scholarly journals EXCITONS IN FUNCTION TO THE BINDING COEFICIENT IN MONOCRISTALLINE SILICON BASE.

2020 ◽  
Vol 9 (7) ◽  
pp. 80-86
Keyword(s):  
Space Charge ◽  
Crystal Lattice ◽  
Valence Band ◽  
Coupling Coefficient ◽  
Metal Contact ◽  
Rear Face ◽  
Polychromatic Light ◽  
Charge Zone ◽  
Very High ◽  
Minority Carriers

The exciton is a particle formed between one or more electrons intermediate levels with one or more holes in the valence band. These two particles are bonded by electrical interactions. These interactions are modeled by a coupling coefficient denoted b. Thus in this article, a study of the variation of the excess excitons density in the base in function to the binding coefficient was done. This study shows that, the excess excitons density is zero at the junction of the base and the space charge zone. By cons, in depth, the excitons density increases as a function to the coupling coefficient. Indeed, when one enters deep, interactions between holes and electrons become very important modeled by a high coupling coefficient. These result a reduction of the excess minority carriers mobility in the base and the formation of exciton complexes, hence the increase of the excess excitons density in the base. The reduction of the excess excitons density at the rear face is due to a very high excitons recombination in this region. This is due to a lack adhesion of the metal contact and disruption of the crystal lattice in this region. When the cell is under polychromatic light, the excess excitons density in the base is very high compared to that obtained when the cell is in dark.

Observation of multiple Bragg reflections accompanying forbidden Si(002) reflection in bent-perfect Si crystal

2021 ◽  
pp. 1-6
Author(s):  
P. Mikula ◽  
M. Vrána ◽  
J. Šaroun ◽  
V. Ryukhtin
Keyword(s):  
High Resolution ◽  
Crystal Lattice ◽  
Perfect Crystal ◽  
Monochromatic Beam ◽  
Very High

Strong multiple Bragg reflections (MBRs) which can be realized in a bent-perfect-crystal (BPC) slab provide a monochromatic beam of excellent resolution parameters. For identifying MBR effects in the BPC Si crystal, we used the method of azimuthal rotation of the crystal lattice around the scattering vector of the primary forbidden Si(200) reflection for a fixed chosen wavelength. In this paper, several azimuthal scans searching strong MBR effects with the intention of a possible practical exploitation for very high-resolution diffractometry are presented.

Thorium in crandallite-group minerals: an example from a Devonian bauxite deposit, Timan, Russia

2004 ◽  
Vol 68 (3) ◽  
pp. 489-497 ◽  
Author(s):  
L. E. Mordberg
Keyword(s):  
Crystal Lattice ◽  
Radiation Damage ◽  
Mineral Composition ◽  
Bauxite Deposit ◽  
Weathering Profile ◽  
Silicate Mineral ◽  
Fe Content ◽  
Very High ◽  
Type Substitution ◽  
Simplified Formula

AbstractA Th-rich mineral of the crandallite group has been investigated from the weathering profile of the Schugorsk bauxite deposit, Timan, Russia. It occurs within thin (up to 0.5 mm) organic-rich veinlets together with ‘leucoxene’ in the form of small shapeless grains which vary in size from 1—2 mm to 60—70 mm. Rare grains disseminated among boehmite crystals were also found. Microprobe analyses determined that the ThO2 content can be as high as 18 wt.%. The mineral composition is intermediate between crandallite CaAl3H(PO4)2(OH)6, goyazite SrAl3H(PO4)2(OH)6, Th-crandallite and svanbergite SrAl3PO4SO4(OH)6 in the beudantite group.Comparatively high contents of Fe and Si and a very high positive Th and Fe content correlation (r = +0.98) suggest that the formula of the hypothetical Th-bearing end-member is ThFe3(PO4,SiO4)2(OH)6 with Th and Si substituting for REE and Prespectively (woodhouseite-type substitution). Another possible substitution is Th4+ + Ca2+ ⇋ 2REE3+ (florencite-type). A deficiency of cations in the X site can be explained by either the presence of carbon, undetectable by microprobe, in the crystal lattice or a lack of X-site cations due to radiation damage induced by Th. Some excess of cations in the B site (Al and Fe3+) can be explained by the presence of very small boehmite and hematite inclusions on the crandallite grain surfaces. Th-rich crandallite may be the result of alteration of an unidentified silicate mineral from the parent rock with a composition close to the simplified formula Fe2+ThSiO4(OH)2.

scholarly journals New Coefficients of the Minority Carrier Lifetime and Bandgap Narrowing Models in the Transparent Emitter of Thin Film Silicon Solar Cells

