DIRAC-DELTA NUCLEATION IN THE FRAMEWORK OF AVRAMIS MODEL - THE CASE OF DIAMOND GROWTH ON DEFORMED SI(100)

The nucleation and growth kinetics of diamond deposited by hot-filamen t chemical vapour deposition (HFCVD) on Si(100) substrates, previously deformed by uniaxial compression dong the [100] direction, have been investigated Although the nucleation density at saturation (0.04-0.06 mu m(-2)) was similar to those measured on virgin, as-received Si(100) wafers, the kinetics of stable nucleus formation resembled the fast k inetics observed for substrates which were mechanically abraded prior to CVD in order to enhance diamond nucleation. The results definitely indicate that diamond nucleation occurs randomly with a rate that is a Dirac delta function. The time dependence of the substrate fraction w hich is covered by islands was measured, and a good agreement with Avr ami's kinetics for 2D phase transitions was found. The total island pe rimeter has also been measured as a function of the covered surface, a nd is well described by the analytical model recently developed [M. To mellini and M. Fanfoni, Surf Sci. 349 (1996) L191]. The observed fast nucleation has been attributed to stress-induced defects pre-existing at the surface and which provides suitable sites for diamond growth. ( C) 1997 Elsevier Science B.V.