N.А. Lvova, О.V. Ponomarev, A.I. Ryazanova
Moscow Institute of Physics and Technology (State University), Russian Federation
pp. 8 - 11
Keywords: C(100)-(2×1) diamond surface, point defects, plasma etching, quantum-chemical modeling
Diamond is a material comprising a number of unique properties. Some properties of diamond are of particular interest, namely: high thermal conductivity, high refractive index, transparency in a wide range of wavelengths, chemical inertness, and high hardness. Various applications of synthetic diamond in numerous areas of high technology often require a considerable effort in preparing a perfect surface. Another important target is to provide a surface relief structure with desired geometrical characteristics. Currently, a promising method of preparing a diamond surface is its reactive ion plasma etching (RIE) in gas mixtures containing hydrogen and oxygen atoms [1-3]. This method involves an interaction of the active particles with the surface, and this type of impact is inevitably accompanied by a significant number of defects. However, the mechanisms of chemical interaction between the hydrogen and oxygen atoms and H- and O-containing molecules and fragments with the point and line defects on the diamond surface remain largely underinvestigated. In this paper, we present the results of quantum-chemical simulation of the hydrogen and oxygen atoms interaction with a number of point defects on the C(100) and C(111) diamond surfaces. We applied the approach developed earlier in [4-7]. We used the СmHk clusters as model objects to simulate the reconstructed C(100)-2×1, C(111)-2×1 diamond surfaces. Simulation of mono- and divacancies, adatoms, and steps was carried out by removal or adding of one or more atoms in the central parts of the clusters. We calculated the cluster energy, atomic bond orders, population of the atomic orbitals, molecular and localized orbitals. We provide a comparison between the processes of H and O atoms interaction with an ordered and defect cluster surface. We investigated the interactions of hydrogen and oxygen atoms and H- and O-containing fragments with different types of surface defects. Preliminary calculations indicate a possibility of smoothing out the diamond surface when the hydrocarbon radicals are adsorbed from the gas mixture. This result is consistent with the experimental data . The results can be used to analyze the physical and chemical processes on the diamond surface during reactive ion etching using hydrogen- and oxygen-based plasma.