Nitrogen stabilized 〈100〉 texture in chemical vapor deposited diamond films

Abstract

We have studied the influence of nitrogen impurities in CH4/H2 gas mixtures on the structure and morphology of polycrystalline diamond films prepared by microwave plasma assisted chemical vapor deposition. The nitrogen concentration in the process gas was varied between 1 and 1000 ppm. Optical emission spectroscopy was applied to detect the nitrogen in the plasma via emission from CN radicals. The morphology and texture of polycrystalline films prepared with various N2 impurity levels and CH4 concentrations in the range 0.5%–2% was investigated using scanning electron microscopy and x-ray texture analysis. For the films prepared with low methane concentrations (e.g., 0.5%) only a minor influence of the nitrogen was observed. However, most interestingly, for higher methane concentrations (1%–2%) the addition of small amounts of nitrogen turned out to have a tremendously beneficial effect on the film morphology and structure. Films prepared without additional nitrogen are of nanocrystalline structure and of minor quality, whereas films prepared with nitrogen concentrations in the range 10–100 ppm exhibit a pronounced 〈100〉 texture and a considerably improved crystalline quality as judged by Raman spectroscopy.

Characterization of a-C:H:N deposition from CH4/N2 rf plasmas using optical emission spectroscopy

“…The CN violet system has three strong sequences with heads at 421.6, 388.3, and 359 nm ͑the 388.3 head being the strongest͒ 28 which have been observed by other workers. [37][38][39] In our system, the 359 nm band is obscured by the strong N 2 second positive bands but when the 388.3 nm band is well developed, bands associated with the 421.6 nm sequence appear.…”

A mechanism for crystal twinning in the growth of diamond by chemical vapour deposition

“…Nitrogen in the growth environment is observed to enhance step bunching on the growing surface (de Theije et al 2000). Additionally, nitrogen added to the growth environment influences the morphology of the diamond crystals and the crystalline texture of the polycrystalline growth (Locher et al 1994;Cao et al 1996;Yan & Vohra 1999).…”

Effect of N and B doping on the growth of CVD diamond(100):H(2×1)surfaces

“…[3][4][5] Interest in the role of N in CVD diamond has been heightened by experimental observations that N preferentially catalyses growth in the ͑100͒ direction. [6][7][8] To the authors' knowledge, no serious attempts have been made to explain these phenomena theoretically. Indeed, it is unclear whether these somewhat puzzling results are compatible with the Harris-Goodwin mechanism or if in doping cases a different growth process is at work.…”