Light-induced hydrogen evolution from hydrogenated amorphous silicon: Hydrogen diffusion by formation of bond centered hydrogen

2014 ◽  
Vol 115 (7) ◽  
pp. 073503 ◽  
Author(s):  
H. Tanimoto ◽  
H. Arai ◽  
H. Mizubayashi ◽  
M. Yamanaka ◽  
I. Sakata
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Evolution ◽  
Hydrogen Diffusion ◽  
Hydrogenated Amorphous Silicon ◽  
Hydrogenated Amorphous

Role of Hydrogen Microstructure in Amorphous Silicon

1992 ◽  
Vol 258 ◽  
Author(s):  
Sufi Zafar ◽  
E. A. Schiff
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Evolution ◽  
Hydrogen Diffusion ◽  
Hydrogenated Amorphous Silicon ◽  
Hydrogenated Amorphous ◽  
Unified Description

ABSTRACTA model for correlating the observed properties of hydrogenated amorphous silicon (a-Si:H) with the underlying hydrogen microstructure is reviewed. The model provides a unified description of defect equilibration, hydrogen evolution, rehydrogenation and hydrogen diffusion measurements.

Transient Mean-Field Reaction-Diffusion Model Applied to Hydrogen Evolution From Hydrogenated Amorphous Silicon

1995 ◽  
Vol 377 ◽  
Author(s):  
A. J. Franzi ◽  
M. Mavrikakis ◽  
J. W. Schwank ◽  
J. L. Gland
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Evolution ◽  
Diffusion Model ◽  
Mean Field ◽  
Hydrogenated Amorphous Silicon ◽  
Reaction Diffusion ◽  
Reaction Diffusion Model ◽  
Wide Range ◽  
Field Reaction ◽  
Hydrogenated Amorphous

ABSTRACTHydrogen bulk mobility plays an important role in determining a wide range of materials and electronic properties of hydrogenated amorphous silicon (a-Si:H). The existence of two types of hydrogen traps plays an important role in controlling hydrogen mobility in, and evolution of hydrogen from a-Si:H, however, theoretical and experimental literature values for the trap energetics vary considerably. We have developed a mean-field reaction-diffusion model which explicitly includes two trap states and realistic surface processes to model hydrogen evolution from a-Si:H. Modern numerical techniques were required to solve this challenging problem over the wide range of temperatures and concentrations encountered in typical hydrogen evolution experiments. The model is based on a number of experimentally established parameters. Comparison of our rigorous model with temperature programmed hydrogen evolution experiments provides a powerful method for characterizing the energetics, trap concentrations and diffusivity of hydrogen in a-Si:H.

Separation of Nucleation and Growth Processes of Nanocrystalline Silicon by Hydrogen Radical Treatment of Hydrogenated Amorphous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
Masanori Otobe ◽  
Shunri Oda
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Diffusion ◽  
Hydrogenated Amorphous Silicon ◽  
Nanocrystalline Silicon ◽  
Nucleation And Growth ◽  
Growth Processes ◽  
Plan View ◽  
Hydrogen Radical ◽  
Hydrogen Radicals ◽  
Hydrogenated Amorphous

ABSTRACTWe have investigated nucleation and growth mechanism of nanocrystalline silicon (nc-Si) based on the experimental observation of plan-view transmission electron microscopy. Nanocrystalline Si has been prepared by hydrogen radical annealing of hydrogenated amorphous silicon (a-Si:H) layer, which is deposited on hydrogen radical treated a-Si:H buffer layer. Nanocrystallization depends critically upon hydrogen radical annealing time and the thickness ofa-Si:H layer. Hydrogen radicals play important roles in both nucleation and growth processes in a different way. Growth of nc-Si can be explained by “hydrogen diffusion model”, in which hydrogen radicals diffusing through a-Si:H layer to interface cause nanocrystallization. Our results imply that nuclei for nc-Si are generated at the interface between a-Si:H and under layer when treated by hydrogen radicals.

Kinetics Of Hydrogen Evolution And Crystallization In Hydrogenated Amorphous Silicon Films Studied By Thermal Analysis And Raman Scattering

1993 ◽  
Vol 321 ◽  
Author(s):  
Nagarajan Sridhar ◽  
D. D. L. Chung ◽  
W. A. Anderson ◽  
W. Y. Yu ◽  
L. P. Fu ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Raman Scattering ◽  
Amorphous Silicon ◽  
Hydrogen Evolution ◽  
Deposition Temperature ◽  
Evolved Gas Analysis ◽  
Silicon Film ◽  
Hydrogenated Amorphous Silicon ◽  
Film Deposition ◽  
Hydrogenated Amorphous

