The structural evolution of nanocrystalline diamond films synthesized by r.f. PECVD

Nanocrystalline diamond films (NDFs) have been deposited using radio-frequency plasma enhanced chemical vapor deposition (r.f.-PECVD) at temperature as low as 500 °C. The CO/H2 ratio has been shown to exert a profound effect on the structure configuration of the NDFs. The nano-scale structures of the films have been shown to evolve from columnar structure to grainy structure with the increase of the CO/H2 ratio from 12:1 to 20:1. Such evolution is suggested to be the result of the enhanced secondary nucleation process. It gives an insight of the nucleation and growth process of NDFs and provides useful information on the optimal control of NDFs deposition.