Heteroepitaxial nucleation of diamond on nickel

• Published in: Diamond and related materials 1998-02, Vol.7 (2), p.276-282
• Main Authors: Sitar, Z., Liu, W., Yang, P.C., Wolden, C.A., Schlesser, R., Prater, J.T.
• Format: Article
• Language: English
• Subjects: Diamond; Heated filament; Heteroepitaxy; Nickel
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(97)00244-6

Highly oriented diamond has been grown on (100) nickel substrates by the hot filament chemical vapor deposition method. Epitaxial nuclei were obtained by a diamond powder seeding and high temperature annealing process. Since the timing of the process was crucial for the achievement of a high degree of orientation and high density of diamond nuclei, a real-time, in-situ laser reflectometry system was developed to monitor changes in surface morphology observed during the high temperature annealing stage. Characteristic features observed in the intensities of reflected and scattered light were interpreted by comparison with scanning electron micrographs of the samples quenched at sequential stages of the process. It was concluded that the scattered light signal can be effectively used as a process steering parameter. Using this technique, oriented nucleation and growth of diamond on Ni was reproducibly achieved. Auger spectroscopy showed that up to 6 at% of carbon was dissolved in the nickel surface layer. The investigation of interfacial microstructures and phases involved by transmission electron microscopy revealed the formation of Ni 4C already in the early stages of nucleation. This phase was manifested as coherent precipitates and is believed to have been the precursor for diamond nucleation. Perfectly epitaxial diamond was grown by this process. The epitaxial relationship was determined by cross-sectional transmission electron microscopy and selected area diffraction analysis.