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Enhanced spontaneous nucleation of diamond nuclei in hot and cold microwave plasma systems
Author(s) -
Izak Tibor,
Sveshnikov Alexey,
Demo Pavel,
Kromka Alexander
Publication year - 2013
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201300117
Subject(s) - nucleation , diamond , plasma , microwave , hydrogen , chemistry , materials science , metallurgy , organic chemistry , physics , quantum mechanics
In this work, the diamond nucleation is studied using two different deposition systems: (i) focused microwave plasma (labeled as “hot plasma”) and (ii) pulsed‐linear antenna microwave plasma (“cold plasma”). For the hot plasma, the influence of CH 4 concentration in the hydrogen rich gas mixture on the self nucleation is investigated. It is found that higher CH 4 concentration leads to increased diamond nucleation density, but also the amount of sp 2 carbon bonds increases within the deposits. In the cold plasma, we investigate the influence of CO 2 addition into CH 4 /H 2 and total process pressure. Experimental results reveal a strong dependence of CO 2 and pressure on spontaneous nucleation. The nucleation density ( N d ) typical for non‐treated substrates (∼10 5 cm −2 ) is improved by four orders to 10 9 cm −2 in cold plasma thanks to increased CH 4 and CO 2 concentrations. The highest nucleation density in the hot plasma system is still one order lower (∼4 × 10 7 cm −2 ). Moreover, in cold plasma a bimodal distribution function of diamond clusters is observed for low ratios of CO 2 /H 2 . Observed differences in N d values are attributed to plasma properties and surface chemistry. Based on the experimental results, possible mechanisms contributing to the spontaneous nucleation process are discussed.