Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 15: Poster Session

DS 15.36: Poster

Dienstag, 27. März 2007, 15:00–17:00, Poster B

Model Experiments concerning the transition from Nanocrystalline Diamond to Microcrystalline Diamond — •Nicolas Woehrl, Jutta Mack, and Volker Buck — Thin Film Technology Group, Dept. of Physics, University of Duisburg-Essen, Germany

Since over 40 years now diamond films are deposited. Though a lot of work has been done to elucidate the mechanism, the process of diamond deposition - especially the role of surface reactions - is still not fully understood. Because recombination of radicals at the substrate holder - and thus the design of the substrate holder - can influence the properties of the growing film, a mask (3 mm thickness) was introduced on top of the sample for systematical investigation of this effect. Using this experimental setup, a peripheral growth zone was discovered on the silicon substrates where a different form of diamond was growing. By SEM and Raman analysis of the peripheral zone it was found that the deposited film was nanocrystalline there, while it was microcrystalline at the centre. The dependence of the size of this peripheral zone on the substrate from process parameters such as pressure, gasflow and methane fraction in the process gas was investigated. Based on these experiments a model is proposed that explains the results by arguing with the depletion of hydrogen in the gas phase due to recombination effects at the side walls of the substrate holder.