scholarly journals Comparative Study on the Quality of Microcrystalline and Epitaxial Silicon Films Produced by PECVD Using Identical SiF4 Based Process Conditions

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6947
Author(s):  
Mario Moreno ◽  
Arturo Ponce ◽  
Arturo Galindo ◽  
Eduardo Ortega ◽  
Alfredo Morales ◽  
...  
Keyword(s):  
Thin Film ◽  
Volume Fraction ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Process Conditions ◽  
Epitaxial Silicon ◽  
Microcrystalline Silicon ◽  
Transmission Electron ◽  
Si Films

Hydrogenated microcrystalline silicon (µc-Si:H) and epitaxial silicon (epi-Si) films have been produced from SiF4, H2 and Ar mixtures by plasma enhanced chemical vapor deposition (PECVD) at 200 °C. Here, both films were produced using identical deposition conditions, to determine if the conditions for producing µc-Si with the largest crystalline fraction (XC), will also result in epi-Si films that encompass the best quality and largest crystalline silicon (c-Si) fraction. Both characteristics are of importance for the development of thin film transistors (TFTs), thin film solar cells and novel 3D devices since epi-Si films can be grown or etched in a selective manner. Therefore, we have distinguished that the H2/SiF4 ratio affects the XC of µc-Si, the c-Si fraction in epi-Si films, and the structure of the epi-Si/c-Si interface. Raman and UV-Vis ellipsometry were used to evaluate the crystalline volume fraction (Xc) and composition of the deposited layers, while the structure of the films were inspected by high resolution transmission electron microscopy (HRTEM). Notably, the conditions for producing µc-Si with the largest XC are different in comparison to the fabrication conditions of epi-Si films with the best quality and largest c-Si fraction.

Microstructure and Electric Transport Characteristic of Microcrystalline Silicon Films Fabricated by Very High Frequency Plasma Enhanced Chemical Vapor Deposition

2010 ◽  
Vol 663-665 ◽  
pp. 600-603
Author(s):  
Xiang Wang ◽  
Rui Huang ◽  
Jie Song ◽  
Yan Qing Guo ◽  
Chao Song ◽  
...  
Keyword(s):  
High Frequency ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Microcrystalline Silicon ◽  
Very High Frequency ◽  
Hydrogen Flow ◽  
Transmission Electron ◽  
High Frequency Plasma ◽  
Frequency Plasma ◽  
Very High

Microcrystalline silicon (μc-Si:H) film deposited on silicon oxide in a very high frequency plasma enhanced chemical vapor deposition with highly H2 dilution of SiH4 has been investigated by Raman spectroscopy and high resolution transmission electron microscopy. Raman spectroscopy results show that the crystalline volume fraction increases with increasing the hydrogen flow rate and for the hydrogen flow rate of 160 sccm, the crystalline volume fraction reaches to 67.5%. Nearly parallel columnar structures with complex microstructure are found from cross-sectional transmission electron microscopy images of the film. The temperature depend dark conductivity and activation energy are studied in order to investigate the electronic transport processes in the nc-Si films.

Plasma Deposition and Interface Control in Low Temperature Processing of Thin Film Solar Cells

1997 ◽  
Vol 485 ◽  
Author(s):  
B. Jagannathan ◽  
W. A. Anderson
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Carrier Transport ◽  
Crystalline Silicon ◽  
Plasma Deposition ◽  
Microcrystalline Silicon ◽  
Interface Control ◽  
Electro Optic ◽  
Low Temperature Processing ◽  
Si Films

AbstractPlasma deposition of thin silicon films with a variable microstructure and controlled interface formation techniques are being developed for thin film silicon/polycrystalline silicon solar cells. Low hydrogen content amorphous (a-Si) or microcrystalline silicon (μ c-Si) films were obtained by controlling the H2 dilution of 2% SiH4/He in a microwave ECR discharge. The films were characterized for structural and electro-optic properties. Junction creation for solar cells was investigated by depositing single or multilayers of the film silicon onto crystalline silicon (c-Si). Effort to improve carrier transport and photovoltaic (PV) properties was pursued through interface modifications effected by varying the microstructure of the layer in contact with the substrate. Cells with 7% conversion efficiency (No A/R) were obtained for an a-Si/c-Si heterojunction configuration. Improved carrier transport and PV properties (9% ef ficient) were achieved by inserting a thin μ c-Si layer in the above structure.

