• Title/Summary/Keyword: Si-H bonds

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THIN FILM GROWTH AND SURFACE REACTION ON H-TERMINATED SILICON SURFACE

  • Yasuda, Yukio;Zaima, Shigeaki
    • Journal of Surface Science and Engineering
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    • v.29 no.5
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    • pp.407-414
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    • 1996
  • We have investigated the effects of H atoms on thin film growth processes and surface reactions. In the oxidation of Si, Si surfaces are passivated against the $O_2$ adsorption by terminating dangling bonds with H atoms. Moreover, the existence of Si-H bonds on Si(100) surfaces enhances the structural relaxation of Si-O-Si bonds due to a charge transfer from Si-Si back bonds. In the heteroepitaxial growth of a Si/Ge/Si(100) system, H atoms suppress the segregation of Ge atoms into Si overlayers since the exchange of Ge atoms with Si atoms bound with H must be accompanied with breaking of Si-H bonds. However, 3-dimensional island growth is also promoted by atomic H irradiation, which is considered to result from the suppression of surface migration of adsorbed reaction species and from the lowering of step energies by the H termination of dangling bonds.

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Nanostructural Features of nc-Si : H Thin Films Prepared by PECVD (PECVD 기법에 의해 제조된 nc-Si : H 박막의 나노 구조적 특성)

  • 심재현;정수진;조남희
    • Korean Journal of Crystallography
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    • v.14 no.2
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    • pp.56-61
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    • 2003
  • Nanocrystalline hydrogenated silicon (nc-Si : H) thin films were deposited at room temperature by plasma enhanced chemical vapor deposition (PECVD): a mixture of SiH₄ and H₂ gas was introduced into the evacuated reaction chamber. When the H₂ gas flow rate was low, the density of Si-H₃ bonds was high in the films. On the other hand, when the H₂ gas flow rate was high, e.g., 100 sccm, a large number of Si-H bonds contributed to the passivation of the surface of the large volume of Si nanocrystallites. The relative fraction of the Si-H₃ and Si-H₂ bonds in the amorphous matrix varied sensitively with the H₂ gas flow rate. The variation was associated with the change in the intensity as well as the wavelength of the main PL peaks, indicating the change in the total volume as well as the size of the Si nanocrystallites in the films.

An Analysis of Light-Induced Degradation of PECVD a-Si Films Using $SiF_4$ ($SiF_4$를 이용하여 증착한 PECVD 박막의 빛에 의한 열화도 특성 분석)

  • Jang, K.H.;Choi, H.S.;Han, M.K.
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1019-1021
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    • 1995
  • Light induced degradation of hydrogenated amorphous silicon(a-Si:H) are related to the number of weak dangling bonds which are thought to be responsible for the Staebler-Wronski effects, and caused the many photoelectric problems in applications of thin film transistors and solar cell, etc. In this paper, we deposited fluorinated amorphous silicon films(a-Si:H;F) with $SiH_4$ and $SiF_4$ gas mixture and investigated the effects of fluorine atoms on the evoluations of the crystallinity and improvements of light instability. We have found that micro-crystallinity produced in a-SI:H;F films and marked maximum value of 22% at the flow rate of $SiH_4:SiF_4$=2:10 sccm by UV spectrophotometer measurement, while n-Si:H film deposited with only $SiH_4$ gas showed no crystallinity. Light-induced degradation property of a-Si:H;F films is also improved which is mainly due to the etching effects of fluorine atoms on the weak Si-Si bonds and unstable hydrogen bonds. It is considered that involving fluorine atoms in a-Si:H films may contribute to the suppression of light-induced degradation and evolution of micro-crystallinity.

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A study on the formation and properties of TMDSO/$O_2$ thin film by the RF Plasma CVD (RF Plasma CVD에 의한 TMDSO/$O_2$의 합성과 박막의 특성에 관한 연구)

  • Kim, I.S.;Kim, G.Y.;Kang, D.P.;Yun, M.S.;Park, S.H.
    • Proceedings of the KIEE Conference
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    • 1991.11a
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    • pp.265-268
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    • 1991
  • In the study, PPTMDSO(plasma-polymerized tetramethyldisiloxane) films were deposited on on glass substrate in a paralled plate reactor. As the function of RF power increased from 20 W to 110 W, and the substrate temperature increased from $25^{\circ}C$ to $100^{\circ}C$, the deposit ion rate, increased. When oxygen was intentionally added in monomer vapor, the concentration of Si-O-Si bonds increased while C-H, Si-H, -CH3, Si(CH3)x, -CH3, and Si-C bonds decreased in IR spectra. Thermal stability of PPTMSDO film were investigated and weight loss at $800^{\circ}C$ was 7.3 %.

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Effects of Deposition Parameters on the Bonding Structure and Optical Properties of rf Sputtered a-Si$_{1-x}$C$_{x}$: H films (RF 스퍼터링으로 증착된 a-Si$_{1-x}$C$_{x}$: H 박막의 결합구조와 광학적 성질에 미치는 증착변수의 영향)

