scholarly journals Hydrogenated Nanocrystalline Silicon Thin Films Prepared by Hot-Wire Method with Varied Process Pressure

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
V. S. Waman ◽  
A. M. Funde ◽  
M. M. Kamble ◽  
M. R. Pramod ◽  
R. R. Hawaldar ◽  
...  
Keyword(s):  
Optical Properties ◽  
Cost Effective ◽  
Nanocrystalline Silicon ◽  
Hot Wire ◽  
Structural And Optical Properties ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Process Pressure ◽  
Vis Spectroscopy ◽  
Wire Method

Hydrogenated nanocrystalline silicon films were prepared by hot-wire method at low substrate temperature (200∘C) without hydrogen dilution of silane (SiH4). A variety of techniques, including Raman spectroscopy, low angle X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), and UV-visible (UV-Vis) spectroscopy, were used to characterize these films for structural and optical properties. Films are grown at reasonably high deposition rates (>15 Å/s), which are very much appreciated for the fabrication of cost effective devices. Different crystalline fractions (from 2.5% to 63%) and crystallite size (3.6–6.0 nm) can be achieved by controlling the process pressure. It is observed that with increase in process pressure, the hydrogen bonding in the films shifts from Si–H to Si–H2and(Si–H2)ncomplexes. The band gaps of the films are found in the range 1.83–2.11 eV, whereas the hydrogen content remains <9 at.% over the entire range of process pressure studied. The ease of depositing films with tunable band gap is useful for fabrication of tandem solar cells. A correlation between structural and optical properties has been found and discussed in detail.

Effects of high hydrogen dilution ratio on optical properties of hydrogenated nanocrystalline silicon thin films

2011 ◽  
Vol 257 (23) ◽  
pp. 9840-9845 ◽  
Author(s):  
Liqiang Guo ◽  
Jianning Ding ◽  
Jichang Yang ◽  
Guanggui Cheng ◽  
Zhiyong Ling ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Nanocrystalline Silicon ◽  
Dilution Ratio ◽  
High Hydrogen ◽  
Silicon Thin Films ◽  
Hydrogen Dilution

scholarly journals Fe2O3 Modified Physical, Structural and Optical Properties of Bismuth Silicate Glasses

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Rajesh Parmar ◽  
R. S. Kundu ◽  
R. Punia ◽  
N. Kishore ◽  
P. Aghamkar
Keyword(s):  
Optical Properties ◽  
Silicate Glasses ◽  
Bandgap Energy ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Scanning Calorimetry ◽  
Bismuth Silicate ◽  
Vis Spectroscopy ◽  
Amorphous Nature ◽  
Optical Bandgap Energy

Iron-containing bismuth silicate glasses with compositions 60SiO2·(100−x)Bi2O3·xFe2O3 have been prepared by conventional melt-quenching technique. The amorphous nature of the glass samples has been ascertained by the X-ray diffraction. The density (d) has been measured using Archimedes principle, molar volume (Vm) has also been estimated, and both are observed to decrease with the increase in iron content. The glass transition temperature (Tg) of these iron bismuth silicate glasses has been determined using differential scanning calorimetry (DSC) technique, and it increases with the increase in Fe2O3 content. The IR spectra of these glasses consist mainly of [BiO6], [BiO3], and [SiO4] structural units. The optical properties are measured using UV-VIS spectroscopy. The optical bandgap energy (Eop) is observed to decrease with the increase in Fe2O3 content, whereas reverse trend is observed for refractive index.

Allotropic Modification Induced by Co60 Radiation on the Structural and Optical Properties of Aromatic Polymers

2011 ◽  
Vol 383-390 ◽  
pp. 3264-3271
Author(s):  
Singh Siddhartha ◽  
Suveda Aarya ◽  
A.K. Srivastava ◽  
Monika Mishra ◽  
M.A. Wahab
Keyword(s):  
Optical Properties ◽  
Structural And Optical Properties ◽  
Visible Absorption ◽  
Peak Intensity ◽  
Allotropic Modification ◽  
Vis Spectroscopy ◽  
Aromatic Polymers ◽  
Uv Visible ◽  
Indirect Band Gap ◽  
Gamma Irradiated

The structural and optical properties of virgin and gamma rays irradiation on aromatic polymers (PET, PES and Kapton) at various doses varying from 16 to 300kGy. The optical and Structural studies have been observed by using UV-VIS Spectroscopy and Powder X- Ray Diffration techniques. The diffraction pattern of virgin samples shows that polymers are semi crystalline in nature. But due to irradiation, the overall crystalline peak intensity and crystallite size is found to be increased with increasing dose. The UV-Visible absorption spectra show the existence of the maximum absorption, their shifting and broadening as a result of gamma irradiation has been discussed. Finally the value of direct and indirect band gap in virgin and gamma irradiated on aromatic polymers has been decreased.

STRUCTURAL AND OPTICAL PROPERTIES OF NANOCRYSTALLINE SILICON FILMS DEPOSITED AT 150°C

2002 ◽  
Vol 16 (01n02) ◽  
pp. 219-226 ◽  
Author(s):  
ATIF MOSSAD ALI ◽  
YASUHIKO SAKAI ◽  
NOBORU ADACHI ◽  
TAKAO INOKUMA ◽  
YOSHIHIRO KURATA ◽  
...  
Keyword(s):  
Optical Properties ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Close Correlation ◽  
Nanocrystalline Silicon ◽  
Nanocrystalline Phase ◽  
Structural And Optical Properties ◽  
Average Grain Size ◽  
Si Films ◽  
Two Peaks

Nanocrystalline silicon (nc-Si) films were deposited by plasma-enhanced chemical vapor deposition from a SiH 4- H 2 gas mixture. The structural and optical properties of nc-Si films were examined by changing the flow rates of a H 2 gas or a SiF 4 gas diluted by He. The structural change from an amorphous to a nanocrystalline phase was found at H 2 flow rate ([ H 2]) higher than 3 sccm under [ SiF 4/ He ] = 0 sccm and/or by adding SiF 4/ He under [ H 2] = 0 sccm . However, under [ H 2] = 3 sccm, the maximum crystallinity (crystalline volume fraction, ρ) was observed at around [ SiF 4/ He ] = 2 sccm . The photoluminescence exhibited two peaks at around 1.7 eV and 2.2 - 2.3 eV. The first 1.7-eV-peak may be related to nanocrystallites in nc-Si films and the origin of another 2.2 - 2.3-eV-peak is not clear. Thus, hydrogen and fluorine appear to play different role in the crystallization process. In addition, under [ H 2] = 0 sccm , we found a close correlation among the increases in the ρ and the average grain size values and the SiH 2 density with increasing [ SiF 4/ He ].

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