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.

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.

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.

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.

Influence of Substrate Temperature and Hydrogen Dilution Ratio on the Properties of Nanocrystalline Silicon Thin Films Grown by Hot-Wire Chemical Vapor Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
H.R. Moutinho ◽  
C.-S. Jiang ◽  
B. Nelson ◽  
Y. Xu ◽  
J. Perkins ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Seed Layer ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Dilution Ratio ◽  
Crystal Silicon ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Influence Of Substrate

AbstractWe have studied the influence of substrate temperature and hydrogen dilution ratio on the properties of silicon thin films deposited on single-crystal silicon and glass substrates. We varied the initial substrate temperature from 200° to 400°C and the dilution ratio from 10 to 100. We also studied the effectiveness of the use of a seed layer to increase the crystallinity of the films. The films were analyzed by atomic force microscopy, X-ray diffraction, Raman spectroscopy, and transmission and scanning electron microscopy. We found that as the dilution ratio is increased, the films go from amorphous, to a mixture of amorphous and crystalline, to nanocrystalline. The effect of substrate temperature is to increase the amount of crystallinity in the film for a given dilution ratio. We found that the use of a seed layer has limited effects and is important only for low values of dilution ratio and substrate temperature, when the films have large amounts of the amorphous phase.

scholarly journals Structural Characterization of SiF4, SiH4 and H2 Hot-Wire-Grown Microcrystalline Silicon Thin Films with Large Grains

2001 ◽  
Vol 664 ◽  
Author(s):  
J. J. Gutierrez ◽  
C. E. Inglefield ◽  
C. P. An ◽  
M. C. DeLong ◽  
P. C. Taylor ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Annealing Treatment ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Hot Wire ◽  
Microcrystalline Silicon ◽  
Crystal Volume

ABSTRACTIn this paper, we present a comprehensive study of microcrystalline silicon thin film samples deposited by a novel growth process intended to maximize their grain size and crystal volume fraction. Using Atomic Force Microscopy, Raman spectroscopy, and x ray diffraction the structural properties of these samples were characterized qualitatively and quantitatively. Samples were grown using a Hot-Wire Chemical Vapor Deposition process with or without a post-growth hot-wire annealing treatment. During Hot-Wire Chemical Vapor Deposition, SiF4 is used along with SiH4 and H2 to grow the thin films. After growth, some samples received an annealing treatment with only SiF4 and H2 present. These samples were compared to each other in order to determine the deposition conditions that maximize grain size. Large microcrystalline grains were found to be aggregates of much smaller crystallites whose size is nearly independent of deposition type and post-annealing treatment. Thin films deposited using the deposition process with SiF4 partial flow rate of 2 sccm and post-growth annealing treatment had the largest aggregate grains ∼.5 µm and relatively high crystal volume fraction.

Amorphous-to-Microcrystalline Silicon Transition in Hot-Wire Chemical Vapor Deposition

1995 ◽  
Vol 377 ◽  
Author(s):  
P. Brogueira ◽  
V. Chu ◽  
J. P. Conde
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Hot Wire ◽  
Microcrystalline Silicon ◽  
Crystalline Fraction ◽  
Hydrogen Dilution ◽  
Process Pressure ◽  
Silicon Growth

ABSTRACTThe conductivity and the structural properties of thin films deposited by Hot-Wire Chemical Vapor Deposition (HW-CVD) from silane and hydrogen at a substrate temperature of 220 °C are shown to be strongly dependent on the filament temperature, Tfil, and process pressure, p. Amorphous silicon films are obtained at low pressures, p < 3 × 10−2Torr, for Tfil ∼ 1900 °C and FH2 = FSiH4. At this TfilJU, high deposition rates are observed, both with and without hydrogen dilution, and no silicon was deposited on the filaments. At Tfil ∼ 1500 °C, a transition from a-Si:H for p > 0.3 Torr to microcrystalline silicon (μc-Si:H) for p < 0.1 Torr occurs. In this temperature regime, silicon growth on the filaments is observed. /ic-Si:H growth both without hydrogen dilution and also in very thin films (∼ 0.05 μm) is achieved. Raman and X-Ray spectra give typical grain sizes of 10 – 20 nm, with a crystalline fraction higher than 50%. For both, Tju ∼ 1500 °C, p > 0.3 Torr and Tfil ∼ 1900 °C and p ∼ 2.7 × 10−2Torr, an increase of the crystalline fraction from 0 to ∼ 30% is observed when the hydrogen dilution, FH2/FSiH4, increases from 1 to > 4.

