Growth of diamond by means of first-principles calculations

Abstract

Radical attack and recombination are thought to play an important role in the atomicscale mechanisms driving the growth of diamond. Unfortunately, accurate ab-initio calculations of the growth mechanisms are scarce. This work presents an analysis of growth-related reactions, including the ones involving hydrogen and methyl radicals, on (100), (111) and (113) H-passivated diamond surface. The reactions investigated here include the migrations of different species. In addition, the reactions between the intermediate growth steps of the nucleation (including some etching mechanisms) are characterised through their reaction rate coefficients. The (climbing) nudged elastic band method is used to identify the minimum energy path of the reactions, which reveals either a tight or a loose transition state depending on the presence or absence of an energy barrier. Following the determination of the energy profile a given reaction, the vibrational spectra of its reactants, products and transition state is computed to derive its reaction rate coefficient by means of (variational) transition state theory calculations. These temperature- and pressuredependent reaction rate coefficient have great potential: using multi-scale methods (e.g., kinetic Monte-Carlo), they provide insights into the best conditions to grow single crystal diamond. Temperature, pressure and radical densities in the reactor influence both the rate and quality of the growth, and the versatility of the results presented herein allows to account for these factors. The approach used in this work can be generalised to any crystallographic orientation of diamond, and even to other semiconductor surfaces.