Characterization of Diamond Films Synthesized on Si from a Gas Phase in Microwave Plasma by Slow Positrons

Abstract

Variable-energy positrons were used as a nondestructive probe for diamond films synthesized on the Si substrate from a gas phase of a CH 4 /H 2 mixture by microwave plasma chemical vapor deposition. The Doppler broadening of the annihilation photons was found to be strongly influenced by the concentration of CH 4 . The values of mean positron diffusion length in the diamond films were found to be decreased by increasing the concentration of CH 4 . The concentration of defects, C , was estimated as follows: 4×10 -4 &lt; C &lt;4×10^-3. A p o s i t r o n i u m ( P s ) f o r m a t i o n i n a v a c a n c y c l u s t e r w a s f o u n d f r o m t h e a n a l y s i s o f t h e D o p p l e r b r o a d e n i n g p r o f i l e s , a n d t h e i n t e n s i t y o f P s w a s f o u n d t o b e a f f e c t e d b y C H _4 a n d / o r H _2 g a s t r a p p e d i n s u c h d e f e c t s . T h e r e s u l t s o f t h e m e a s u r e m e n t s o f R a m a n s p</jats