Self-Diffusion as A Limiting Factor of a-SiGe Crystallization

1997 ◽  
Vol 469 ◽  
Author(s):  
F. Edelman ◽  
T. Raz ◽  
Y. Komem ◽  
P. Werner ◽  
W. Beyer ◽  
...  
Keyword(s):  
Grain Size ◽  
Nanocrystalline Structure ◽  
Limiting Factor ◽  
In Situ Tem ◽  
Large Area ◽  
Self Diffusion ◽  
Glass Substrates ◽  
Vacancy Generation ◽  
Nonequilibrium Vacancy ◽  
Average Grain Size

ABSTRACTHighly doped (∼1018 to 1021cm−3) polycrystalline Si1-xGex films, crystallized from amorphous (a) state at relative low temperatures, are prospective materials in a variety of applications, such as liquid-crystal displays, solar cells and integrated thermoelectric sensors on large-area glass substrates. Since the nature of the grains in the crystallized film defines properties such as carrier mobility, the nucleation and growth process of the a-SiGe films is of fundamental interest. We have studied the crystallization of undoped and highly doped (B or Ga) amorphous SiGe films. The films were deposited by RFCVD or molecular beam on oxidized (001)Si and for TEM study on cleaved NaCl. The incubation time and grain growth rate were studied by means of in situ TEM using a heating stage. The crystallization process in undoped SiGe followed Avrami relationship. An average grain size between 0.1 and 2μm was observed. However, the highly p-doped (with B or Ga) SiGe films crystallized to a stable nanocrystalline structure (grain size <10nm). The process of the a-SiGe crystallization is explained on the basis of self-diffusion. During the first stage, the nucleation of crystals is accompanied with nonequilibrium vacancy generation at the amorphous/crystalline interface. During the second stage, the growth of crystals takes place by vacancy outdiffusion which is hindered by B and Ga interaction with vacancies.

(001)-Textured Laser-Crystallized Silicon thin Films on Glass Substrates

2001 ◽  
Vol 685 ◽  
Author(s):  
M. Nerding ◽  
S. Christiansen ◽  
G. Esser ◽  
U. Urmoneit ◽  
A. Otto ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Amorphous Silicon ◽  
Continuous Wave ◽  
Defect Density ◽  
Large Area ◽  
Glass Substrates ◽  
Surface Normal ◽  
Average Grain Size ◽  
Polycrystalline Silicon Films

AbstractWe investigate the microstructure of polycrystalline silicon films (grain size, texture and grain boundary population) on glass substrates. These films are produced from amorphous silicon precursor layers by scanning the raw beam of a continuous wave Ar+- ion laser operated at a wavelength of 514 nm over the amorphous silicon thereby crystallizing it. The materials applicability for devices in large area electronics strongly depends on the orientation of the surface normal, the average grain size and the defect density and population. Transmission electron microscopy together with electron back-scattering diffraction analysis of the crystallized layers reveal grain widths of about 10μm and grain lengths of several 10 μm. Under certain procesing conditions a preferred (001)-surface normal orientation (texture) forms. The grain boundary population is dominated in the textured films by coincidence boundaries, essentially twin boundaries of first and second order as well as Σ=5 boundaries.

Effect of Annealing on Nanocrystalline Structure of Nb3Sn Diffusion Layers in Composites with Internal Tin Sources

2010 ◽  
Vol 297-301 ◽  
pp. 126-131 ◽  
Author(s):  
E.N. Popova ◽  
Vladimir V. Popov ◽  
E.P. Romanov ◽  
S.V. Sudareva ◽  
L.V. Elohina ◽  
...  
Keyword(s):  
Grain Size ◽  
Carrying Capacity ◽  
Nanocrystalline Structure ◽  
Diffusion Annealing ◽  
External Diameter ◽  
High Temperature Annealing ◽  
Grain Sizes ◽  
Diffusion Layers ◽  
Average Grain Size ◽  
Complete Transformation

