A microstructural and morphological study of diamond crystals and films elaborated by microwave plasma assisted chemical vapour deposition

Abstract

In this work, morphological and microstructural characterization of continuous films and isolated crystals of diamond obtained by microwave plasma-assisted chemical vapour deposition was carried out using transmission electron microscopy and scanning electron microscopy to correlate the diamond morphology and nucleation density with physical parameters of the deposition procedure such as gas composition (argon or oxygen additions to a CH 4 -H 2 system), temperature variations and pretreatment of the silicon substrate. This study was carried out using a particular plasma configuration which allows temperature and plasma density gradients. We point out that good quality diamond film can be achieved by a compromise between a low substrate temperature (obtained by decreasing the microwave power) and good plasma reactivity (obtained by adding gases such as O 2 or argon). In order to obtain a continuous diamond film, it is necessary to scratch the substrate with abrasive particles; we demonstrate that the nucleation density strongly depends on the nature of these particles.