Thermal Wave Measurement of Isotopic Effects in Polycrystalline and Bulk DiamondMaterials

摘要

The thermal wave technique and microfocus Raman spectroscopy are utilized tomeasure the thermal diffusivity and the relative quality of synthetic and natural single crystal diamond as well as thin polycrystalline diamond films deposited on various substrates. For natural isotopic composition ( 1% 13C) single crystal diamonds, we have obtained thermal conductivities of 22 W/cm-K, in excellent agreement with measured values found in the literature of natural diamonds. For isotopically enriched (0.1%, 0.5%), type IIA, single crystal diamonds, we have obtained room temperature thermal conductivities of 33 (0.1%) and 26 (0.5% W/cm-K. These are the highest observed room-temperature thermal conductivities of any naturally occurring or previously synthesized solid. We also observe that the laser damage threshold at 193nm for the isotopically enriched (0.1%) crystal is more than an order of magnitude higher than that of the natural diamond crystals. For polycrystalline diamond films, the diffusivity is inversely correlated with the estimated graphitic percentage, which for high quality films ( 12W/cm-K) is five percent or less.