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.

Effect of Hydrogen Dilution on Properties of Microcrystalline Silicon Thin Films Prepared by VHF-PECVD

2013 ◽  
Vol 652-654 ◽  
pp. 1739-1742
Author(s):  
Xia Wu ◽  
Long Gu ◽  
Ji Sen Zhang ◽  
Hui Dong Yang
Keyword(s):  
Thin Films ◽  
Amorphous Silicon ◽  
Deposition Rate ◽  
Structural Characteristics ◽  
Silicon Film ◽  
Crystallization Rate ◽  
Dilution Ratio ◽  
Microcrystalline Silicon ◽  
Silicon Thin Films ◽  
Hydrogen Dilution

Microcrystalline silicon thin films were deposited on glass substrates by VHF-PECVD varying the ratio of hydrogen dilution from 88% to 98%. The structural characteristics, deposition rate and photosensitivity of the films were investigated. With the improvement of the hydrogen dilution ratio, crystallization rate of the films had been improved which was much more stable than amorphous silicon that the films transmit from amorphous silicon to microcrystalline silicon. However the deposition rate had been reduced with the increase of the hydrogen dilution and the highest deposition rate was 0.43nm/s. The samples showed a downward trend of photosensitivity with optical and dark conductivity both decreasing first then increasing. Thus suitable hydrogen dilution ratio should be chosen according to the different needs in preparation of microcrystalline silicon film.

Real Time Optics of p-Type Microcrystalline Silicon Deposition On Specular and Textured ZnO-Coated Glass

2000 ◽  
Vol 609 ◽  
Author(s):  
Pablo I. Rovira ◽  
Andre S. Ferlauto ◽  
Randy J. Koval ◽  
Christopher R. Wronski ◽  
Robert W. Collins ◽  
...  
Keyword(s):  
Real Time ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Phase Evolution ◽  
High Density ◽  
Dilution Ratio ◽  
Microcrystalline Silicon ◽  
Coated Glass ◽  
Induction Periods ◽  
P Type

ABSTRACTIn this study, we optimize the plasma-enhanced chemical vapor deposition (PECVD) process to achieve high-density nucleation of single-phase microcrystalline silicon (µc-Si:H) p-type layers on zinc oxide (ZnO) surfaces at 200 °C for applications in amorphous silicon (a-Si:H) based p-i-n solar cells. The phase evolution of the Si:H p-layers on specular ZnO-coated glass substrates is characterized using real time spectroscopic ellipsometry (RTSE). The resulting evolutionary phase diagram depicts the accumulated film thickness at which the amorphous-to- microcrystalline (→µc) transition occurs versus the H2-dilution ratio, with all other parameters fixed. Guided by this diagram, we find that high-density microcrystallite nucleation and fully- coalesced µc-Si:H p-layers ∼100 Å thick can be obtained on specular ZnO at 200 Å using a B(CH3)3 doping gas flow ratio of D=[B(CH3)3]/[SiH4]=0.02 and an optimized H2-dilution ratio of R=[H2]/SiH4]=200. Lower H2-dilution levels (R<160) generate purely amorphous or mixed (a+µc) phases, and higher dilution levels (R>200) generate longer induction periods, low-density nucleation, and incomplete coalescence of microcrystallites even after ∼100 Å. The time evolution of the microstructure and the resulting dielectric functions as determined by RTSE are similar for optimized µc-Si:H p-layers ∼200 Å thick prepared on specular and textured ZnO surfaces, indicating that the substrate texturing does not necessitate process reoptimization.

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