The dynamic control of the templates in selectivity growth from their isomers and the growth mechanism of CVD diamond

The key role of templates in the process of large-scale growth of ordered metastable phase and that of selectivity growth from their isomers with approximately equal free energy have been emphasized. Considering the rational elements in the existing models, the dynamics and thermodynamics theory for the growth process of diamond films have been given: 1) The chemical potential of carbon atoms is higher in the state of hydrocarbon gases than in the solid state. The carbon atoms in hydrocarbon gases may drop down to graphite or diamond surface that has a lower chemical potential. 2) The gas-state carbon atoms may change into the solid state through surface reactions. 3) The effect of surface of the template is a major factor for controlling the way of conversion of the gas-state carbon atoms. The different surfaces (surfaces with different orientations of graphite and diamond) can choose the different structure and energy state of the carbon atoms dropped onto them.4) Therefore, several kinds of different and independent surface reaction processes can occur at different sites of the substrate. These reactions correspond to the growths on different surfaces; 5) The orientation and velocity of these surface reactions are affected by the thermodynamic factors of neighboring surfaces. The direction of interaction determines whether growth or etching occurs for certain crystal surface. Growth of diamond and etching of graphite may be realized in a special range of temperature, of pressu re, of flow ratio of different gases. 6) The critical condition of nucleation wa s determined by the thermodynamic conditions such as local crystal lattice struc ture of the substrate, bonding structure, the gas temperature on the substrate s urface, pressure, the fractional pressure of different kinds of gases, and so on . 7) The plasma system that has energy exchange with the surroundings, and a ser ies of chemical reactions that occur in the gas phase can only provide the requi red non-equilibrium thermodynamic and chemical conditions to keep the growth of certain solid phase surface. The surfaces of diamond and graphite have the chara cter of template, they will dominate the epitaxy pattern of themselves. Heteroge neous substrates have certain local microstructure to play the role of a local t emplate for new phase nucleation. Different local microstructures caused by diff erent substrates, processing method and different chemical conditions will deter mine the orientation character,of the film.