The effect of an electric field on the chemical vapour deposition of (100) diamond

The scanning tunnelling microscope (STM) has been used to modify surfaces with atomic resolution and has consequently been proposed as a tool for nanotechnology. Here we examine a process for deposition of (100) diamond under a localized electric field. We use ab initio quantum-chemistry techniques to investigate the effect of an electric field on the chemical vapour deposition of (100) diamond. The field approximates the field of an STM by using a point charge placed 15 Å above the surface to create a 0.64 V Å-1 field at the dimer. Our study explores the effect of this electric field on CH3 adsorption, and the dimer-opening and ring-closing steps of the Brenner-Garrison diamond CVD mechanism. CH3 adsorption is exothermic by 84 kcal mol-1 and is not affected by the electric field. The dimer-opening and ring-closing steps are sensitive to the applied field: the dimer-opening barrier is reduced from 9.6 to 6.0 kcal mol-1, while the barrier of the ring-closing step is reduced from 13.6 to 11.0 kcal mol-1. Our results indicate that the rate of CVD diamond growth can be enhanced by the application of an electric field, in agreement with experiment.