Interfacial oxide and carbide phases in the deposition of diamond films on beryllium metal

• Published in: Diamond and related materials 2000-07, Vol.9 (7), p.1327-1330
• Main Authors: Catledge, Shane A, Vohra, Yogesh K
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; CVD; Diamond; Diffusion; interface formation; Exact sciences and technology; Interface/interfacial; Materials science; Metal; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Solid surfaces and solid-solid interfaces; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(00)00246-6

We have investigated beryllium metal as a substrate for the microwave plasma chemical vapor deposition of diamond films. The dependence of oxide and carbide interfacial phase formation with temperature and their influence on diamond nucleation and growth behavior were studied by thin film X-ray diffraction. Although a native oxide (BeO with the hexagonal wurtzite structure) remains for the range of substrate temperatures studied (700–800°C), the formation of a carbide (Be 2C with the cubic antifluorite structure) is found only above a critical substrate temperature of approximately 750°C. Without the formation of Be 2C, the diamond growth rate is low and a significant amorphous carbon component is observed. Just above the critical temperature, films exhibited high growth rates with high phase-purity diamond. Thick films (>30 μm) grown above the critical temperature were observed to fracture completely within the Be 2C layer, suggesting this to be the weak structural link.