Computer simulation of diamond film growth by chemical vapor deposition using Monte Carlo method

Scope and method of study. A kinetic Monte Carlo method has been applied to simulate low-pressure diamond film growth from a C (111) substrate via acetylene and hydrogen vapor deposition. Two different sizes of substrates (200 and 512 carbons) were simulated, respectively. Gas phase acetylene and hydrogen were moved in a directed random walk towards the substrate. Acetylene-substrate reactions consisted of breaking the {dollar}Cequiv C{dollar} bond to produce a {dollar}C = C{dollar} bond, and a new {dollar}Csb{lcub}s{rcub} - C{dollar} bond along the direction of the unpaired bond of the surface carbon, {dollar}Csb{lcub}s{rcub}{dollar}. During each KMC pass through the system adsorbed {dollar}Csb{lcub}s{rcub} - C{dollar} molecules were also given an opportunity to desorb or to relax through random rotations about {dollar}Csb{lcub}s{rcub} - C{dollar} bonds. Interactions are governed by a semiempirical interatomic potential energy function proposed by Brenner.; Finding and conclusions. We find that acetylene binding to a clean C (111) surface is favored in this Monte Carlo process, but adsorption of a second {dollar}Csb2Hsb2{dollar} is not likely until the neighborhood around the site for the second-layer adsorption contains a sufficient number of first-layer adsorbed molecules. This property of the potential energy surface is responsible for layer-by-layer growth of the film. We also find that the simulated surface is somewhat rougher tkan diamond surfaces studied by atomic force microscopy. This suggests a need to include methyl radical in future simulation models.