Characterization of diamond films by core-level photoabsorption
Core level photoabsorption and Raman spectroscopies have been used to characterize both nanocrystalline and faceted, microcrystalline diamond thin films grown by microwave plasma chemical vapor deposition under a variety of conditions. Raman spectroscopy is perhaps the most commonly used method of characterizing diamond film quality, whereas photoabsorption typically requires a synchrotron radiation source and is much less commonly used. Both methods characterize the sp{sup 2} (graphitic)/sp{sup 3} (diamond) electronic bonding character of the films, but the photo-absorption measurement is much less sensitive to domain size than Raman spectroscopy. The Raman spectra measured using 632.8 nm light varied significantly, exhibiting sharp diamond phonon peaks for the faceted, large grain films, and no obvious diamond phonon peak for the nanocrystalline films. Raman spectra excited by 228.9 nm light exhibit a sharp diamond phonon peak for both nanocrystalline and large grain, faceted films. The C(1s) photo-absorption measurements show clear bulk diamond excitonic and sp{sup 3} features, with little evidence of sp{sup 2} character for all of the tested films. The difference between the measurement techniques can be attributed to the sensitivity of Raman spectroscopy to domain size and excitation wavelength, indicating that the use of Raman spectroscopy as the sole criterion for the assessment of diamond quality may be misleading for nanocrystalline films.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States); Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48; W-31109-ENG-38
- OSTI ID:
- 230361
- Report Number(s):
- ANL/CHM/CP--88512; CONF-960401--22; ON: DE96009411
- Country of Publication:
- United States
- Language:
- English
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