Influence of substrate temperature on formation of ultrananocrystalline diamond films deposited by HFCVD argon-rich gas mixture

• Published in: Diamond and related materials 2009-10, Vol.18 (10), p.1283-1288
• Main Authors: Barbosa, D.C., Almeida, F.A., Silva, R.F., Ferreira, N.G., Trava-Airoldi, V.J., Corat, E.J.
• Format: Article
• Language: English
• Subjects: Activation energy; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Diamond; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Growth kinetics; HFCVD; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; sp 2 growth; Specific materials; Surface and interface electron states; Surface states, band structure, electron density of states; Theory and models of film growth
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2009.05.002

The influence of the substrate temperature on the formation of ultrananocrystalline diamond (UNCD) thin films, prepared by an argon-based hot filament chemical vapor deposition (HFCVD), is discussed in this work. The gas mixture used for diamond growth was 1 vol.% methane, 9 vol.% hydrogen and 90 vol.% argon at a total flow rate of 200 sccm and at a total pressure of 30 Torr. The substrate temperature range was from 550 to 850 °C at deposition time of 8 h. Mass growth rate was determined at different deposition temperatures. The activation energy for UNCD growth, determined from the Arrhenius plot, was lower (5.7 kcal/mol) than the values found for standard diamond deposition (around 11 kcal/mol). In this work, we suggest that the activation energy was lower because the growth of these films occurs at conditions that there is a high growth competition between diamond phase and sp 2 phases. To support this hypothesis, systematic characterization studies based on Raman scattering spectroscopy, high-resolution X-ray diffractometry and high-resolution scanning electron microscopy were performed.