Fine-structure study on first-order diamond Raman line of CVD diamond particles

Micro-Raman spectroscopy was employed to characterize the fine structure of the first-order Raman line and the stress distribution of overgrown [111] and [100] CVD diamond particles, For overgrowth on [100] particles original ly underlying strain, peak splitting is observed, which indicates that the original strain is difficult to eliminate using the overgrowth process. For overgrowth on unstrained edgeless diamond powder, very different diamond R aman peaks consisting of a single Lorentzian peak in the spectra of the (10 0) surface of the [100] particle and two Lorentzian peaks in the spectra of the (111) surface of the [111] particle were found. The study on the relat ionship between the focus position on the growth surface and fitting parame ters revealed that the peak position, from which the magnitude of stress ca n be estimated, and FWHM of the sharp component of the [111] particle and t he peak of the [100] particle changed slightly along the direction from par ticle center to edge, while the broad component of the [111] particle showe d random variation. The broad peak in the spectra of the [111] particle was suggested to be sensitive to structure defects and impurities. After overg rowth, the internal powder strain became compressive strain. Anti-Stokes an d Stokes lines showed different symmetries and laser irradiation temperatur e was near room temperature in this study.