2003 ◽  
Vol 26 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A. Zerga ◽  
M. Benosman ◽  
F. Dujardin ◽  
B. Benyoucef ◽  
J-P. Charles
Keyword(s):  
Silicon Solar Cell ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Bandgap Narrowing ◽  
Heavy Doping ◽  
High Level ◽  
Band Gap Narrowing ◽  
Very High ◽  
Minority Carriers ◽  
Good Agreement

In this study we have determined new coefficients for the physical model describing the band-gap narrowing and the minority carriers lifetime. This was accomplished according to the doping level of the thin emitter. This model allows us to take into account both the effects of the heavy doping and the majority carrier degeneration for the very high level of doping. The results we obtain by the corrected model are in good agreement with those reported in the literature and in different experiments. They show us the possibility of accurately evaluating the performances for then+psilicon solar cell. This model is then used to introduce a new concept for the thin layer emitter, called transparent emitter.

Characterization of Valence Band Offsets in P-SI/SIGE/SI by Space Charge Spectroscopy

1993 ◽  
Vol 326 ◽  
Author(s):  
K. Schmalz ◽  
H. RüCker ◽  
I. N. Yassievich ◽  
H. G. Grimmeiss ◽  
W. Mehr ◽  
...  
Keyword(s):  
Space Charge ◽  
Valence Band ◽  
Band Offsets

The Theory and Simulation of the Klystron RF Coupling Coefficient with the AC Space Charge Effects

2011 ◽  
Vol 33 (9) ◽  
pp. 2243-2247
Author(s):  
Chuan-lu Huang ◽  
Yao-gen Ding ◽  
Yong Wang ◽  
Ya-min Quan ◽  
Xing-juan Xie
Keyword(s):  
Space Charge ◽  
Coupling Coefficient ◽  
Space Charge Effects ◽  
Charge Effects

On the magnetic anisotropy and susceptibility of Fe(NH 4 SO 4 ) 2 , 6H 2 O

1961 ◽  
Vol 261 (1305) ◽  
pp. 207-214 ◽  
Keyword(s):  
Thermal Expansion ◽  
Magnetic Anisotropy ◽  
Crystal Lattice ◽  
Crystal Field ◽  
Coupling Coefficient ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Anisotropic Part ◽  
Free Ion

The theory of magnetic anisotropy and susceptibility of Fe 2+ in Tutton salts has been worked out on the basis of Abragam & Pryce’s method. It is found that the anisotropic part of the crystal field changes with temperature owing to the thermal expansion of the crystal lattice. The spin-orbit coupling coefficient has to be decreased by ~ 20 % from its free ion value of - 103 cm -1 which indicates some amount of overlap between the 3 d -Fe 2+ and 8 - and p -O 2- charge clouds. The agreement of the theoretical values with the experiment is good within the limitations of the approximations involved.

AC-Space-Charge Effects on Gap Coupling Coefficient of a Klystron Cavity

2012 ◽  
Vol 40 (3) ◽  
pp. 828-834
Author(s):  
Chuan-Lu Huang ◽  
Yao-Gen Ding ◽  
Wang Yong ◽  
Dong-Ping Gao
Keyword(s):  
Space Charge ◽  
Coupling Coefficient ◽  
Space Charge Effects ◽  
Charge Effects ◽  
Gap Coupling

Massenspektrometrische Untersuchungen an der Plasma-Grenzschicht / Mass Spectrometry at the Plasma Sheath

1974 ◽  
Vol 29 (9) ◽  
pp. 1276-1283
Author(s):  
Klaus Henrich ◽  
Karl Gerhard Müller
Keyword(s):  
Space Charge ◽  
Mass Spectrometer ◽  
Optical System ◽  
Mean Free Path ◽  
Plasma Sheath ◽  
Ion Current ◽  
Experimental Proof ◽  
Probe Current ◽  
Charge Zone ◽  
Ion Species

Mass spectrometric measurements of positive ions emerging from Ar-plasmas at 0.1-0.6 Torr are described. The adaption of the mass spectrometer requires besides the extraction probe an ion optical system, which causes the focussing and bunching of the ion current on the entrance of the time-of-flight mass spectrometer. Systematic measurements of the velocity distributions of the different ion species reveal:1. The Bohm-criterion is confirmed. In front of the wall the ions are heated in the quasineutral zone and are accelerated in the space charge zone, which here is in the order of magnitude of the ion mean free path.2. Heating and accelerating increase with growing ion current to the extraction probe.3. A further increase of the probe current causes collisions in the space charge zone which gives rise to a drop of the transmission of the optical system.4. The measurement of the current of one ion species as a function of the probe current is a simple experimental proof for collisions of the ions in the space charge zone.

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