Optical absorption in PECVD deposited thin hydrogenated silicon in light of ordering effects

AbstractWe report results obtained from measurements of optical transmittance spectra carried out on a series of silicon thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane diluted with hydrogen. Hydrogen dilution of silane results in an inhomogeneous growth during which the material evolves from amorphous hydrogenated silicon (a-Si:H) to microcrystalline hydrogenated silicon (Âµc-Si:H). Spectral refractive indices and absorption coefficients were determined from transmittance spectra. The spectral absorption coefficients were used to determine the Tauc optical band gap energy, the B factor of the Tauc plots, E 04 (energy at which the absorption coefficient is equal to 104 cmâˆ’1), and the Urbach energy as a function of the hydrogen dilution. The results were correlated with microstructure, namely volume fractions of the amorphous and crystalline phase with voids, and with the grain size.

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Microstructure of Thin Film Photoconductors and its Correlation with Optical and Electronic Properthss

MRS Proceedings ◽

10.1557/proc-452-925 ◽

1996 ◽

Vol 452 ◽

Author(s):

U. Klement ◽

D. Horst ◽

F. Ernst

Keyword(s):

Thin Film ◽

Electron Microscopy ◽

Thin Films ◽

Transmission Electron Microscopy ◽

Vapour Deposition ◽

Chemical Vapour ◽

Hydrogenated Silicon ◽

Amorphous Hydrogenated Silicon ◽

Transmission Electron ◽

Electronic Eye

AbstractThe objective of this work is to find a material to replace amorphous hydrogenated silicon used as photosensitive part in the “retina” of an “electronic eye”. For that reason, ZnS, ZnSe, CdS and CdSe were chosen for investigations. Thin films, prepared by chemical vapour deposition, were characterized by transmission electron microscopy. The observed microstructures were correlated with the optoelectronic properties of these materials. CdSe was found to be the most promising material for our application. Hence, the influence of a dielectric interlayer and the effects of additional annealing treatments were analyzed for CdSe and will be discussed with respect to the optimization of the material.

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Stoichiometric amorphous hydrogenated silicon carbide thin film synthesis using DC-saddle plasma enhanced chemical vapour deposition

2013 IEEE 5th International Nanoelectronics Conference (INEC) ◽

10.1109/inec.2013.6465984 ◽

2013 ◽

Author(s):

Behzad Jazizadeh Karimi ◽

Ali B. Alamin Dow ◽

Nazir P. Kherani

Keyword(s):

Thin Film ◽

Silicon Carbide ◽

Chemical Vapour Deposition ◽

Vapour Deposition ◽

Chemical Vapour ◽

Hydrogenated Silicon ◽

Amorphous Hydrogenated Silicon ◽

Film Synthesis

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A study of optical absorption in amorphous hydrogenated silicon thin films of varied thickness

Applied Surface Science ◽

10.1016/j.apsusc.2010.03.022 ◽

2010 ◽

Vol 256 (18) ◽

pp. 5667-5671 ◽

Cited By ~ 31

Author(s):

J. Müllerová ◽

L. Prušáková ◽

M. Netrvalová ◽

V. Vavruňková ◽

P. Šutta

Keyword(s):

Thin Films ◽

Optical Absorption ◽

Hydrogenated Silicon ◽

Silicon Thin Films ◽

Amorphous Hydrogenated Silicon

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Influence of deposition temperature on amorphous structure of PECVD deposited a-Si:H thin films

Open Physics ◽

10.2478/s11534-011-0041-4 ◽

2011 ◽

Vol 9 (5) ◽

Cited By ~ 2

Author(s):

Jarmila Müllerová ◽

Marinus Fischer ◽

Marie Netrvalová ◽

Miro Zeman ◽

Pavel Šutta

Keyword(s):

Thin Films ◽

Deposition Temperature ◽

Chemical Vapour ◽

Visible Region ◽

Amorphous Structure ◽

Band Gap Energy ◽

Silicon Hydride ◽

Tauc Plot ◽

Amorphous Hydrogenated Silicon ◽

Amorphous Network

AbstractThe effect of deposition temperature on the structural and optical properties of amorphous hydrogenated silicon (a-Si:H) thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane diluted with hydrogen was under study. The series of thin films deposited at the deposition temperatures of 50–200°C were inspected by XRD, Raman spectroscopy and UV Vis spectrophotometry. All samples were found to be amorphous with no presence of the crystalline phase. Ordered silicon hydride regions were proved by XRD. Raman measurement analysis substantiated the results received from XRD showing that with increasing deposition temperature silicon-silicon bond-angle fluctuation decreases. The optical characterization based on transmittance spectra in the visible region presented that the refractive index exhibits upward trend with increasing deposition temperature, which can be caused by the densification of the amorphous network. We found out that the scale factor of the Tauc plot increases with the deposition temperature. This behaviour can be attributed to the increasing ordering of silicon hydride regions. The Tauc band gap energy, the iso-absorption value their difference were not particularly influenced by the deposition temperature. Improvements of the microstructure of the Si amorphous network have been deduced from the analysis.

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ChemInform Abstract: UHV Study of Hydrogen Atom Induced Etching of Amorphous Hydrogenated Silicon Thin Films.

