Nucleation and growth of chemical vapor deposited diamond films

This research involves a study of the nucleation and growth processes during diamond chemical vapor deposition (CVD) via numerical modeling and simulations. Numerical models have been developed: (1) to examine the chemistry of the intermediate layer that forms at the interface between diamond and non-diamond substrate, (2) to understand the nucleation, size and structure of diamond phase carbon clusters on Si(111) substrates, (3) to study the morphological instabilities associated with diamond growth during chemical vapor deposition.;The chemistry of the intermediate layer that develops at the interface between diamond and non-diamond substrate during chemical vapor deposition is analyzed using a thermodynamic quasiequilibrium model. Substrates of Si, Mo, W, Ti, Ta, Fe and Ni are examined, and operating parameters such as the substrate temperature, reactor pressure, and CH;A theoretical study of the nucleation, size, and structure of diamond-phase carbon clusters on Si(111) substrates is presented. Silicon is chosen as the non-diamond substrate in this work as it is a common substrate material for diamond deposition. Molecular mechanics analysis has been utilized to predict energetically and entropically feasible pathways for nucleation of carbon clusters. Several mechanistic pathways for nucleation of carbon clusters are examined with ;The diamond CVD process has been examined theoretically and the morphological instabilities associated with the growth of diamond films have been investigated with a model based on the continuum species conservation equations coupled to surface reaction kinetics. An analytical model is developed to study the morphological instabilities of the diamond-gas interface during the diamond CVD process based on the linear and nonlinear perturbation theories. Linear stability analysis cannot be used to analyze the evolution of the unstable planar interface to a nonplanar cellular interface. Nonlinear analysis is carried out to study the growth behavior of an interface more accurately over a longer period of time. A two-dimensional numerical model describes the evolution of the gas-solid interface. The numerical and analytical models determine the critical parameters affecting the diamond deposition layer morphology. A dispersive relation is derived which relates the effects of species diffusive transport towards the growing interface, surface diffusion, surface tension, and geometrical factors with the stability of perturbations on the interface. (Abstract shortened by UMI.).