Multifilamentary Nb3Sn-based superconducting composites manufactured by an internal-tin method have been studied by transmission (TEM) and scanning (SEM) electron microscopy. The main goal of this study is to reveal the effect of diffusion annealing regimes as well as the external diameter of the wires on the structure of nanocrystalline Nb3Sn layers (average grain size, grain size distribution, layer thickness, amount of Sn, etc.). It is demonstrated that multistep diffusion annealing results in quite a complete transformation of Nb filaments into Nb3Sn though some amount of the residual Nb remains in the filaments center. With an external diameter decrease the superconducting layers structure has been found to refine and get somewhat more uniform. An additional high-temperature annealing results in marked growth of Nb3Sn grain sizes and their scattering in sizes, which may negatively affect the current-carrying capacity of a wire.

Structural and Morphological Studies of Cadmium Sulfide Nanostructures

2013 ◽  
Vol 795 ◽  
pp. 228-232 ◽  
Author(s):  
Abdulwahab S.Z. Lahewil ◽  
Y. Al-Douri ◽  
U. Hashim ◽  
Naser Mahmoud Ahmed
Keyword(s):  
Grain Size ◽  
Cadmium Sulfide ◽  
Spin Coating ◽  
Sol Gel ◽  
Theoretical Data ◽  
Glass Substrates ◽  
Morphological Studies ◽  
Average Grain Size ◽  
Cds Nanostructures ◽  
Semiconductor Properties

Cadmium sulfide (CdS) nanostructures were prepared with different spin coating speed 1000 and 3000 rpm and molarities of Cd:S to be 1.2 to 0.01 mol/L using sol-gel spin coating technique. It is found that the average grain size of CdS nanostructures deposited on glass substrates at 1000 and 3000 rpm is 43 to 4 nm respectively. The effect of grain size on the semiconductor properties are in agreement with experimental and theoretical data.

scholarly journals Performance of a Nano PbS/Si Hetrojunction Deposited by Chemical Spray Pyrolysis

2015 ◽  
Vol 51 ◽  
pp. 13-16 ◽  
Author(s):  
Ali M. Mousa ◽  
Karem H. Jawad
Keyword(s):  
Grain Size ◽  
Blue Shift ◽  
Chemical Spray Pyrolysis ◽  
Xrd Pattern ◽  
Glass Substrates ◽  
Current Voltage ◽  
Average Grain Size ◽  
Wide Range ◽  
P Type ◽  
Nanocrystalline Thin Films

Deposition of polycrystalline Lead sulfide nanothin films onto Si and glass substrates at temperatures (200-300 °C) was carried out by chemical spraying route using optimized preparative conditions. The XRD pattern confirmed the formation of PbS semiconducting films with orthorhombic structure. The electrical and optical properties of the nanocrystalline thin films were studied aiming to better understanding for the electrical and opto-electrical properties of a hetrojunction with p-type Si. It was found that, the average grain size of PbS in the films was between 4 nm and 7 nm. The band gap was also calculated from the absorption co-efficient curves and showed a blue shift due to the grain size of the nanoPbS in the films. The current-voltage (I-V) and photoresponse characteristics were obtained with different illumination intensities. The detector exhibits an evident wide-range spectral responsivity

scholarly journals Tuning The Crystallographic Structure And Morphology Of Nanocrystalline CaB6 Films Deposited By DC Magnetron Sputtering

2015 ◽  
Vol 60 (2) ◽  
pp. 897-901 ◽  
Author(s):  
L. Zhang ◽  
G. Zhao ◽  
H. Liu ◽  
G. Min ◽  
H. Yu
Keyword(s):  
Grain Size ◽  
Magnetron Sputtering ◽  
Energy Dispersive Spectrometer ◽  
Argon Pressure ◽  
Raman Shift ◽  
Crystallographic Structure ◽  
Dc Magnetron Sputtering ◽  
Glass Substrates ◽  
Average Grain Size ◽  
Crystallite Sizes