Onset of Misfit Dislocation Generation in As-Grown and Annealed Sil-XGex/Si Films

1988 ◽  
Vol 130 ◽  
Author(s):  
M. P. Scott ◽  
S. S. Laderman ◽  
T. I. Kamins ◽  
S. J. Rosner ◽  
K. Nauka ◽  
...  
Keyword(s):  
Misfit Dislocation ◽  
Chemical Vapor ◽  
Misfit Dislocations ◽  
Epitaxial Silicon ◽  
Dislocation Generation ◽  
Transmission Electron ◽  
Vapor Deposition Technique ◽  
Si Films ◽  
Reaction Processing ◽  
Thermal Stability Of

AbstractX-ray topography and transmission electron microscopy were used to quantify misfit-dislocation spacings in as-grown Si1-xGex films formed by Limited Reaction Processing (LRP), which is a chemical vapor deposition technique. These analysis techniques were also used to study dislocation formation during annealing of material grown by both LRP and by molecular beam epitaxy (MBE). The thickness at which misfit dislocations first appear in as-grown material was similar for both growth techniques. The thermal stability of capped and uncapped films was also investigated after rapid thermal annealing in the range of 625 to 1000°C. Significantly fewer misfit dislocations were observed in samples containing an epitaxial silicon cap. Some differences in the number of misfit dislocation generated in CVD and MBE films were observed after annealing uncapped layers at temperatures between 625 and 825°C.

Microtwin morphology and density for silicon on sapphire

1988 ◽  
Vol 46 ◽  
pp. 890-891
Author(s):  
M. E. Twigg ◽  
E. D. Richmond
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Density Profile ◽  
Trace Analysis ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Transmission Electron

In order to understand the influence of various growth and processing procedures on the quality of silicon grown on sapphire (SOS), one needs a way to measure microtwin density as a function of distance from the interface. In previous studies, however, the technique best suited for determining such a density profile, transmission electron microscopy (TEM), has been applied to this problem in a relatively qualitative manner. We have chosen to apply TEM in a more quantitative fashion to this problem by keying our observations to microtwin morphology as determined by trace analysis and stereomicroscopy (Fig.1). These observations indicate that the microtwins occuring in SOS grown by chemical vapor depostition (CVD) are faceted and grow contiguously from the interface. The volume fraction of silicon occuring as microtwins does not decrease away from the interface at as large a rate as indicated by previous TEM studies (Fig.2). Instead, the decrease in the number of twins away from the interface appears to be balanced by an increase in twin size.

The relaxation of compressive biaxial strains in SOS via microtwins

1989 ◽  
Vol 47 ◽  
pp. 608-609
Author(s):  
M. E. Twigg ◽  
E. D. Richmond ◽  
J. G. Pellegrino
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Molecular Beam Epitaxy ◽  
Compressive Stress ◽  
Vapor Deposition ◽  
Partial Dislocation ◽  
Molecular Beam ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Silicon Thin Film

For heteroepitaxial systems, such as silicon on sapphire (SOS), microtwins occur in significant numbers and are thought to contribute to strain relief in the silicon thin film. The size of this contribution can be assessed from TEM measurements, of the differential volume fraction of microtwins, dV/dν (the derivative of the microtwin volume V with respect to the film volume ν), for SOS grown by both chemical vapor deposition (CVD) and molecular beam epitaxy (MBE).In a (001) silicon thin film subjected to compressive stress along the [100] axis , this stress can be relieved by four twinning systems: a/6[211]/( lll), a/6(21l]/(l1l), a/6[21l] /( l1l), and a/6(2ll)/(1ll).3 For the a/6[211]/(1ll) system, the glide of a single a/6[2ll] twinning partial dislocation draws the two halves of the crystal, separated by the microtwin, closer together by a/3.

