Bias frequency, waveform and duty-cycle effects on the bias-enhanced nucleation of epitaxial diamond

• Published in: Thin solid films 2003-09, Vol.440 (1), p.145-151
• Main Authors: Wolter, S.D., Okuzumi, F., Prater, J.T., Sitar, Z.
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Diamond; Epitaxy; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Plasma processing and deposition
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(03)00827-7

In contrast to conventional DC bias-enhanced nucleation, a pre-carburization step was not needed in the processing of epitaxial diamond on (1 0 0) silicon using pulsed biasing. Otherwise, the procedure showed little frequency dependence on the epitaxial process in the range of 1 Hz–2 kHz, resulting in a constant percentage of highly oriented diamond of nearly 50%. The only variation with frequency was a linear increase in the bias current and a corresponding decrease in the biasing time required to form a quasi-continuous nucleation layer. In contrast, the variation of a 60-Hz square waveform duty cycle from 3 to 75% showed a decreasing hyperbolic relationship with the percentage of oriented diamond, with a plateau of ∼45% occurring at duty cycles of ⩽17%. The bias time to film formation was also determined to be inversely proportional to the duty cycle. The collective data highlights the relevance of the waveform attributes on the epitaxial nucleation of diamond on (1 0 0) silicon.