This paper deals with diamond films grown by microwave plasma enhanced chemical vapor deposition technique (MWPECVD) on molybdenum (Mo) substrates of different roughness. The work is motivated by the necessity to overcome the poor adhesion of diamond films on smooth Mo substrates, to be effectively applied as cathodes for aerospace propulsion. The deposition process was monitored in situ by pyrometric interferometry (PI), thus enabling the real-time monitoring of both the rate and the temperature of deposition. The characterization of the obtained diamond films was performed by different techniques such as Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The poor adhesion of diamond films on smooth Mo was solved by roughening the surface substrates, decreasing thermal and intrinsic stresses of the films compared to those depos-ited on smooth ones. In this work, PI technique supported the prediction of the adhesion and the stability of diamond films before their exposure in air, simply by monitoring the deposition temperature. This is a very interesting aspect that has never been addressed in research papers, as pyrometric interferometry is generally used to assess the rate and the temperature of deposition.
Velardi et al. (Tue,) studied this question.