Abstract Through changing the argon pressure, CaB6 films with different crystallographic orientation and morphology on glass substrates were prepared by direct current (DC) magnetron sputtering method. The film textures, crystallite sizes, composition and morphology were investigated by a spectrum of characterizing techniques in terms of X-ray diffraction (XRD), field emission scanning electron microscopy with energy dispersive spectrometer (FESEM-EDS), atomic force microscopy (AFM), Raman shift spectroscopy. The influence of argon pressure on microstructure was studied. The average grain size increased with the argon pressure increasing from 0.8 Pa to 1.5 Pa. Meanwhile, the dominant crystal face changed from (110) to (100). Then the grain size decreased when the argon pressure increased to 2.0 Pa. The surface morphology evolved from typical cauliflower-like nanocrystalline clusters to faceted rectangular pyramids. It was found that considerable amount of argon atoms were trapped in the films. The formation process of CaB6 films was also analyzed in this paper.

Effect of Electron Irradiation on Nanocrystallization of Fe-Nd-B Amorphous Alloys

2006 ◽  
Vol 512 ◽  
pp. 107-110 ◽  
Author(s):  
Akihiro Nino ◽  
Takeshi Nagase ◽  
Yukichi Umakoshi
Keyword(s):  
Grain Size ◽  
Amorphous Phase ◽  
Electron Irradiation ◽  
Amorphous Alloys ◽  
Single Phase ◽  
Nanocrystalline Structure ◽  
Rapid Quenching ◽  
Thermal Crystallization ◽  
Average Grain Size ◽  
Induced Crystallization

Formation of a nanocrystalline structure through rapid solidification, thermal crystallization and electron irradiation induced crystallization was investigated in Fe-Nd-B alloys. A nanocrystalline structure was obtained by rapid quenching of the melt in a Fe86Nd9B5 alloy, while an amorphous single phase was formed in a Fe77Nd4.5B18.5 alloy. In the latter alloy, a nanocrystalline structure was obtained by thermal crystallization and electron irradiation induced crystallization of the amorphous phase. The average grain size of the precipitate obtained by irradiation at 298 K was about 8 nm, which is much smaller than that obtained during thermal crystallization. Results indicate that electron irradiation is effective for obtaining a novel nanocrystalline structure in Fe-Nd-B alloys.

Low Temperature Metal-Free Fabrication of polycrystalline Si and Ge TFTs by PECVD Hydrogenation

2005 ◽  
Vol 862 ◽  
Author(s):  
Pouya Hashemi ◽  
Jaber Derakhshandeh ◽  
Bahman Hekmatshoar ◽  
Shamsoddin Mohajerzadeh ◽  
Yaser Abdi ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Thin Film Transistors ◽  
Hydrogen Plasma ◽  
Plasma Power ◽  
Large Area ◽  
Metal Free ◽  
Glass Substrates ◽  
Annealing Step ◽  
Average Grain Size ◽  
Metal Incorporation

AbstractPoly-crystalline Si and Ge layers were grown at low temperatures on glass substrates by successive hydrogenation and annealing steps, with no need to any metal incorporation. Hydrogenation is performed in an RF-PECVD apparatus with different powers of hydrogen plasma and the annealing step is carried out in the same system in N2 ambient. This leads to formation of granular Si and Ge structures with average grain size of less than 100nm at temperatures as low as 250°C and 150°C, respectively. The effect of hydrogen plasma power at various temperatures on the crystallinity of the layers has been studied by SEM and TEM analyzes. Successive hydrogenation and annealing at respective temperatures of 150°C and 200°C for Ge layer and 300°C for Si layer would result in a device-quality polycrystalline Ge and Si layers which have been employed for fabrication of thin-film transistors. These TFTs show the mobility of 80cm2/Vs and 4cm2/Vs and ON/OFF ratio of more than 103 and 5×104 for Ge and Si, indicating the feasibility of this technique for applications in large-area electronics.

