Browsing by Author "Li, YW"

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Effect of post-treatment on electrical properties of amorphous hydrogenated carbon films deposited by gridless ion beam deposition
(2003-01-01)
Chen, CF
;
Li, YW
;
Huang, HL
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Amorphous hydrogenated carbon (a-C:H) films were deposited from the gas mixtures of acetylene (C2H2) and argon (Ar) in a gridless ion beam deposition (GIBD) system fed with dc power. Vacuum annealing and hydrogen plasma treatment were performed on the a-C:H films and their effects on the physical and electrical properties of the films were investigated. Film structure and properties were investigated as a function of the C2H2 flow rate by Raman spectroscopy. Through the Raman spectra, we found that the Raman I-D/I-G intensity ratio increases as annealing temperature increases, which indicates a more graphite-like character in the annealed films. The dielectric constant of the annealed a-CA films was reduced from 3.8 to 2.9 and the thickness also slightly decreased with increasing annealing temperature. However, the leakage current density and dielectric constant of the hydrogen-plasma-treated a-C:H films were clearly lower than the as-deposited a-C:H films.
Effects of ammonia plasma treatment on the electrical properties of plasma-enhanced chemical vapor deposition amorphous hydrogenated silicon carbide films
(2002-09-01)
Li, YW
;
Chen, CF
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Amorphous hydrogenated silicon carbide (a-SiC:H) films were deposited from a mixture of silane and methane gases using the plasma-enhanced chemical vapor deposition (PECVD) process. The properties of the film. following ammonia plasma treatment, are reported. A lower silane flow rate reduces the refractive index, but increases the carbon content and the optical band gap. Increasing the carbon concentration of the a-SiC:H films reduces the dielectric constant. The films were treated with ammonia plasma for various treatment periods. The original Film has a smooth surface with a roughness of 0.231 nm but increasing the ammonia plasma treatment period gradually roughens the surface. The chemical bonding nature of the a-SIC:H films with higher silicon content was investigated by X-ray photoelectron spectro.scop, Various nitrogen ioni/ation species reacted with Si to promote the formation of silicon nitride. As a result, although the dielectric constant of the a-SiC:H films, increased slightly, the leakage current density declined as the ammonia plasma treatment time increased.
Electrical properties of diamond-like carbon films deposited using a filtered cathodic arc system
(2001-02-01)
Li, YW
;
Chen, CF
;
Tseng, YJ
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材料科學與工程學系
;
Department of Materials Science and Engineering
A new filter are deposition (FAD) system has been developed to satisfy the requirements of magnetic storage devices;. This work briefly describes the 45 degrees magnetic filter cathodic are deposition process and investigates how substrate bias, hydrogenating, and nitrogen-doping affect the electrical properties of amorphous diamond-like carbon films. Experimental results indicate that increasing in substrate bias and/or nitrogen doping into the film during the process would lower the resistance of the film. All these evidences indicate the pout-deposited film is more "graphite-like". The effect of hydrogen flow in the film is less significant. It is believed that the hydrogen can prevent the nucleation of the graphite phase, and can also stabilize of sp(3) bonding. The phenomenon clearly indicates that the film is more "diamond-like".
Substrate bias effect on amorphous hydrogenated carbon films deposited by filtered cathodic arc deposition
(2001-11-01)
Li, YW
;
Chen, CF
;
Shue, YB
;
Yu, TC
;
Chang, JJK
In the present study, we briefly describe the 45 degrees angle magnetic filtered arc deposition (FAD) process and investigate the effect of substrate bias on the hardness of amorphous carbon (a-C) films. An attempt is made to correlate the microstructure. chemical composition and chemical bonding states with the hardness of the corresponding films. After deposition. the film properties v,ere analyzed by Raman spectroscopy and nanoindentation system (NIS). It was found that amorphous carbon films possess highest hardness when deposited at substrate biases ranging from -50 V to -100 V. The hardness values do not show good correlation with Raman I(D)/I(G) ratio. Hydrogen additions to the system help prevent the nucleation of the graphite phase, and stabilize the sp(3) bonding of amorphous hydrogenated carbon films. Hydrogen affected on the small graphitic crystalline growth. Films have higher hardness when they have higher fraction of sp(3) content.
Substrate bias effect on amorphous nitrogenated carbon films deposited by filtered arc deposition
(2002-03-01)
Li, YW
;
Shue, YB
;
Chen, CF
;
Yu, TC
;
Chang, JJK
The effect of substrate bias and nitrogen incorporation on the structure and hardness properties of amorphous carbon (a-C) films is characterized in terms of its composition, sp(3) bonding fraction, and Raman spectra. The films' properties were analyzed using Raman spectroscopy, Auger electron spectroscopy (AES), and nanoindentation system (NIS). Experimental results indicate that a-C films were found to possess the highest hardness when deposited at a substrate bias ranging from -50 to -100 V. In addition, the hardness values do not correlate well with the Raman I(D)/I(G) ratio. The hardness of films increases with their sp(3) bonds fraction. Furthermore, nitrogen content increases with increasing substrate bias on amorphous nitrogenated carbon (a-C:N) films, and influences the growth of small graphitic crystallines. (C) 2002 Elsevier Science B.V. All rights reserved.
The effects of hydrogen plasma treatment on the plasma-enhanced chemical vapor deposition a-SiC : H films
(2004-08-01)
Chen, CF
;
Li, YW
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Amorphous hydrogenated silicon carbide (a-SiC:H) films were deposited using plasma-enhanced chemical vapor deposition (PECVD) process. Reducing silane flow rate increased the carbon concentration and optical band gap in the a-SiC:H films, but decreased the refractive index and dielectric constant. X-ray photoelectron spectroscopy (XPS) data revealed that the carbon concentration decreased as the methane flow rate increased, but the silicon concentration increased. Increasing the carbon concentration in the a-SiC:H film reduces the dielectric constant of the film. The carbon-rich a-Si0.24C0.68:H,, films treated with hydrogen plasma for various periods, were converted into films with more silicon content. Increasing the hydrogen plasma treatment period gradually roughened the surface even though the original film had a smooth surface, with a roughness <0.231 nm. The leakage current density of the hydrogen plasma treated a-Si0.24C0.68:1-1, films declined as the duration of the hydrogen plasma treatment period decreased.