Concentration Dependence of Hydrogen Diffusion in Hydrogenated Silicon

1998 ◽  
Vol 507 ◽  
Author(s):  
W. Beyer ◽  
U. Zastrow
Keyword(s):  
Diffusion Coefficient ◽  
Amorphous Silicon ◽  
Concentration Dependence ◽  
Hydrogen Concentration ◽  
Hydrogen Diffusion ◽  
Band Model ◽  
Hydrogenated Silicon ◽  
Trapping Model ◽  
Hydrogen Implantation ◽  
Amorphous Si

ABSTRACTThe concentration dependence of hydrogen diffusion was studied in hydrogenated crystalline and amorphous silicon prepared by hydrogen implantation into crystalline Si wafers and into amorphous silicon of low hydrogen concentration. The results are compared with data for plasma-grown a-Si:H and µc-Si:H films. The increase of the diffusion coefficient with rising hydrogen concentration in a-Si:H is explained by an (equilibrium) energy band model of hydrogen diffusion whereas the decrease of the diffusion coefficient in c-Si:H is explained by a trapping model. The different behavior is attributed to a greater flexibility of the amorphous Si network compared to the crystalline Si lattice which is also visible in a difference in hydrogen-related microstructure formation.

Dependence of H Diffusion in Hydrogenated Silicon on Doping and the Fermi Level

2000 ◽  
Vol 609 ◽  
Author(s):  
Wolfhard Beyer ◽  
Uwe Zastrow
Keyword(s):  
Hydrogen Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Depth Profiling ◽  
Neutral Hydrogen ◽  
Diffusion Path ◽  
Strong Increase ◽  
Band Model ◽  
Hydrogenated Silicon ◽  
As Doping ◽  
Hydrogen Implantation

ABSTRACTFor three types of hydrogenated silicon films, amorphous, microcrystalline and crystalline hydrogenated silicon, hydrogen diffusion was studied as a function of doping level employing depth profiling by secondary ion mass spectrometry. Hydrogen implantation was used to control the hydrogen concentration. All three materials show a similar doping dependence of H diffusion, namely a strong increase upon boron (p-type) doping and a much lesser increase for n- type (P, As) doping. In a band model of H diffusion, the effect is related to a decrease in energy of the hydrogen diffusion path. Possible explanations are a different charge state of diffusing hydrogen or an effect of the Fermi energy on the release energy of neutral hydrogen.

Diffusion of Hydrogen in Titanium-Vanadium Alloys

2005 ◽  
Vol 237-240 ◽  
pp. 340-345 ◽  
Author(s):  
Hans Jürgen Christ ◽  
S. Schroers ◽  
F.H.S. dos Santos
Keyword(s):  
Diffusion Coefficient ◽  
Titanium Alloys ◽  
Hydrogen Concentration ◽  
Hydrogen Diffusion ◽  
High Strength ◽  
Vanadium Concentration ◽  
Vanadium Alloys ◽  
High Hydrogen ◽  
Hydrogen Diffusion Coefficient ◽  
Diffusion Of Hydrogen

β–titanium alloys are very attractive materials for many applications because they combine low density, high strength and excellent corrosion resistance. The available data indicate a much higher hydrogen diffusion coefficient in β–titanium alloys as compared to α and α + β alloys. In order to predict the range of applicability of β–titanium alloys in environments, which release hydrogen, the hydrogen diffusion coefficient (DH) needs to be known quantitatively. In the framework of this study the value of DH was determinated on samples, which were electrochemically hydrogen charged. Long thin rods were used as samples and charged in such a way that high hydrogen concentrations were obtained in one half of the length of the specimens, while the other half was kept virtually unaffected. After charging, the rods were annealed enabling hydrogen to diffuse. Hydrogen concentration profiles were experimentally determined and evaluated on the basis of the Matano technique, in order to reveal any effect of concentration on DH. The experiments were carried out on β–titanium alloys of the binary Ti–V system. The concentration range of vanadium in the alloys studied was selected in such a way that it represents the compositions commonly found in commercial alloys. The results show that the effect of hydrogen concentration on DH is negligible and that DH increases with the vanadium concentration.

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.

Hydrogen Diffusion in the Hydrogen Collision Model of Amorphous Silicon Metastability

1999 ◽  
Vol 557 ◽  
Author(s):  
Howard M. Branz
Keyword(s):  
Diffusion Coefficient ◽  
Amorphous Silicon ◽  
Hydrogen Diffusion ◽  
Exchange Reactions ◽  
Collision Model ◽  
Long Time ◽  
Insight Into

AbstractThe trap-controlled model of H diffusion that underpins the H collision model of amorphous silicon metastability provides new insight into thermal and light-enhanced H diffusion in a-Si:H. The longstanding puzzle of the linear DB-dependence of diffusion coefficient with doping is resolved. Expressions for the light-induced H diffusion coefficient are derived with and without D-for-H exchange reactions. It is shown that D-for-H exchange does not affect the long-time diffusion coefficient that is measured under illumination.

Diffusion coefficient using pausing time of hydrogen in a-Si:H with exponential energy distribution

2015 ◽  
Vol 29 (14) ◽  
pp. 1550083 ◽  
Author(s):  
Harumi Hikita ◽  
Kazuo Morigaki
Keyword(s):  
Distribution Function ◽  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Energy Distribution ◽  
Amorphous Silicon ◽  
Hydrogen Diffusion ◽  
Hydrogenated Amorphous Silicon ◽  
Diffusion Time ◽  
Energy Distribution Function ◽  
Hydrogenated Amorphous

The diffusion coefficient of hydrogen is obtained for exponential energy distribution in hydrogenated amorphous silicon (a-Si:H). It is shown that the diffusion coefficient follows the form of τα-1 (τ: diffusion time) in the case of α < 1 and a larger τ, in which α is the ratio of hydrogen temperature to width for energy distribution function. In the case of α ≥ 1, as α reaches infinity at the limit, the hydrogen diffusion approaches Brownian motion.

The Concentration Dependence of Hydrogen Diffusion in fcc TiHx, TiDxand YHx*

1992 ◽  
Vol 1 (1) ◽  
pp. 631-635
Author(s):  
U. Stuhr ◽  
D. Steinbinder ◽  
H. Wipf ◽  
B. Frick
Keyword(s):  
Concentration Dependence ◽  
Hydrogen Diffusion
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