Bandgap Engineering of Amorphous Hydrogenated Silicon Carbide

MRS Advances ◽  
2016 ◽  
Vol 1 (43) ◽  
pp. 2929-2934 ◽  
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.

Structural and morphological investigation of amorphous hydrogenated silicon carbide

2001 ◽  
Vol 34 (4) ◽  
pp. 465-472 ◽  
Author(s):  
R. J. Prado ◽  
M. C. A. Fantini ◽  
I. Pereyra ◽  
G. Y. Odo ◽  
C. M. Lepienski
Keyword(s):  
Silicon Carbide ◽  
Chemical Vapor ◽  
Infrared Spectrometry ◽  
Morphological Investigation ◽  
Hydrogenated Silicon ◽  
X Ray ◽  
Hydrogen Dilution ◽  
Amorphous Hydrogenated Silicon ◽  
Deposition Parameters ◽  
Transmission Electron

Amorphous hydrogenated silicon carbide thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) at temperatures ranging from 573 to 623 K, with different concentrations of silane and methane, exploring two deposition parameters: the radio frequency (r.f.) power and the hydrogen dilution. The aim of the work was to induce, predominantly, the formation of Si—C heteronuclear bonds in a homogeneous network. The composition was determined by Rutherford backscattering and the chemical bonding by Fourier transform infrared spectrometry. The local structural order was analyzed by means of extended X-ray absorption fine structure at the SiKedge. The morphology was investigated by small-angle X-ray scattering in order to determine the possible presence of voids in the amorphous matrix. The morphological investigation was completed by transmission electron microscopy. Better-structured films were obtained for a composition close to stoichiometry, grown with an r.f. power of 100 W and with 300 s.c.c.m. (standard cubic centimeter per minute) of hydrogen dilution.

Initial results and long-term clinical follow-up of an amorphous hydrogenated silicon-carbide-coated stent in daily practice

1998 ◽  
Vol 1 (2) ◽  
pp. 81-85
Author(s):  
Clara EE Hanekamp ◽  
Hans JRM Bonnier ◽  
Rolf H Michels ◽  
Kathinka H Peels ◽  
Eric PCM Heijmen ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Daily Practice ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Initial Results

DEPOSITION-AND-SUBSTRATE TUNABLE PHOTONIC BANDGAP IN OPTICAL RESPONSES OF HYDROGENATED AMORPHOUS SILICON CARBIDE THIN FILMS

2003 ◽  
Vol 17 (09) ◽  
pp. 387-392 ◽  
Author(s):  
NIKIFOR RAKOV ◽  
ARSHAD MAHMOOD ◽  
MUFEI XIAO
Keyword(s):  
Thin Films ◽  
Silicon Carbide ◽  
Photonic Bandgap ◽  
Visible Spectrum ◽  
Incoherent Light ◽  
Hydrogenated Silicon ◽  
Optical Responses ◽  
Amorphous Hydrogenated Silicon ◽  
The Status ◽  
Two Parameters

Amorphous hydrogenated silicon carbide (a-SiC:H) thin films have been prepared by the RF reactive magnetron sputtering technique. The optical properties of the films have been studied by optical spectroscopy with an incoherent light source. The material is commonly regarded as a dielectric. We have discovered however that some films that were prepared under certain deposition conditions and on certain substrates may respond to external light as a metallic thin film, i.e. there are strongly enhanced reflection peaks in the optical spectrum. We have further discovered that some films may have a strong and broadened absorption peak at about 590 nm, which is an apparent photonic bandgap in the visible spectrum. The appearance of the photonic bandgap is very sensitive to two parameters: the substrate and the deposition gas. By changing the two parameters, one shifts the status of the film from with and without the photonic bandgap.

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

Open Physics ◽  
2009 ◽  
Vol 7 (2) ◽  
Author(s):  
Jarmila Müllerová ◽  
Veronika Vavruňková ◽  
Pavel Å utta
Keyword(s):  
Chemical Vapour ◽  
Optical Transmittance ◽  
Band Gap Energy ◽  
Absorption Coefficients ◽  
Hydrogenated Silicon ◽  
Transmittance Spectra ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Ordering Effects ◽  
Amorphous Hydrogenated Silicon

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 (µc-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 cm−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.

