Raman spectra have been measured on a variety of
natural and synthetic diamonds, diamond-like carbons, and
graphitic carbons in order to test the applicability of
Raman spectroscopy as a characterization tool for synthetic
diamonds. The diamond line is a reliable indicator of the
presence of diamond and with a microfocus Raman spectrometer,
the diamond signature can be observed from
grain to grain on a deposited film. Graphitic carbon has a
distinctly different Raman spectrum which is more intense
than the diamond spectrum, allowing a small amount of
graphitic carbon to be recognized in diamond films. Many
of the investigations of the relationship between measured
TABLE IV. Stress-induced Raman lineshifts in diamond films.
DIAMOND ON ALUMINA
NATURAL DIAMOND
1332
1345
500 7S0 1000 1250 1500 1750
WAVENUMBER
FIG. 10. Raman line shift for diamond film on alumina substrate. Natural
diamond spectrum is given for reference.
Substrate
Alumina
Tungsten carbide
SiO2 glass
SiAlON
v (cm"1)
1345
1328
1327
1328
1328
1337
1336
v (cm"1)
+ 13
- 4
- 5
- 4
- 4
+ 5
+ 4
Stress (GPa)
+ 5.5
-1.7
- 2 .1
-1.7
-1.7
+2.1
+ 1.7
spectral parameters and the structure state of graphitic carbon
have been evaluated.