Intrinsic and Doped m c-Si:H TFT Layers using 13.56 MHz PECVD at 250°C

2004 ◽  
Vol 808 ◽  
Author(s):  
Czang-Ho Lee ◽  
Denis Striakhilev ◽  
Arokia Nathan
Keyword(s):  
Performance Improvement ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Rf Power ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Bias Stress ◽  
Hydrogen Dilution ◽  
Low Threshold

ABSTRACTUndoped and n+ hydrogenated microcrystalline silicon (μc-Si:H) films for thin film transistors (TFTs) were deposited at a temperature of 250°C with 99 ∼ 99.6 % hydrogen dilution of silane by standard 13.56 MHz plasma enhanced chemical vapor deposition (PECVD). High crystallinity m c-Si:H films were achieved at 99.6 % hydrogen dilution and at low rf power. An undoped 80 nm thick m c-Si:H film showed a dark conductivity of the order of 10−7 S/cm, the photosensitivity of an order of 102, and a crystalline volume fraction of 80 %. However, a 60 nm thick n+ μc-Si:H film deposited using a seed layer showed a high dark conductivity of 35 S/cm and a crystalline volume fraction of 60 %. Using n+ μc-Si:H films as drain and source contact layers in a-Si:H TFTs provides substantial performance improvement over n+ a-Si:H contacts. Finally, fully μ c-Si:H TFTs incorporating intrinsic m c-Si:H films as channel layers and n+ μc-Si:H films as contact layers have been fabricated and characterized. These TFTs exhibit a low threshold voltage and a field effect mobility of 0.85 cm2/Vs, and are far more stable under gate bias stress than a-Si:H TFTs.

Transport Path in Hydrogenated Microcrystalline Silicon

2002 ◽  
Vol 715 ◽  
Author(s):  
N. Wyrsch ◽  
C. Droz ◽  
L. Feitknecht ◽  
J. Spitznagel ◽  
A. Shah
Keyword(s):  
Raman Spectroscopy ◽  
Volume Fraction ◽  
Conductivity Measurement ◽  
Dark Conductivity ◽  
Transition Regime ◽  
Conductivity Data ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Crystalline Fraction ◽  
Transport Path

AbstractUndoped microcrystalline silicon samples deposited in the transition regime between amorphous and microcrystalline growth have been investigated by dark conductivity measurement and Raman spectroscopy. From the latter, a semi-quantitative crystalline volume fraction Xc of the sample was deduced and correlated with dark conductivity data in order to reveal possible percolation controlled transport. No threshold was observed around the critical crystalline fraction value Xc of 33%, as reported previously, but a threshold in conductivity data was found at Xc≈50%. This threshold is interpreted here speculatively as being the result of postoxidation, and not constituting an actual percolation threshold.

Influence of Hydrogen Dilution on Properties of Silicon Films Prepared by D.C. Saddle-Field Glow-Discharge: Observation of Microcrystallinity

2003 ◽  
Vol 762 ◽  
Author(s):  
T. Allen ◽  
I. Milostnaya ◽  
D. Yeghikyan ◽  
K. Leong ◽  
F. Gaspari ◽  
...  
Keyword(s):  
Glow Discharge ◽  
Gas Phase ◽  
Volume Fraction ◽  
Average Crystallite Size ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Silane Concentration ◽  
Glow Discharge Deposition

AbstractIn the D.C. saddle field glow discharge deposition the transition from amorphous to microcrystalline silicon thin films occurs when the silane concentration in the gas phase drops below 10%. We report here the results of Raman spectroscopy, SEM, TEM, and HRTEM studies of the film morphology. We estimate the average crystallite size to be in the range of 5 to 7 nm and the crystalline volume fraction of 25 to 35%.