  • 한승전;권혁상;이혁모
    • Journal of Surface Science and Engineering
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    • v.25 no.5
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    • pp.271-281
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    • 1992
  • Amorphous hydrogenated silicon carbide(a-Si1-xCx : H) films have been prepared by the rf sputtering using a silicon target in a gas mixture of Argon and methane with varying methane gas flow rate(fCH) in the range of 1.5 to 3.5 sccm at constant Argon flow rate of 30sccm and rf power in the range of 3 to 6 W/$\textrm{cm}^2$. The effects of methane flow rate and rf power on the structure and optical properties of a-Si1-xCx : H films have been analysed by measuring both the IR absorption spectrum and the UV transmittance for the films. With increasing the methane flow rate, the optical band gap(Eg) of a-Si1-xCx : H films increases gradually from 1.6eV to the maximum value of 2.42eV at rf power of 4 W/$\textrm{cm}^2$, which is due to an increases in C/Si ratio in the films by an significant increase in the number of C-Hn bonds. As the rf power increases, the number of Si-C and Si-Hn bonds increases rapidly with simultaneous reduction in the number of C-Hn bonds, which is associated with an increase in both degree of methane decomposition and sputtering of silicon. The effects of rf power on the Eg of films are considerably influenced by the methane flow rate. At low methane flow rate, the Eg of films decreased from 2.3eV to 1.8eV with the rf power. On the other hand, at high methane flow rate, that of films increased slowly to 2.4eV.

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In-situ Fluorine Passivation by Excimer Laser Annealing

  • Jung, Sang-Hoon;Kim, Cheon-Hong;Jeon, Jae-Hong;Yoo, Juhn-Suk;Han, Min-Koo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.155-156
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    • 2000
  • We propose a new in-situ fluorine passivation of poly-Si TFTs by excimer laser annealing to reduce the trap density and improve the reliability significantly. This improvement is due to the formation of stronger Si-F bonds than Si-H bonds which passivate the trap states.

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Adsorption Stnlctures of Benzene and Pyridine on a $Si(5\;5\;12)-2{\times}1$ ($Si(5\;5\;12)-2{\times}1$ 표면에 벤젠과 피리딘의 결함구조)

  • Jang S. H.;Oh S.;Hahn J. R.;Jeong H.;Jeong S.
    • Journal of the Korean Vacuum Society
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    • v.15 no.1
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    • pp.50-56
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    • 2006
  • We investigated the adsorption of benzene and pyridine on $Si(5\;5\;12)-2\times1$ at 80 K by using variable-low temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The benzene molecule most strongly binds to two adatoms on the D3 and D2 units in a tilted butterfly configuration, which consists of $di-\sigma$ bonds between C atoms and Si adatoms and two C=C double bonds in the benzene molecule Pyridine molecules interact with adatom(s) on the D2 and D3 units through both Si-N dative bonding and $di-\sigma$ bonds. The dative bonding through the lone pair electrons of N atom produces a vertical configuration (pyridine-like), which is more stable than $di-\sigma$ bonds $Di-\sigma$ bonds can be formed either through Si-N1 and Si-C4 or Si-C2 and Si-C5.

Solid-State $^1H$ and $^{29}Si$ NMR Studies of Silicate and Borosilicate Gel to Glass Conversion

  • 양경화;우애자
    • Bulletin of the Korean Chemical Society
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    • v.17 no.8
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    • pp.696-699
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    • 1996
  • Silicate and borosilicate gels were prepared by the sol-gel process and thermally treated in the 150-850 ℃ temperature range. Solid-state 1H MAS and 29Si CP/MAS NMR spectroscopy were used to investigate the effects of heat treatments on the silicate gel to glass conversion process. The 1H NMR isotropic chemical shifts and the relative intensities of hydrogen bonded and isolated silanol groups have been used to access the information concerning the dehydration process on the silicate gel surface. The 29Si NMR isotropic chemical shifts affected by the local silicon environment have been used to determine the degree of crosslinking, i.e. the number of siloxane bonds. These NMR results suggest that the silicate gel to glass conversion process is occurred by two stages which are dependent on the temperature; (1) the formation of particles up to 450 ℃ and (2) the formation of large particles by aggregation of each separated single particle above 450 ℃. In addition, the effects of B atom on the formation of borosiloxane bonds in borosilicates have been discussed.

INFRARED ABSORPTION MEASUREMENT DURING LOW-TEMPERATURE PECVD OF SILICON-OXIDE FILMS

  • Inoue, Yasushi;Sugimura, Hiroyuki;Takai, Osamu
    • Journal of Surface Science and Engineering
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    • v.32 no.3
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    • pp.297-302
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    • 1999
  • In situ measurement of infrared absorption spectra has been performed during low-temperature plasma-enhanced chemical vapor depositiion of silicon-oxide films using tetramethoxysilane as a silicon source. Several absorption bands due to the reactant molecules are clearly observed before deposition. In the plasma, these bands completely disappear at any oxygen mixing ratio. This result shows that most of the tetramethoxysilane molecules are dissociated in the rf plasma, even C-H bonds. Existence of Si-H bonds in vapor phase and/or on the film surface during deposition has been found by infrared diagnostics. We observed both a decrease in Si-OH absorption and an increase in Si-O-Si after plasma off, which means the dehydration condensation reaction continues after deposition. The rate of this reaction is much slower than the deposition ratio of the films.

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In-Situ Fluorine Passivation by Excimer Laser Annealing

  • Jung, Sang-Hoon;Kim, Cheon-Hong;Jeon, Jae-Hong;Yoo, Juhn-Suk;Han, Min-Koo
    • Journal of Information Display
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    • v.1 no.1
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    • pp.25-28
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    • 2000
  • We propose a new in-situ fluorine passivation of poly-Si TFTs using excimer laser annealing to reduce the trap state density and improve reliability significantly. To investigate the effect of an in-situ fluorine passivation, we have fabricated fluorine-passivated p-channel poly-Si TFTs and examined their electrical characteristics and stability. A new in-situ fluorine passivation brought about an improvement in electrical characteristic. Such improvement is due to the formation of stronger Si-F bonds than Si-H bonds in poly-Si channel and $SiO_2$/Poly-Si interface.

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