THERMAL-CONDUCTIVITY OF THIN DIAMOND FILMS GROWN FROM DC DISCHARGE

The in-plane thermal conductivity of thin polycrystalline diamond film s produced in a d.c. discharge system has been measured by a contactle ss technique of transient thermal grating. Diamond films of different qualities but of the same thickness (11 mu m) were deposited from CH4/ H-2 mixtures at methane contents ranging from 2% to 10%. The highest t hermal conductivity k=9.5 W cm(-1) K-1 was found for the sample synthe sized at the lowest CH4 concentration (2%), the value of k smoothly de creasing to 1.2 W cm(-1) K-1 with increasing methane content. The obta ined results are in good agreement with previous measurements on simil ar films performed by the mirage technique. A correlation of thermal c onductivity with film morphology and phase content analyzed by SEM and Raman spectroscopy is discussed.