Sequential deposition of diamond from sputtered carbon and atomic hydrogen

Abstract

The growth of diamond thin films on a scratched silicon crystal surface by a chemical-vapor deposition technique is reported. The substrate was bombarded by sputtered carbon from a graphite target in a helium dc glow discharge, and subsequently exposed to atomic hydrogen generated by a hot tungsten filament. The resulting diamond films were characterized by Raman spectroscopy and scanning electron microscopy. Deposited film quality and growth rate were studied as functions of carbon and atomic hydrogen exposure. An increase in growth rate of diamond was observed with atomic hydrogen exposure. We also observe that only the first monolayer of carbon deposited with each exposure appears to be utilized. These observations suggest that the diamond growth is a surface reaction. Further, calculations based upon the carbon utilization in traditional hot filament reactors indicate that a gas-phase reaction process can account for neither the growth rate nor the saturation behavior observed. Based on this work it is proposed that the growth of diamond films is governed by surface reactions, and that the necessity of gas-phase precursors can be precluded.