The origin of preferred orientation during carbon film growth

• Published in: Journal of physics. Condensed matter Vol. 21; no. 22; pp. 225003 - 225003 (9)
• Main Authors: Taylor, M B, Lau, D W M, Partridge, J G, McCulloch, D G, Marks, N A, Teo, E H T, McKenzie, D R
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 03.06.2009; Institute of Physics
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Vapor phase epitaxy; growth from vapor phase; Annealing; Channeling; Transmission electron microscopy; Filtered cathodic vacuum arc; Molecular dynamics method; Physical vapor deposition; Modelling; Microstructure; Preferred orientation
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/21/22/225003

Carbon films were prepared using a filtered cathodic vacuum arc deposition system operated with a substrate bias varying linearly with time during growth. Ion energies were in the range between 95 and 620 eV. Alternating dark, high density (sp(3) rich) bands and light, low density (sp(2) rich) bands were observed using cross-sectional transmission electron microscopy, corresponding to abrupt transitions between materials with densities of approximately 3.1 and 2.6 g cm(-3). No intermediate densities were observed in the samples. The low density bands show strong preferred orientation with graphitic sheets aligned normal to the film. After annealing, the low density bands became more oriented and the thinner high density layers were converted to low density material. In molecular dynamics modelling of film growth, temperature activated structural rearrangements occurring over long timescales ([Formula: see text] ps) caused the transition from sp(3) rich to oriented sp(2) rich structure. Once this oriented growth was initiated, the sputtering yield decreased and channelling was observed. However, we conclude that sputtering and channelling events, while they occur, are not the cause of the transition to the oriented structure.