CHARACTERIZATION OF DIAMOND FILMS SYNTHESIZED ON SI FROM A GAS-PHASE IN MICROWAVE PLASMA BY SLOW POSITRONS

Variable-energy positrons were used as a nondestructive probe for diamond films synthesized on the Si substrate from a gas phase of a CH4/H2 mixture by microwave plasma chemical vapor deposition. The Doppler broadening of the annihilation photons was found to be strongly influenced by the concentration of CH4. The values of mean positron diffusion length in the diamond films were found to be decreased by increasing the concentration of CH4. The concentration of defects, C, was estimated as follows: 4×10-44×10-3. Apositronium (Ps) formationinavacancyclusterwasfoundfromtheanalysisoftheDopplerbroadeningprofiles, andtheintensityofPswasfoundtobeaffectedbyCH_4 and/orH_2 gastrappedinsuchdefects. TheresultsofthemeasurementsofRamanspectraarealsodiscussed. © 1990 The Japan Society of Applied Physics.