Increase of Hydrogen-Radical Density and Improvement of The Crystalline Volume Fraction of Microcrystalline Silicon Films Prepared by Hot-Wire Assisted Pecvd Method

2000 ◽  
Vol 609 ◽  
Author(s):  
Norimitsu Yoshida ◽  
Takashi Itoh ◽  
Hiroki Inouchi ◽  
Hidekuni Harada ◽  
Katsuhiko Inagaki ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Hot Wire ◽  
Dilution Ratio ◽  
Microcrystalline Silicon ◽  
Hydrogen Dilution ◽  
Hydrogen Radical ◽  
Hydrogen Radicals ◽  
Hydrogenated Amorphous

ABSTRACTHigher crystalline Si volume fractions in hydrogenated microcrystalline silicon ( µc-Si:H) films have been achieved by the hot-wire assisted plasma enhanced chemical vapor deposition (HWA-PECVD) method compared with those in films by conventional PECVD. µc-Si:H films can also be prepared by HWA-PECVD under typical conditions used for preparing hydrogenated amorphous silicon (a-Si:H) films by PECVD, in which the hydrogen-dilution ratio (H2 / SiH4) is ∼ 10. The hot wire seems to produce hydrogen radicals. As a result, the HWA- PECVD method can control hydrogen-radical densities in the RF plasma, and this method can also control the ratio of hydrogen coverage at the surface of the film.

Effect of Hydrogen Radical on Properties of Hydrogen in Hydrogenated Microcrystalline Silicon

2000 ◽  
Vol 609 ◽  
Author(s):  
Takashi Itoh ◽  
Noriyuki Yamana ◽  
Hiroki Inouchi ◽  
Norimitsu Yoshida ◽  
Hidekuni Harada ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hot Wire ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Integrated Intensity ◽  
Hydrogen Radical ◽  
Integrated Intensities

ABSTRACTHydrogenated microcrystalline silicon (μc-Si:H) films are prepared by hot-wire assisted plasma enhanced chemical vapor deposition, which controls the hydrogen radical density by filament temperatures, Tf, without changing other conditions. The effect of hydrogen radical on the properties of incorporated hydrogen into μc-Si:H films is studied using infrared absorption and gas effusion spectroscopies. The hydrogen concentration decreases with increasing Tf. The crystalline volume fraction, Xc, increases with Tf and shows a peak at Tf of 1850 °C. Integrated intensities of the modes near 2000 and 2100 cm-1 decrease with increasing Tf. Integrated intensity of the mode near 880 cm-1 shows almost same tendency of Xc. The effect of hydrogen radical on the properties of incorporated hydrogen into μc-Si:H films is discussed.

The Study of Microcrystalline Silicon Thin Films Prepared by PECVD

2013 ◽  
Vol 537 ◽  
pp. 197-200
Author(s):  
Chun Ya Li ◽  
Hao Zhang ◽  
Jun Li ◽  
Xi Feng Li ◽  
Jian Hua Zhang
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Process Parameters ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Silicon Films ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Reaction Pressure ◽  
Silicon Thin Films

Under different growth conditions, microcrystalline silicon thin films are deposited successfully on glass substrates by the double-frequency plasma enhanced chemical vapor deposition (PECVD). We report the systematic investigation of the effect of process parameters (hydrogen dilution, substrate temperature, forward power, reaction pressure, et al.) on the growth characteristics of microcrystalline silicon thin films. Raman scattering spectra are used to analyze the crystalline condition of the films and the experimental results. Optimizing the process parameters, the highest crystalline volume fraction of microcrystalline silicon films was achieved. It is found that the crystalline volume fraction of microcrystalline silicon films reaches 72.2% at the reaction pressure of 450 Pa, H2/SiH4 flow ratio of 800sccm/10sccm, power of 400 W and substrate temperature of 350 °C.

High Quality Microcrystalline Silicon-Carbide Films Prepared by Photo-CVD Method Using Ethylene Gas as a Carbon Source

1999 ◽  
Vol 557 ◽  
Author(s):  
Seung Yeop Myong ◽  
Hyung Kew Lee ◽  
Euisik Yoon ◽  
Koeng Su Lim
Keyword(s):  
Silicon Carbide ◽  
Vapor Deposition ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Microcrystalline Silicon ◽  
Cvd Method ◽  
Hydrogen Dilution ◽  
Boron Doped

AbstractHydrogenated boron-doped microcrystalline silicon-carbide (p-μc-SiC:H) films were grown by a photo chemical vapor deposition (photo-CVD) method from silane (SiH4), hydrogen (H2), diborane (B2H6), and ethylene (C2H4) gases. Since the photo-CVD is a mild process (~10mW/cm2), we can avoid the ion damage of the film, which is inevitable during the deposition of μc-SiC:H employing conventional PECVD technique. A dark conductivity as high as 5 × 10-1 S/cm, together with an optical bandgap of 2 eV, was obtained by the C2H4 addition, which is the first approach in photo-CVD systems. From the Raman and FTIR spectra, it is clear that our p-μc-SiC:H films are made up of crystalline silicon grains embedded in amorphous silicon-carbide tissue. We investigate the role of the hydrogen dilution and ethylene addition on the electrical, optical, and structural properties of p-μc-SiC:H films.

