Diamond (Heteroepitaxial) Nucleation by Ion Beam Impact: A Reality

S. T. Lee, I. Bello, and C. S. Lee

Center of Super-Diamond and Advanced Films (COSDAF) &

Department of Physics and Materials Science

City University of Hong Kong

Hong Kong SAR, China

Abstract

The controlled ion beam method was successfully employed for the first time for the systematic nucleation of diamond over a wide range of experimental conditions. Silicon substrates (held at ~700°C) were bombarded by ~80-200 eV ions from a source fed by a mixture of hydrocarbon/hydrogen/argon gases at a low (10^-4 Torr) pressure. High-resolution TEM analyses confirmed the formation of diamond crystallites in different nucleation sites (on the silicon substrates, adjacent to SiC crystallites, embedded in a non-diamond carbon matrix). Heteroepitaxial diamond crystallites with no misorientation to the silicon substrates were formed on silicon steps. The diamond crystallites existed in the form of both known carbon configurations, i.e., cubic and hexagonal diamond. Most strikingly, among the diamond nuclei we find the first conclusive evidence for the formation of a new diamond polymorph, designated 9R, with a periodicity of 9 layers and a rhombohedral structure. The results greatly improve our current understanding of the diamond nucleation process, open a new, controllable way of growing heteroepitaxial diamond films, and demonstrate the capability of ion beams in nanostructuring carbon materials.

Invited talk: ADC/FCT 2001, August 6-10, 2001, Auburn University Hotel and Conference Center, Auburn, Alabama USA

Corresponding author: S. T. Lee

Center of Super- Diamond and Advanced Films

(COSDAF) and

Department of Physics and Materials Science

City University of Hong Kong

83 Tat Chee Ave,

Kowloon, Hong Kong,

SAR China

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Tel: (852) 2788 9606

e-mail: apannale@cityu.edu.hk