ABSTRACTWe observed the processes of hydrogen evolution and crystallization in hydrogenated Amorphous silicon 0.5–7 μm thick films (deposited by dc glow discharge on Molybdenum) by differential scanning calorimetry (DSC), Raman scattering and thermogravimetric analysis (TGA). Investigation was made as a function of doping, deposition temperature and film thickness. For all the films, an endothermic DSC peak was observed at 694 °C (onset). That this peak was at least partly due to hydrogen evolution was shown by TGA, which showed weight loss beginning at 694 °C, and by evolved gas analysis, which showed hydrogen evolution at 694 °C. This temperature (658–704 °C) increased with increasing heating rate (5–30 °C/min). Doping reduced this temperature from 694 to 625 °C for boron doping and to 675 °C for phosphorous doping. Hydrogen evolution kinetics and FTIR results suggest that the silicon-hydrogen bonding in the intrinsic film was a mixture of SiH and S1H2, and was predominantly SiH in the phosphorous doped films and SiH2 in the boron doped films. Crystallization was independent of silicon-hydrogen bonding in the as-deposited Amorphous silicon film. It was bulk (not interface) induced. No exothermic DSC peak accompanied the crystallization. The film deposition temperature had little effect on the DSC result, but crystallization was enhanced by a higher deposition temperature.

Hydrogen Diffusion in Boron-Doped Hydrogenated Amorphous Silicon Films: Crystallization and Induced Structural Changes

2005 ◽  
Vol 864 ◽  
Author(s):  
F. Kail ◽  
A. Hadjadj ◽  
P. Roca i Cabarrocas
Keyword(s):  
Amorphous Silicon ◽  
Structural Changes ◽  
Hydrogen Diffusion ◽  
Hydrogen Plasma ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Films ◽  
Hydrogen Atoms ◽  
Boron Doped ◽  
Hydrogenated Amorphous ◽  
Positively Charged

AbstractWe have studied the evolution of the structure of boron-doped hydrogenated amorphous silicon films exposed to a hydrogen plasma. From the early stages of exposure, hydrogen diffuses and forms a thick H-rich subsurface. At longer times, hydrogen plasma leads to the formation of a microcrystalline layer via chemical transport without crystallization of the initial layer. We observe that the hydrogen content increases in the films during a plasma exposure and once the microcrystalline layer is formed hydrogen diffuses out of the sample accompanied with a decrease in the boron content. This effect can be attributed to the electric field developed within the heterojunction a-Si:H/μc-Si:H that drives the positively charged hydrogen atoms in the boron-doped layer towards the μc-Si:H layer.

Enhanced Hydrogen Diffusion Under Illumination in Hydrogenated Amorphous Silicon

1992 ◽  
Vol 258 ◽  
Author(s):  
P.V. Santos ◽  
N.M. Johnson ◽  
R.A. Street
Keyword(s):  
Diffusion Coefficient ◽  
Electric Field ◽  
Experimental Evidence ◽  
Amorphous Silicon ◽  
Hydrogen Diffusion ◽  
Hydrogenated Amorphous Silicon ◽  
Diffusion Region ◽  
Hydrogen Diffusion Coefficient ◽  
Hydrogenated Amorphous ◽  
Carrier Population

ABSTRACTWe provide experimental evidence for the fact that hydrogen diffusion in hydroge-nated amorphous silicon is controlled by the concentration of electronic carriers. It is experimentally demonstrated that the hydrogen diffusion coefficient (a) is enhanced if the carrier population is increased by illumination and (b) is strongly suppressed if carriers are extracted from the diffusion region by the application of an electric field.

Photoelectrochemical water splitting by tandem type and heterojunction amorphous silicon electrodes

1988 ◽  
Vol 66 (8) ◽  
pp. 1853-1856 ◽  
Author(s):  
Yuichi Sakai ◽  
Satoshi Sugahara ◽  
Michio Matsumura ◽  
Yoshihiro Nakato ◽  
Hiroshi Tsubomura
Keyword(s):  
Sulfuric Acid ◽  
Amorphous Silicon ◽  
Hydrogen Evolution ◽  
Water Splitting ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Conversion ◽  
External Bias ◽  
P Type ◽  
Conversion Efficiencies ◽  
Hydrogenated Amorphous

The tandem type hydrogenated amorphous silicon (a-Si) electrode having an [n–i–p–n–i–p] structure and a similar tandem a-Si electrode having [n–i–p–n–i–p–n] layers deposited on p-type crystalline Si showed cathodic photocurrents accompanied by hydrogen evolution starting at potentials 1.67 and 2.08 V, respectively, more positive than the thermodynamic hydrogen evolution potential in a sulfuric acid solution. These electrodes, when connected to an RuO2 counterelectrode, caused sustained water splitting without external bias, giving solar-to-chemical conversion efficiencies of 1.98% and 2.93%, respectively, under simulated AM 1, 100 mW cm−2 solar radiation. These efficiencies are critically compared with the efficiency of another type of solar photoelectrolysis of water, namely, the electrolysis of water by the electrical output from solid-state solar cells.

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