Development of Photodeposited Diamond Films

This document details a study of the fundamental physical and chemical processes occuring in hot filament and laser assisted synthetic diamond CVD processes. The chemical model developed in this program permits a detailed analysis of previous investigations. This model suggests that several factors will limit the attainable purity and utility of synthetic diamonds grown by plasma or hot filament CVD techniques. A diamond deposition process based upon selective laser production of the chemical species which give rise to the films is described. This technique holds the promise of growing essentially pure diamond at rates comparable to existing schemes, and should permit co-deposition of selected dopant species to make novel new optic and electro-optic devices. An experimental diamond CVD reactor has been designed, developed and tested to provide experimental verification of the model. The reactor has been run in two modes of operation a hot filament CVD mode, and a laser-assisted hot filament mode. Films deposited in the hot filament mode of operation exhibit the physical characteristics and growth behavior expected for synthetic diamond films. The observed growth kinetics agree with predictions based upon the chemical model developed here. A study based upon a laser-assisted hot filament diamond CVD process suggests that the laser process results in an enhancement of the rate of film growth, although the extent of this enhancement was limited by the available laser power. Further investigation using greater laser powers will be required to confirm this result and expand upon the results.