602 research outputs found
In situ formation of indium catalysts to synthesize crystalline silicon nanowires on flexible stainless steel substrates by PECVD
No full textThe p recombination layer in tunnel junctions for micromorph tandem solar cells
No full textA new tunnel recombination junction is fabricated for n-i-p type micromorph tandem solar cells. We insert a thin heavily doped hydrogenated amorphous silicon (a-Si:H) p(+) recombination layer between the n a-Si:H and the p hydrogenated nanocrystalline silicon (nc-Si:H) layers to improve the performance of the n-i-p tandem solar cells. The effects of the boron doping gas ratio and the deposition time of the p-a-Si: H recombination layer on the tunnel recombination junctions have been investigated. The current-voltage characteristic of the tunnel recombination junction shows a nearly ohmic characteristic, and the resistance of the tunnel recombination junction can be as low as 1.5 Omega.cm(2) by using the optimized p-a-Si:H recombination layer. We obtain tandem solar cells with open circuit voltage V(oc) = 1.4 V, which is nearly the sum of the V(oc)s of the two corresponding single cells, indicating no V(oc) losses at the tunnel recombination junction
Optical properties of boron-doped Si nanowires
No full textRaman scattering and photoluminescence (PL) of boron-doped silicon nanowires have been investigated. Raman spectra showed a band at 480 cm(-1), indicating that the crystallinity of the nanowires was suppressed by boron doping. PL taken from B-doped SiNWS at room temperature exhibited three distinct emission peaks at 1.34, 1.42. and 1.47 eV and the PL intensity was much stronger than that of undoped SiNWS. The increased PL intensity should be very profitable for nano-optoelectronics. (C) 2004 Elsevier B.V. All rights reserved
Width of the exotic Xb (5568) state through its strong decay to Bs0 π+
No full textAzizi, Kazem (Dogus Author)The width of the newly observed exotic state Xb(5568) is calculated via its dominant strong decay to Bs0π+ using the QCD sum rule method on the light cone in conjunction with the soft-meson approximation. To this end, the vertex XbBsπ is studied and the strong coupling gXbBsπ is computed employing for Xb(5568) state the interpolating diquark-antidiquark current of the [su][bd] type. The obtained prediction for the decay width of Xb(5568) is confronted and a nice agreement found with the experimental data of the
Boron-doped silicon nanowires grown by plasma-enhanced chemical vapor deposition
No full textBoron-doped ( B-doped) silicon nanowires have been successfully synthesized by plasma-enhanced chemical vapor deposition (PECVD) at 440degreesC using silane as the Si source, diborane( B2H6) as the dopant gas and An as the catalyst. It is desirable to extend this technique to the growth of silicon nanowire pn junctions because PECVD enables immense chemical reactivity
Silicon nanowires grown on a pre-annealed Si substrate
No full textPolycrystalline Si nanowires (poly SiNWS) were successfully synthesized by plasma-enhanced chemical vapor deposition (PECVD) at 440degreesC using silane as the Si source and Au as the catalyst. The diameters of Si nanowires range from 15 to 100nm. The growth process indicates that to fabricate SiNWS by PECVD, pre-annealing at high temperature is necessary. A few interesting nanowires with Au nanoclusters uniformly distributed in the body of the wire were also produced by this technique. (C) 2002 Elsevier Science B.V. All rights reserved
STUDY OF MICROSTRUCTURE AND DEFECTS IN HYDROGENATED MICROCRYSTALLINE SILICON FILMS
No full textMicrocrystalline silicon films were deposited by very high frequency (VHF) plasma-enhanced chemical vapor deposition (PECVD) with different hydrogen dilution. The microstructure of these films was investigated using Raman spectroscopy and infrared absorption (IR) spectra. The crystalline, amorphous, and grain boundary volume fractions X-c, X-a and X-gb were estimated from Raman measurements. An interface structure factor (R-if) is proposed to characterize the grain boundary volume fractions in IR spectroscopy. The density of states (DOS) of the microcrystalline crystalline silicon films were studied by phase-shift analysis of modulated photocurrent (MPC) and photoconductivity spectroscopy. It was observed that DOS increases with increasing grain boundary volume fractions, while the values of electron mobility-lifetime product mu T-e(e) disease
New geometric formalism for gravity equation in empty space
No full textIn this paper, a complex daor field which can be regarded as the square root of space-time metric is proposed to represent gravity. The locally complexified geometry is set up, and the complex spin connection constructs a bridge between gravity and SU(1, 3) gauge field. Daor field equations in empty space are acquired, which are one-order differential equations and do not conflict with Einstein's gravity theory.Astronomy & AstrophysicsSCI(E)1ARTICLE61009-10221
Quadrupole pairing and downturn of moment of inertia for the superdeformed band Hg-194(1)
No full textThe omega variation of moments of inertia of superdeformed bands is investigated by a particle-number conserving (PNC) method of the cranked shell model Hamiltonian with monopole and quadrupole pairings. The observed omega dependence of the moments of inertia for Hg-192,Hg-194(1), particularly the shift in J((2)) downturn for Hg-194(1) to a higher frequency, are well reproduced by the PNC calculation. The microscopic mechanism of the omega dependence of J((2)) (contribution to J((2)) from each cranked Nilsson orbital) is clearly exhibited in the PNC calculation. The shift of the J((2)) downturn for Hg-194(1) is mainly attributed to the protons in the N = 6 intruder orbitals under the influence of Q(20) quadrupole pairing.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000165744400057&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, NuclearSCI(E)24ARTICLE6null6
Computer simulation of a-Si : H/mu c-Si : H diphasic silicon solar cells
No full textBased on our experimental research on diphasic silicon films, the parameters such as absorption coefficient, mobility lifetime product and bandgap were estimated by means of effective-medium theory. And then computer simulation of a-Si: H/mu c-Si: H diphasic thin film solar cells was performed. It was shown that the more crystalline fraction in the diphasic silicon films, the higher short circuit density, the lower open-circuit voltage and the lower efficiency. From the spectral response, we can see that the response in long wave region was improved significantly with increasing crystalline fraction in the silicon films. Taking Lambertian back refraction into account, the diphasic silicon films with 40%-50% crystalline fraction was considered to be the best intrinsic layer for the bottom solar cell in micromorph tandem
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