Spatial distribution of thermal conductivity of diamond wafers as measured by laser flash technique

摘要

Thermal conductivity perpendicularly to diamond film surface was measured using a laser flash technique. Polycrystalline diamond wafers of up to 500 microns thickness and 2.25 inch diameter were produced in microwave plasma at different deposition conditions. Thermal conductivity (TC) was determined from heat propagation time across the wafer after short pulse of a Nd:YAG laser absorbed at sample surface. Distributions of TC along wafer radius were measured with 1 mm spatial resolution, they correlate to optical absorption, Raman diamond peak width and amorphous carbon concentration in the material. The best TC values of 18 W/cmK were measured for selected samples.