Structural studies of diamond thin films grown from dc arc plasma

Abstract

Diamond thin films grown from a dc-arc discharge in CH 4 ͞H 2 mixtures on Si wafers were examined by transmission electron microscopy and Raman spectroscopy. This deposition method provides good diamond crystallinity at high CH 4 concentrations (3% -9%). Seeding the substrate with 5 nm diamond particles at a density of 2 3 10 12 cm 21 followed by argon laser irradiation to reduce their agglomeration gives, just after starting deposition, a density of growth centers of 10 10 cm 22 . At 3% CH 4 concentration the film grows with almost perfect crystallites. Richer CH 4 mixtures (5% and 9%) produce crystallites with twins and stacking faults. An amorphous 20 -70 nm SiC interlayer is present at these CH 4 concentrations, which was not observed at 3% CH 4 . Amorphous sp 3 -and sp 2 -bonded carbon was detected by Raman spectroscopy at all CH 4 concentrations and correlated with TEM data.

Structural Aspects of CVD Diamond Wafers Grown at Different Hydrogen Flow Rates

“…(iv) As it appeared from electron microscopy observations, reduced flow rates of the reactant gases are equivalent, in many respects, to the case of enhanced methane content in the gas mixture, which results in an increased density of defects and the appearance of amorphous material in the diamond films [7]. Thus, a hydrocarbon supersaturation in the plasma, which possibly occurs at slow gas exchanges in the reaction chamber, might be the reason for the degradation of the diamond film quality grown under such conditions.…”

Effect of film thickness on the temperature dependence of thermal conductivity for diamond/BeO composites

“…Increasing crystal sizes and diminishing of grain boundaries are observed, also depicted in the picture for better view. It has been proven that impurities like amorphous and graphitic phases mainly accumulate at grain boundaries [25][26][27]. Also, the regular defects including dislocations and stacking faults had been proved to be located preferentially near grain boundaries [23,28,29].…”