COMPARISON OF THERMAL CONDUCTIVITIES ON ABRADED AND UNTREATED CVD-DIAMOND OBTAINED BY SCANNING THERMAL MICROSCOPY

Diamond materials have become progressively significant in the fabrication of heat sinks for power devices and lasers. To investigate the influence of polishing on CVD-Diamond, the surfaces of <100> and <110> coatings were analyzed, after a first abrasive treatment on a 30μm diamond grit by scanning thermal microscopy based on a resistive platinum-probe. This technique describes in first order approximation the heat transfer of a metal-diamond interface. Through this method it was possible to diagnose a relevant reduction in thermal conductivity by a harsh sample preparation depending on the crystal orientation. The thermal conductivity of as deposited <100> diamond was measured at 1290 W/mK and was reduced to 250 W/mK. The thermal conductivity of as deposited <110> diamond was determined at 1780 W/mK whereas the same diamond surface, but abraded, shows a thermal conductivity of just 460 W/mK. Additionally the received images which represents the thermal conductivity qualitatively bring forward micro structures like e.g. grain boundaries.