Improving the Reliability of EBSD-Based Texture Analysis by a New Large Area Mapping Technique

2011 ◽  
Vol 702-703 ◽  
pp. 566-569
Author(s):  
Kemal Davut ◽  
Stefan Zaefferer
Keyword(s):  
Grain Size ◽  
Mapping Technique ◽  
Small Step ◽  
Large Area ◽  
Step Size ◽  
Average Grain Size ◽  
Very Large Datasets ◽  
Ebsd Technique ◽  
Xrd Techniques ◽  
Statistical Representativeness

The relevance of EBSD-based investigations for statements on the macroscopic or mesoscopic behavior of materials is critically relying on the statistical representativeness of the data. Particularly, the statistical reliability of the EBSD-based results (e.g. texture, phase fraction or grain size) remains an open question since the areas observed by the EBSD technique are quite small compared to XRD techniques. It has already been shown that covering larger areas and probing more grains with the help of large step sizes is beneficial in terms of representativeness [1]. On the other hand, small step sizes are beneficial in terms of grain reconstruction and data clean-up. However, step sizes significantly smaller than the average grain size of the material lead to either covered areas or number of probed grains being too small to be representative or to very large datasets and correspondingly long measurement times. In this contribution, the benefits of a new mapping technique [1] that joins the advantages of large and small step size measurements will be demonstrated. The representativeness of the EBSD datasets obtained by classical and this new mapping techniques were compared by calculating the pole figure symmetries of a TRIP steel. The results show that the proposed mapping technique significantly improves the reliability and representativeness of EBSD-based texture measurements.

Properties of Hexagonal Wurtzite Mg0.33Zn0.67O Films on Quartz Glass Substrates

2011 ◽  
Vol 337 ◽  
pp. 612-615
Author(s):  
Quan Sheng Liu ◽  
Xi Yan Zhang ◽  
Xiao Chun Wang ◽  
Zhao Hui Bai ◽  
Neng Li Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Absorption Spectrum ◽  
Quartz Glass ◽  
Sol Gel ◽  
Hexagonal Wurtzite Structure ◽  
Xrd Analysis ◽  
Excitation Peak ◽  
Lattice Constants ◽  
Glass Substrates ◽  
Average Grain Size

Mg0.33Zn0.67Ofilms were prepared on quartz glass substrates by Sol-Gel method. Structures and optical properties of Mg0.33Zn0.67Ofilms were studied. The results of XRD analysis indicates that the Mg0.33Zn0.67Ofilm is hexagonal wurtzite structure and the lattice constants a and c are 0.3265nm and 0.5218 nm respectively. Lattice constants a and c of the Mg0.33Zn0.67O film increased because of the addition of Mg. The image of SEM shows that the Mg0.33Zn0.67O film is homogeneous and its average grain size is about 40nm. The absorption spectrum of the sample reveals that the absorption edge of Mg0.33Zn0.67O film located at 312.3nm and the corresponding forbidden band width is 3.97eV. is by three peaks ，which located at 383.9nm，442.6nm and 532.9nm respectively，constitute the luminescence spectrum of the film. The excitation peak located at 379.9nm.

Synthesis of Corrugated Structured N Type Pbs Thin Film

2012 ◽  
Vol 500 ◽  
pp. 118-122 ◽  
Author(s):  
E.I. Anila ◽  
K.J. Saji ◽  
U.S. Sajeev
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Xrd Analysis ◽  
Dip Coating ◽  
Pbs Nanoparticles ◽  
Glass Substrates ◽  
Average Grain Size ◽  
Type Band ◽  
Corrugated Structure ◽  
Power Measurements

PbS thin films with corrugated structure were synthesized on glass substrates by dip coating. The surface of the films was found to be corrugated. XRD analysis confirmed the formation of crystalline PbS nanoparticles with average grain size 14nm. From thermo power measurements, the conductivity of the samples was found to be of n type. Band gap of the films was estimated as 1.7eV from absorption spectra.

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