ChemInform ◽

10.1002/chin.200139255 ◽

2010 ◽

Vol 32 (39) ◽

pp. no-no

Author(s):

Thomas Zecho ◽

Birgit D. Brandner ◽

Juergen Biener ◽

Juergen Kueppers

Keyword(s):

Thin Films ◽

Hydrogen Atom ◽

Hydrogenated Silicon ◽

Silicon Thin Films ◽

Amorphous Hydrogenated Silicon

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Fast Deposition of Polycrystalline Silicon Films by Hot-Wire CVD

MRS Proceedings ◽

10.1557/proc-377-119 ◽

1995 ◽

Vol 377 ◽

Cited By ~ 28

Author(s):

A. R. Middya ◽

A. Lloret ◽

J. Perrin ◽

J. Huc ◽

J. L. Moncel ◽

...

Keyword(s):

Electron Microscopy ◽

Polycrystalline Silicon ◽

Vapour Deposition ◽

Chemical Vapour ◽

Hot Wire ◽

Crystalline Orientation ◽

Silicon Thin Films ◽

Hydrogen Dilution ◽

Si Films ◽

Polycrystalline Silicon Films

ABSTRACTPolycrystalline silicon thin films have been deposited at fast growth rates (50 Å/s) by hotwire chemical vapour deposition (HW-CVD) from SiH4/H2 gas mixtures at low substrate temperature (400–500°C). The surface morphology of these films consists of 0.5 – 2.0μm dendritic grains as seen by electron microscopy. The films have a columnar morphology with grains starting from the substrate either on glass or c-Si. Even the 150 nm thick initial layer is polycrystalline. The preferential crystalline orientation of the poly-Si film is apparently not governed by the radiative source but strongly depends on the type and orientation of the substrate. A strong hydrogen dilution (>90%) of silane is essential to obtain poly-Si films with optimal crystalline structure.

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Chemical vapour deposition of amorphous hydrogenated silicon with a CO2 laser: chemical mechanism

Thin Solid Films ◽

10.1016/0040-6090(92)90900-v ◽

1992 ◽

Vol 218 (1-2) ◽

pp. 29-39 ◽

Cited By ~ 10

Author(s):

K Hesch ◽

H Karstens ◽

P Hess

Keyword(s):

Chemical Vapour Deposition ◽

Co2 Laser ◽

Vapour Deposition ◽

Chemical Vapour ◽

Chemical Mechanism ◽

Hydrogenated Silicon ◽

Amorphous Hydrogenated Silicon

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Bandgap Engineering of Amorphous Hydrogenated Silicon Carbide

MRS Advances ◽

10.1557/adv.2016.422 ◽

2016 ◽

Vol 1 (43) ◽

pp. 2929-2934 ◽

Cited By ~ 1

Author(s):

J. A. Guerra ◽

L. M. Montañez ◽

K. Tucto ◽

J. Angulo ◽

J. A. Töfflinger ◽

...

Keyword(s):

Silicon Carbide ◽

Urbach Energy ◽

Amorphous Material ◽

Deposition Process ◽

Bandgap Energy ◽

Bandgap Engineering ◽

Hydrogenated Silicon ◽

Hydrogen Dilution ◽

Amorphous Hydrogenated Silicon ◽

Proposed Model

ABSTRACTA simple model to describe the fundamental absorption of amorphous hydrogenated silicon carbide thin films based on band fluctuations is presented. It provides a general equation describing both the Urbach and Tauc regions in the absorption spectrum. In principle, our model is applicable to any amorphous material and it allows the determination of the bandgap. Here we focus on the bandgap engineering of amorphous hydrogenated silicon carbide layers. Emphasis is given on the role of hydrogen dilution during the deposition process and post deposition annealing treatments. Using the conventional Urbach and Tauc equations, it was found that an increase/decrease of the Urbach energy produces a shrink/enhancement of the Tauc-gap. On the contrary, the here proposed model provides a bandgap energy which behaves independently of the Urbach energy.

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Hydrogenated Silicon Films Prepared by Remote Plasma CVD

MRS Proceedings ◽

10.1557/proc-192-577 ◽

1990 ◽

Vol 192 ◽

Author(s):

Sung Chul Kim ◽

Seung Kyu Lee ◽

Sung Mo Soe ◽

Sung Ok Koh ◽

Sung Shil Ihm ◽

...

Keyword(s):

Chemical Vapour ◽

Substrate Bias ◽

Rf Power ◽

Remote Plasma ◽

Substrate Bias Voltage ◽

Hydrogenated Silicon ◽

Gas Concentration ◽

Hydrogen Dilution ◽

Plasma Chemical Vapour Deposition

ABSTRACTWe have studied the improvement of the quality of undoped a-Si:H deposited by remote-plasma chemical vapour deposition. The effects of reactant gas concentration, rf power, substrate bias voltage on the electrical and optical properties have been investigated. Some hydrogen dilution of si lane improves the photoeletric property and a high rf power gives rise to the defect creation due to the ion bombardment on the growing surface. The positive substrate bias improves the quality of undoped a-Si:H.

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