.