Correlation of the Raman spectra with the thermal conductivity of a set ofdiamond wafers prepared by chemical vapor deposition

Raman spectroscopy, at laser excitation wavelengths of 514.5, 785, and 1064 nm, is used to study a set of chemical-vapor-deposited (CVD) diamond wafer s of known thermal conductivity kappa. The in-plane thermal conductivity (a t 25 degreesC) of the diamond wafers ranges from 4 to 22 W cm(-1) K-1 and r epresents a wide range of diamond quality. The spectra were obtained from b oth macro/micro- sampling measurements, examining the top and bottom wafer surface, as well as wafer cross-sections. Discussed are the peak positions and linewidths of the Raman bands and their relation to sp(3)-bonded diamon d and sp(2)-bonded carbon in the context of diamond quality and perfection, and the effects of wafer heterogeneities. The detailed analysis of the Ram an spectra provides a robust correlation with the room-temperature bulk (or macroscopic) thermal conductivity of these samples. The correlation is mad e through the determination of the band area ratios of the diamond Raman li ne at 1333 cm(-1) to that of the 1550 cm(-1) band characteristic of nondiam ond carbon impurities. This dependence is most pronounced for the Fourier-t ransform Raman data obtained with infrared excitation at 1064 nm, due to re sonance enhancement, and therefore allows the detection of carbon impuritie s, especially for high-quality CVD diamond.