Browsing by Author "Yan, Jhih-Kun"

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Bias-enhanced nucleation of oriented diamonds on cone-like Si
(2008-04-01)
Chang, Li
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Yan, Jhih-Kun
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材料科學與工程學系
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Department of Materials Science and Engineering
Uniform distribution of bias-enhanced nucleation of diamond has been improved on Si substrate of an area of 1 x 1 cm(2) by using a domeshaped Mo counter electrode in a microwave plasma chemical vapor deposition reactor. A nucleation density of 10(9) cm(2) can be reached within a few minutes when the bias voltage of - 100 V is applied on the substrates. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that a single-crystalline diamond in a few nanometered size can be deposited on a volcano-shaped cubic SiC which is epitaxially formed on a Si cone. Examination reveals a large fraction of diamond nuclei are oriented along with one side of SiC on each Si cone. The Si cone formed on the Si substrate is due to plasma etching. The diamond nuclei have a shape close to rhombus in TEM. With further growth, secondary nucleation of diamond occurs on top of diamond nuclei and SiC which grows with Si cones. As a result, polycrystalline diamonds are deposited on each Si cone. (C) 2008 Elsevier B.V. All fights reserved.
Chemical vapour deposition of oriented diamond nanocrystallites by a bias-enhanced nucleation method
(2006-11-28)
Yan, Jhih-Kun
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Chang, Li
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材料科學與工程學系
;
Department of Materials Science and Engineering
A microwave plasma chemical vapour deposition (MPCVD) system has been used to deposit nanometre-sized single-crystalline diamonds on 1 x 1 cm(2) Si(100) substrates. The distribution of deposited diamonds has good uniformity over the whole Si substrate surface by using a dome-shaped Mo anode which allows the application of bias-enhanced nucleation. The morphology and crystallinity of the deposits on Si were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with electron diffraction and lattice images. SEM and TEM observations show that oriented diamond nuclei as single crystals with facets can form on self-formed Si cones through epitaxial SiC within a short bias period. After a longer bias time, it has been observed that polycrystalline diamonds formed as a result of secondary nucleation.
Growth of diamond nanoplatelets by CVD
(2008-07-01)
Chen, Hou-Guang
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Chang, Li
;
Cho, Shih-Yin
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Yan, Jhih-Kun
;
Lu, Chun-An
Hexagonal, single-crystalline, diamond nanoplatelets synthesized by microwave plasma (MP)CVD on Au-Ge alloy and nanocrystalline diamond (nc-diamond) film substrates, respectively, are reported. On the nc-diamond matrix, hexagonal diamond nanoplatelets can grow to a thickness of as little as approximately 10 nm. The effects of various processing parameters, such as methane concentration, microwave power, and gas pressure, on the growth of diamond nanoplatelets are explored. High-resolution transmission electron microscopy (HRTEM) reveals that the diamond nanoplatelets contain multi-parallel twins, and the side faces of the platelets exhibit {100}/{111} ridge-and-trough structure. Anisotropic growth of diamond nanoplatelet is believed to result from the side face structure of the twinned platelets and intensive plasma reaction.