The SiNx films process research by plasma-enhanced chemical vapor deposition in crystalline silicon solar cells

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744101 ◽  
Author(s):  
Bitao Chen ◽  
Yingke Zhang ◽  
Qiuping Ouyang ◽  
Fei Chen ◽  
Xinghua Zhan ◽  
...  
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Solar Cell ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Silicon Solar Cell ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Double Layers ◽  
Crystalline Silicon Solar Cell

SiNx thin film has been widely used in crystalline silicon solar cell production because of the good anti-reflection and passivation effect. We can effectively optimize the cells performance by plasma-enhanced chemical vapor deposition (PECVD) method to change deposition conditions such as temperature, gas flow ratio, etc. In this paper, we deposit a new layer of SiNx thin film on the basis of double-layers process. By changing the process parameters, the compactness of thin films is improved effectively. The NH3passivation technology is augmented in a creative way, which improves the minority carrier lifetime. In sight of this, a significant increase is generated in the photoelectric performance of crystalline silicon solar cell.

Precursor design and engineering for low-temperature deposition of gate dielectrics for thin film transistors

2011 ◽  
Vol 1287 ◽  
Author(s):  
Anupama Mallikarjunan ◽  
Laura M Matz ◽  
Andrew D Johnson ◽  
Raymond N Vrtis ◽  
Manchao Xiao ◽  
...  
Keyword(s):  
Thin Film ◽  
Low Temperature ◽  
Thin Film Transistors ◽  
Moisture Absorption ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Silicon Oxycarbide ◽  
Process Conditions ◽  
Structure Property ◽  
Oh Groups

ABSTRACTThe electrical and physical quality of gate and passivation dielectrics significantly impacts the device performance of thin film transistors (TFTs). The passivation dielectric also needs to act as a barrier to protect the TFT device. As low temperature TFT processing becomes a requirement for novel applications and plastic substrates, there is a need for materials innovation that enables high quality plasma enhanced chemical vapor deposition (PECVD) gate dielectric deposition. In this context, this paper discusses structure-property relationships and strategies for precursor development in silicon nitride, silicon oxycarbide (SiOC) and silicon oxide films. Experiments with passivation SiOC films demonstrate the benefit of a superior precursor (LkB-500) and standard process optimization to enable lower temperature depositions. For gate SiO2 deposition (that are used with polysilicon TFTs for example), organosilicon precursors containing different types and amounts of Si, C, O and H bonding were experimentally compared to the industry standard TEOS (tetraethoxysilane) at different process conditions and temperatures. Major differences were identified in film quality especially wet etch rate or WER (correlating to film density) and dielectric constant (k) values (correlating to moisture absorption). Gate quality SiO2 films can be deposited by choosing precursors that can minimize residual Si-OH groups and enable higher density stable moisture-free films. For e.g., the optimized precursor AP-LTO® 770 is clearly better than TEOS for low temperature PECVD depositions based on density, WER, k charge density (measured by flatband voltage or Vfb); and leakage and breakdown voltage (Vbd) measurements. The design and development of such novel precursors is a key factor to successfully enable manufacturing of advanced low temperature processed devices.

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.

Stress in Hydrogenated Microcrystalline Silicon Thin Films

1999 ◽  
Vol 557 ◽  
Author(s):  
D. Peiró ◽  
C. Voz ◽  
J. Bertomeu ◽  
J. Andreu ◽  
E. Martínez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hot Wire ◽  
X Ray Diffraction ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Silicon Thin Films ◽  
Abrupt Changes

AbstractHydrogenated microcrystalline silicon films have been obtained by hot-wire chemical vapor deposition (HWCVD) in a silane and hydrogen mixture at low pressure (<5 × 10-2 mbar). The structure of the samples and the residual stress were characterised by X- ray diffraction (XRD). Raman spectroscopy was used to estimate the volume fraction of the crystalline phase, which is in the range of 86 % to 98%. The stress values range between 150 and -140 MPa. The mechanical properties were studied by nanoindentation. Unlike monocrystalline wafers, there is no evidence of abrupt changes in the force-penetration plot, which have been attributed to a pressure-induced phase transition. The hardness was 12.5 GPa for the best samples, which is close to that obtained for silicon wafers.

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