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RISS 인기검색어
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- 저자 : Eungahn Lee (검색결과 3 건)
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Sangsoo Noh,Eungahn Lee,Xiaoan Fu,Chen Li,Mehran Mehregany 한국전기전자재료학회 2005 Transactions on Electrical and Electronic Material Vol.6 No.6
The physical and electrical properties of polycrystalline β-SiC were studied according to different nitrogen doping concentration. Nitrogen-doped SiC films were deposited by LPCVD(low pressure chemical vapor deposition) at 900 ºC and 2 torr using 100 % H2SiCl2 (35 sccm) and 5 % C2H2 in H2(180 sccm) as the Si and C precursors, and 1 % NH3 in H2(20~100 sccm) as the dopant source gas. The resistivity of SiC films decreased from 1.466 Ω×㎝ with NH3 of 20 sccm to 0.0358 Ω×㎝ with 100 sccm. The surface roughness and crystalline structure of β-SiC did not depend upon the dopant concentration. The average surface roughness for each sample 19-21 ㎚ and the average surface grain size is 165 ㎚. The peaks of SiC(111), SiC(220), SiC(311) and SiC(222) appeared in polycrystalline β-SiC films deposited on Si/SiO2 substrate in XRD(X-ray diffraction) analysis. Resistance of nitrogen-doped SiC films decreased with increasing temperature. The variation of resistance ratio is much bigger in low doping, but the linearity of temperature dependent resistance variation is better in high doping. In case of SiC films deposited with 20 sccm and 100 sccm of 1 % NH3, the average of TCR(temperature coefficient of resistance) is -3456.1 ppm/°C and -1171.5 ppm/°C, respectively.
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A Study of Properties of 3C-SiC Films deposited by LPCVDwith Different Films Thickness
Sangsoo Noh,Jeonghwan Seo,Eungahn Lee 한국전기전자재료학회 2008 Transactions on Electrical and Electronic Material Vol.9 No.3
The electrical properties and microstructure of nitrogen-doped poly 3C-SiC films were studied according to different thickness. Poly 3C-SiC films were deposited by LPCVD(low pressure chemical vapor deposition) at 900 ˚C and 4 Torr using SiH₂Cl₂ (100 %, 35 sccm) and C₂H₂ (5 % in H₂, 180 sccm) as the Si and C precursors, and NH₃ (5 % in H₂, 64 sccm) as the dopant source gas. The resistivity of the 3C-SiC films with 1,530 A of thickness was 32.7 Ω-cm and decreased to 0.0129 Ω-cm at 16,963 A In XRD spectra, 3C-SiC is so highly oriented along the (1 1 1) plane at 2 θ = 35.7 ˚ that other peaks corresponding to SiC orientations are not presented. The measurement of resistance variations according to different thickness were carried out in the 25 ˚C to 350 ˚C temperature range. While the size of resistance variation decreases with increasing the films thickness, the linearity of resistance variation improved.
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Sangsoo Noh,Wen-Teng Jang,Eungahn Lee,Sungil Lee 한국전기전자재료학회 2007 Transactions on Electrical and Electronic Material Vol.8 No.4
In this work, Ni thin films with different thickness from 1,523 Å to 9,827 Å were deposited for the application of micro thermal flow sensors by a magnetron sputtering and oxidized through annealing at 450 ℃ with increasing annealing time. The initial variation of resistivity decreased radically with increasing films thickness, then gradually stabilizes as the thickness increases. The resistivity of Ni thin films with 3,075 Å increased suddenly with increasing annealing time at 450 ℃, then gradually stabilizes as the thickness increases after the annealing time 9h. In case of 3,075 Å and 9,827 Å films, the average of TCR values, measured for the operating temperature range of 0℃ to 180℃, were 2,413.1 ppm/℃ and 4,438.5 ppm/℃, respectively. Because of their high resistivity and very linear TCR, Ni oxide thin films are superior to pure Ni and Pt thin films for flow and temperature sensor applications.
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