標題: Growth mechanism and properties of the well-aligned-carbon-coated Si nanocones by MPCVD
作者: Chuang, PK
Teng, IJ
Wang, WH
Kuo, CT
材料科學與工程學系
Department of Materials Science and Engineering
關鍵字: Si nanocones (SNCs);carbon nanotubes (CNTs);microwave plasma chemical vapor deposition (MPCVD);growth mechanism
公開日期: 1-十一月-2005
摘要: in order to clarify the possibility to form Si nanocones under the same gas sources (CH4 and H,) and deposition system (microwave plasma chemical vapor deposition (MPCVD)), a process were successfully developed to synthesize the well-aligned amorphous carbon-coated Si nanocones (a:C-SNCs), and their growth mechanism is proposed. This process includes depositing 10 nm Co-catalyst on Si wafer by physical vapor deposition (PVD) and then followed by H-plasma pretreatment to form Co nanoparticles. The pretreated specimens were then used to synthesize various nanostructures under a higher negative Substrate bias. The deposited nanostructures and their compositions were characterized by SEM, HRTEM, ED, EDS and Raman spectroscopy. The results indicate that the most important parameters for forming a:C-SNCs include a lower CH4/H-2 ratio, a higher negative substrate bias and assistance of the carbon-soluble nano-sized catalysts, such as Co. Under a higher enough negative substrate bias (>= 240 V), the etching rates of the catalyst particles and the substrate by the positive species are greater than the carbon deposition rate; a:C-SNCs can be formed. We propose that the cone shape of the nanostructures is essentially resulted from a progressive reduction in catalyst particle sizes under the conditions of higher etching rate than deposition rate on the catalyst surfaces, which may be partially due to a reduction in the Co melting temperature by the presence of carbon in the Co matrix. This mechanism is supported by the facts that a:C-SNCs find no catalysts or very small catalysts on the tips; the catalyst sizes show no significant reduction in sizes after the same a:C-SNCs deposition conditions except no presence of carbon; the diameter of the cone base has no significant differences in size as the original catalyst size after H-plasma pretreatment. Our mechanism gives the guideline to form the nanocone structures by MPCVD with same gas sources (CH4 and H-2). (c) 2005 Published by Elsevier B.V.
URI: http://dx.doi.org/10.1016/j.diamond.2005.06.042
http://hdl.handle.net/11536/13130
ISSN: 0925-9635
DOI: 10.1016/j.diamond.2005.06.042
期刊: DIAMOND AND RELATED MATERIALS
Volume: 14
Issue: 11-12
起始頁: 1911
結束頁: 1915
顯示於類別:會議論文


文件中的檔案:

  1. 000233983600037.pdf