THERMAL-EXPANSION OF POLYCRYSTALLINE DIAMOND PRODUCED BY CHEMICAL-VAPOR-DEPOSITION

The in-plane thermal expansion of thick freestanding polycrystalline diamond films produced by hot filament chemical vapor deposition was measured by dilatometry. Measurements were obtained from two different diamond wafers over a temperature range of -200 to +800-degree-C. Within experimental error of the measurements, values agree with those reported for natural single-crystal diamond. Quantification of the thermal expansion of chemically vapor deposited (CVD) diamond is important for determining thermal stresses which will be encountered during deposition of diamond on various substrate materials and during use of diamond in various applications.