Effect of Ge atoms on crystal structure and optoelectronic properties of hydrogenated Si–Ge films

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740010 ◽  
Author(s):  
Tianwei Li ◽  
Jianjun Zhang ◽  
Ying Ma ◽  
Yunwu Yu ◽  
Ying Zhao
Keyword(s):  
Silicon Germanium ◽  
Amorphous Matrix ◽  
Volume Fraction ◽  
Defect Density ◽  
Chemical Vapor ◽  
Radio Frequency Plasma ◽  
Microcrystalline Silicon ◽  
Bond Density ◽  
Hydrogen Dilution ◽  
Frequency Plasma

Optoelectronic and structural properties of hydrogenated microcrystalline silicon–germanium ([Formula: see text]c-Si[Formula: see text]Ge[Formula: see text]:H) alloys prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) were investigated. When the Ge atoms were predominantly incorporated in amorphous matrix, the dark and photo-conductivity decreased due to the reduced crystalline volume fraction of the Si atoms (X[Formula: see text]) and the increased Ge dangling bond density. The photosensitivity decreased monotonously with Ge incorporation under higher hydrogen dilution condition, which was attributed to the increase in both crystallization of Ge and the defect density.

Manufacturing of TFTs with High Deposition Rated Microcrystalline Silicon using Plasma Enhanced Chemical Vapor Deposition

2007 ◽  
Vol 989 ◽  
Author(s):  
Kyung-Bae Park ◽  
Ji-Sim Jung ◽  
Jong-Man Kim ◽  
Myung-kwan Ryu ◽  
Sang-Yoon Lee ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Chemical Vapor Deposition ◽  
Substrate Temperature ◽  
Threshold Voltage ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hole Mobility ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon

AbstractMicrocrystalline silicon was deposited on glass by standard plasma enhanced chemical vapor deposition using H2 diluted SiH4. Raman spectroscopy indicated a crystalline volume fraction of as high as 40% in films deposited at a substrate temperature 350oC. The deposition rate in films was as high as 10Å/sec. This process produced ¥ìc-Si TFTs with both an electron mobility of 10.9cm2/Vs, a threshold voltage of 1.2V, a subthreshold slop of 0.5V/dec at n-channel TFTs and a hole mobility of 3.2cm2/Vs, a threshold voltage of -5V, a subthreshold slop of 0.42V/dec at p-channel TFTs without post-fabrication annealing.

Effect of Hydrogen Dilution Ratio and Substrate Roughness on the Microstructure of Intrinsic Microcrystalline Silicon Thin Films

2014 ◽  
Vol 936 ◽  
pp. 202-206
Author(s):  
Bao Jun Yan ◽  
Shu Lin Liu ◽  
Xiao Wei Liu ◽  
Ting Ting Jiang
Keyword(s):  
Thin Films ◽  
Quartz Glass ◽  
Volume Fraction ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Dilution Ratio ◽  
Microcrystalline Silicon ◽  
Substrate Roughness ◽  
Coated Glass ◽  
Hydrogen Dilution

Intrinsic microcrystalline silicon (μc-Si:H) thin films were deposited on four kinds of substrates (polished quartz glass: PG, Rough quartz glass: RG, Textured SnO2:F coated glass: TG, Textured ZnO:Al coated glass: ZG) by 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) with different hydrogen dilution ratio (RH=H2/SiH4) under the pressure of 2 Torr. The film thickness, crystalline volume fraction (XC) and substrate surface roughness (Ra) were measured by surface profilometer, Raman spectra and atom force microscopy (AFM), respectively. The results revealed that with the increase of RH, the deposition rate decreased and XC increased monotonously for the films deposited on the same substrate, but the substrate Ra had an obvious impact on the film microstructure. A physical model was proposed to illustrate the growth of the μc-Si:H thin films deposited on substrates with different Ra.

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