Growth Mechanism and Chemical Structure of Amorphous Hydrogenated Silicon Carbide (a-SiC:H) Films Formed by Remote Hydrogen Microwave Plasma CVD From a Triethylsilane Precursor: Part 1

2009 ◽  
Vol 15 (1-3) ◽  
pp. 39-46 ◽  
Author(s):  
Aleksander M. Wrobel ◽  
Agnieszka Walkiewicz-Pietrzykowska ◽  
Marja Ahola ◽  
I. Juhani Vayrynen ◽  
Francisco J. Ferrer-Fernandez ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Growth Mechanism ◽  
Chemical Structure ◽  
Microwave Plasma ◽  
Plasma Cvd ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Microwave Plasma Cvd

scholarly journals On the Effect of Substrate Temperature on a-Si:H Deposition Using an Expanding Thermal Plasma

1996 ◽  
Vol 420 ◽  
Author(s):  
R. J. Severens ◽  
M. C. M. Van De Sanden ◽  
H. J. M. Verhoeven ◽  
J. Bastiaanssen ◽  
D. C. Schram
Keyword(s):  
Growth Rate ◽  
Substrate Temperature ◽  
Urbach Energy ◽  
Hydrogen Plasma ◽  
Hydrogen Abstraction ◽  
Plasma Jet ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Simple Kinetic Model ◽  
S Deposition

AbstractFast (7 nm/s) deposition of amorphous hydrogenated silicon with a midgap density of states less than 1016 cm-3 and an Urbach energy of 50 meV has been achieved using a remote argon/hydrogen plasma. The plasma is generated in a dc thermal arc (0.5 bar, 5 kW) and expands into a low pressure chamber (20 Pa) thus creating a plasma jet with a typical flow velocity of 103 m/s. Pure silane is injected into the jet immediately after the nozzle, in a typical flow mixture of Ar:H2:SiH4=55:10:10 scc/s. As the electron temperature in the recombining plasma is low (typ. 0.3 eV), silane radicals are thought to be produced mainly by hydrogen abstraction.Material quality in terms of refractive index, conductivity, microstructure parameter and optical bandgap was found to increase monotonously with substrate temperature, even up to 350 °C; for practically all low growth rate deposition schemes an optimum around 250 °C is observed. It will be argued that this behavior is consistent with a simple kinetic model involving physisorption and hopping, growth on dangling bonds and thermal desorption of hydrogen.

The effect of hydrogen dilution on the interatomic bonding of amorphous hydrogenated silicon: carbon

1994 ◽  
Vol 169 (1-2) ◽  
pp. 54-63 ◽  
Author(s):  
P.J.R. Honeybone ◽  
J.K. Walters ◽  
D.W. Huxley ◽  
R.J. Newport ◽  
W.S. Howells ◽  
...  
Keyword(s):  
Hydrogenated Silicon ◽  
Hydrogen Dilution ◽  
Amorphous Hydrogenated Silicon ◽  
Silicon Carbon ◽  
Interatomic Bonding

Efficient Visible Room Temperature Photoluminescence in Wide Gap Hydrogenated Amorphous Silicon-Carbon Alloys

1994 ◽  
Vol 336 ◽  
Author(s):  
Leandro R. Tessler ◽  
Ionel Solomon
Keyword(s):  
Room Temperature ◽  
Urbach Energy ◽  
Photoluminescence Intensity ◽  
Tetrahedral Coordination ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Silicon Carbon ◽  
Hydrogenated Amorphous ◽  
Carbon Concentrations ◽  
Phonon Model

ABSTRACTWe report a photoluminescence study on amorphous hydrogenated silicon carbon (a-Si1-xCx:H) alloys with carbon concentration in the range O < x < 0.5, prepared by PECVD in the “low-power” regime, that preserves the tetrahedral coordination of the carbon atoms. These samples have optical gaps higher than conventional “high power” alloys with the same carbon content. For carbon concentrations below x = 0.2 the photoluminescence behaves essentially as in pure a-Si:H with increased gap, Urbach energy and DOS. For higher carbon concentrations there is a change in the recombination process, that we attribute to a change in the dominating diffusion process of the photogenerated carriers. The integrated photoluminescence intensity for carbon-rich samples is very weakly dependent on the temperature, and at room temperature it approaches that of pure a-Si:H at 77K. For all samples, the photoluminescence bandwidth can be well described by a zero-phonon model.

Sign in / Sign up

Export Citation Format

Share Document