Browsing by Author "Yan, JK"

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Chemical vapor deposition of uniform and high-quality diamond films by bias-enhanced nucleation method
(2006-03-01)
Yan, JK
;
Chang, L
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Diamond films on 1 x 1 cm(2) Si (100) substrates were synthesized by microwave plasma chemical vapor deposition (MWCVD) using mixture of methane and hydrogen gases. Bias-enhanced nucleation method was used to avoid any mechanical pretreatments. Distribution of deposited diamond crystallites in terms of density, size, and morphology has been significantly improved over all the Si substrate surface area by using a novel designed Mo anode. Films were characterized from the center to the edges of substrates using scanning electron microscopy, transmission electron microscope, and Raman analysis. The results also show that uniform diamond films can be obtained by short bias nucleation period using a dome-shaped Mo anode. The diamond crystallites were directly deposited on Si substrate. Using 2% CH4 in the growth stage, high quality diamond films in the < 100 > texture can be obtained with relatively smooth surface. (c) 2005 Elsevier B.V. All rights reserved.
Diamond deposition on Au/amorphotis Si thin films
(2004-04-01)
Kao, CK
;
Yan, JK
;
Chang, L
;
Cho, SY
;
Chen, HG
Au/amorphous Si/SiO2/Si structure was used as substrate for diamond deposition by microwave plasma CVD. The Au-Si phase diagram shows a eutectic point at 363 degreesC. At deposition temperatures of 700-800 degreesC, the Au and amorphous Si films were alloyed as liquid during deposition, which resulted in formation of an array of single crystalline Si whiskers. Microstructural characterization shows that the Si whiskers have a diameter in the range of 50 nm-5 mum with facet on the top surface. The Si whiskers are shown to be oriented along <311> directions. Diamond particles deposited are found only on top of the Si whiskers. The diamond particles can be either of polycrystalline or single crystalline characteristics. (C) 2004 Elsevier B.V. All rights reserved.
Growth and characterization of chemical-vapor-deposited zinc oxide nanorods
(2006-03-01)
Wu, CL
;
Chang, L
;
Chen, HG
;
Lin, CW
;
Chang, TF
ZnO nanorods were grown on Si substrates by metal-organic chemical vapor deposition (CVD). The ZnO nanorods were characterized by scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction. It was found that highly oriented ZnO single-crystalline nanorods were formed only on the substrate coated with a gold film. Without the gold, ZnO was deposited as a continuous film. No Au was observed on top of the ZnO nanorods, implying that the Au plays no role as catalytic metal in vapor-liquid-solid mechanism for formation of ZnO nanorods. In CVD, oriented ZnO nanorods along the c-axis were grown as a result of < 111 > textured Au. High-resolution TEM shows that the gold layer and ZnO are in orientation relationship of Au 111 planes//ZnO (0002) basal planes. (c) 2005 Elsevier B.V. All rights reserved.
Microwave plasma chemical vapor deposition of cone-like structure of diamond/SiC/Si on Si (100)
(2005-11-01)
Yan, JK
;
Chang, L
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Diamond deposition on I x I cm 2 Si (100) substrates with bias was carried out by microwave plasma chemical vapor deposition (MPCVD). Distribution of deposited diamonds has been significantly improved in uniformity over all the Si substrate surface area by using a novel designed dome-shaped Mo anode. The deposits were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman analysis. SEM observations show that there is a high density of cone-like particles uniformly deposited on the surface of the substrate in short bias nucleation period. The average diameter, height and density of cone-like structure were increased with methane concentration in the bias stage. TEM reveals that the cone-like structure is actually composed of Si conic crystal covered with diamond. Between Si and diamond, a thin layer of cubic SiC is found in epitaxy with Si. Furthermore, for 3% CH4 concentration, the range of diameter of cone-like structure was about 2090 nm and the size of diamond was about 10-60 nm. (c) 2005 Elsevier B.V. All rights reserved.
The orientation effect of silicon grains on diamond deposition
(2005-11-01)
Su, YH
;
Chang, L
;
Chen, HG
;
Yan, JK
;
Chou, T
Diamond deposition on mirror-polished polycrystalline silicon substrates which have grains in various orientations has been investigated using electron backscatter diffraction (EBSD) method with scanning electron microscopy (SEMI). Diamond was deposited by microwave plasma chemical vapor deposition with application of a negative bias voltage oil the substrate. The evidence from systematic SEM observations shows that silicon orientation determined by EBSD has a strong effect on diamond nucleation. In general, the diamond nucleation density on Si grains oriented close to < 100 > is the highest, while it is the lowest for those grains close to < 111 >, under the same experimental conditions for deposition. The same phenomena have been observed in the range of methane concentration from 2% to 4% in hydrogen. (c) 2005 Elsevier B.V. All rights reserved.