Accession Number:

ADA270876

Title:

Pressure and Temperature Effects on the Kinetics and Quality of Diamond Films

Descriptive Note:

Technical rept.,

Corporate Author:

GENERAL MOTORS RESEARCH LABS WARREN MI PHYSICAL CHEMISTRY DEPT

Personal Author(s):

Report Date:

1993-09-27

Pagination or Media Count:

35.0

Abstract:

The first measurements of the effects of pressure on the kinetics and quality of diamond films grown with hot filament chemical vapor deposition are reported. Pressure affects growth kinetics largely because it affects heat transfer between the filament and the substrate and because it affects transport of precursors to the growing surface. H and CH3 concentrations at the growth surfaces are determined with our recombination enthalpy technique combined with appropriate transport analyses. The growth rate rises and then falls with increasing pressure, although there is a saturation in the concentration of CH3 and atomic H at the surface. The fall in-growth rate at higher pressure is explained with our chemical kinetics model as due to an increase in substrate temperature at higher pressures. Since the rate of thermal desorption of the CH3 precursor increases more rapidly with temperature than the competing rate of its incorporation, and since these two rates are comparable, higher substrate temperatures lower incorporation rates, and the growth rate decreases.

Subject Categories:

  • Physical Chemistry
  • Coatings, Colorants and Finishes
  • Crystallography
  • Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE