Diamond materials with enhanced heat conductivity

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Those of ordinary skill in the art will realize that the following description of the present invention is illustrative only and not in any way limiting.
Other embodiments of the invention will readily suggest themselves to such skilled persons.
According to the present invention, polycrystalline diamond materials and processes for making the films are disclosed.
Composite diamond/non-diamond films are also disclosed herein.
The diamond and composite materials produced by the present invention have thermal conductivity greater than 17 watts/cm/K measured at about 20.
degree.
C.
One of the underlying necessary conditions for high-thermal-conductivity diamond is a high degree of structural perfection, as disclosed by Raman spectroscopy.
It has been discovered that there is a correspondence between photoluminescence and Raman spectroscopy data and structural characteristics of diamond materials.
According to the present invention, the required structural perfection of diamond films may be identified by specifying quantitative limits on certain Raman and photoluminescence features.
A common means of nondestructive analysis of diamond films is the use of Raman spectroscopy.
This is an optical technique in which a fixed energy (wavelength) of illumination is directed onto a sample to be analyzed.
Raman scattering in the sample volume produces light with energy different from the excitation energy by either the sum or the difference of phonon energy levels in the solid being probed and the excitation energy.
One- and two- phonon Raman scattering effects are known, in which the Raman signals are displaced from the excitation energy by .
+-.
1 or .
+-.
2 phonon energy levels.
Phonon energy levels in covalent solids like diamond are sensitive to the details of chemical bonding.
Thus, diamond-bonded carbon produces a Raman shift (energy displacement) of about 1332.
5 cm.
sup.
-1 (a unit of energy), while graphitically-bonded carbon produces a shift of about 1550 cm