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1.
《Comptes Rendus Physique》2004,5(3):297-304
We studied the macroscopic effects of nuclear magnetization. Highly polarized xenon is often used to increase the sensitivity in NMR investigations of porous media, diluted liquids or for imaging in the gas phase. In the condensed phase, however, highly nuclear spin polarized xenon also possesses a sizable magnetization due to the nuclear spin density. This results in an additional magnetic field, that is used to measure the polarization of the sample, when only the particle density is known. Here we find Pz≈0.8 corresponding to a spin temperature of 0.5 mK. We use isotopically enriched xenon with a 129Xe abundance of 0.71. At high abundance of 129Xe and high nuclear polarization the dipolar linewidth is considerably reduced. We find for small angle excitation a reduction from 650 Hz to 400 Hz. We investigate this using a thin film geometry. The susceptibility effects of the substrate and the Xe film are treated. The macroscopic angle between the normal of the film and the external field strongly changes the polarization induced line shift and line width. The first follows an expected cos2θ dependence with an understood amplitude the latter however is not understood up to now. Relaxation of 129Xe in the condensed film is observed to be T1=15±1.8 min, much faster than expected. To cite this article: P. Gerhard et al., C. R. Physique 5 (2004). 相似文献
2.
Xin Zhang Xuezhao Shi Weichun Ye Chuanli Ma Chunming Wang 《Applied Physics A: Materials Science & Processing》2009,94(2):381-386
Quaternary compound semiconductor Cu2ZnSnS4 (CZTS), which appears to be a promising candidate for the absorber of a thin film type solar cell, was grown on polycrystalline
Ag substrates by electrochemical epitaxial method. The elements were deposited in the following sequence: S/Sn/S/Cu/S/Zn/S/Cu… ,
the order being one cycle of SnS, one cycle of ZnS and two cycles of CuS. Morphology of the deposit has been characterized
by field emission scanning electron microscopy (FE-SEM) with an energy dispersive X-ray (EDX) analyzer. X-ray diffraction
(XRD) studies showed a (112) preferred orientation for the deposit. X-ray photoelectron spectroscopy (XPS) of the deposit
indicated an approximate ratio 2:1:1:4 of Cu, Zn, Sn, and S, the expected stoichiometry for the deposit, and similar results
have been obtained from EDX data. Near IR absorption measurements of the deposit at room temperature indicated a direct band
gap of 1.5 eV, and open-circuit potential (OCP) studies indicated a good p-type property, both of which were suitable for
fabricating a thin film solar cell. 相似文献
3.
J. O. González S. Shaji D. Avellaneda G. A. Castillo T. K. Das Roy B. Krishnan 《Applied Physics A: Materials Science & Processing》2014,116(4):2095-2105
Photovoltaic structures were prepared using AgSb(S x Se1?x )2 as absorber and CdS as window layer at various conditions via a hybrid technique of chemical bath deposition and thermal evaporation followed by heat treatments. Silver antimony sulfo selenide thin films [AgSb(S x Se1?x )2] were prepared by heating multilayers of sequentially deposited Sb2S3/Ag dipped in Na2SeSO3 solution, glass/Sb2S3/Ag/Se. For this, Sb2S3 thin films were deposited from a chemical bath containing SbCl3 and Na2S2O3. Then, Ag thin films were thermally evaporated on glass/Sb2S3, followed by selenization by dipping in an acidic solution of Na2SeSO3. The duration of dipping was varied as 3, 4 and 5 h. Two different heat treatments, one at 350 °C for 20 min in vacuum followed by a post-heat treatment at 325 °C for 2 h in Ar, and the other at 350 °C for 1 h in Ar, were applied to the multilayers of different configurations. X-ray diffraction results showed the formation of AgSb(S x Se1?x )2 thin films as the primary phase and AgSb(S,Se)2 and Sb2S3 as secondary phases. Morphology and elemental detection were done by scanning electron microscopy and energy dispersive X-ray analysis. X-ray photoelectron spectroscopic studies showed the depthwise composition of the films. Optical properties were determined by UV–vis–IR transmittance and reflection spectral analysis. AgSb(S x Se1?x )2 formed at different conditions was incorporated in PV structures glass/FTO/CdS/AgSb(S x Se1?x )2/C/Ag. Chemically deposited post-annealed CdS thin films of various thicknesses were used as window layer. J–V characteristics of the cells were measured under dark and AM1.5 illumination. Analysis of the J–V characteristics resulted in the best solar cell parameters of V oc = 520 mV, J sc = 9.70 mA cm?2, FF = 0.50 and η = 2.7 %. 相似文献
4.
M. C. Kao H. Z. Chen S. L. Young 《Applied Physics A: Materials Science & Processing》2010,98(3):595-599
The preferred (002) orientation zinc oxide (ZnO) nanocrystalline thin films have been deposited on FTO-coated glass substrates
by sol–gel spin-coating technology and rapid thermal annealing for use in dye-sensitized solar cells (DSSC). The effects of
preannealing temperature (100 and 300°C) on the microstructure, morphology and optical properties of ZnO thin films were studied.
The ZnO thin films were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM) and Brunauer–Emmett–Teller
(BET) analysis. The photoelectric performance of DSSC was studied by I–V curve and the incident photon-to-current conversion efficiency (IPCE), respectively. From the results, the intensities of
(002) peaks of ZnO thin films increases with increasing preannealing temperature from 100°C to 300°C. The increase in pore
size and surface area of ZnO films crystallized at the increased preannealing temperature contributed to the improvement on
the absorption of N3 dye onto the films, the short-circuit photocurrent (J
sc) and open-circuit voltage (V
oc) of DSSC. The higher efficiency (η) of 2.5% with J
sc and V
oc of 8.2 mA/cm2 and 0.64 V, respectively, was obtained by the ZnO film preannealed at 300°C. 相似文献
5.
Indium–tin oxide films obtained by DC magnetron sputtering for improved Si heterojunction solar cell applications 下载免费PDF全文
《中国物理 B》2015,(11)
The indium–tin oxide(ITO) film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction(HJ) solar cells. To obtain high transmittance and low resistivity ITO films by direct-current(DC) magnetron sputtering, we studied the impacts of the ITO film deposition conditions, such as the oxygen flow rate,pressure, and sputter power, on the electrical and optical properties of the ITO films. ITO films of resistivity of 4×10-4?·m and average transmittance of 89% in the wavelength range of 380–780 nm were obtained under the optimized conditions:oxygen flow rate of 0.1 sccm, pressure of 0.8 Pa, and sputtering power of 110 W. These ITO films were used to fabricate the single-side HJ solar cell without an intrinsic a-Si:H layer. However, the best HJ solar cell was fabricated with a lower sputtering power of 95 W, which had an efficiency of 11.47%, an open circuit voltage(V oc) of 0.626 V, a filling factor(FF) of 0.50, and a short circuit current density(J sc) of 36.4 m A/cm2. The decrease in the performance of the solar cell fabricated with high sputtering power of 110 W is attributed to the ion bombardment to the emitter. The V oc was improved to 0.673 V when a 5 nm thick intrinsic a-Si:H layer was inserted between the(p) a-Si:H and(n) c-Si layer. The higher V oc of 0.673 V for the single-side HJ solar cell implies the excellent c-Si surface passivation by a-Si:H. 相似文献
6.
Chao Wang Yanli Mao Xiangbo Zeng 《Applied Physics A: Materials Science & Processing》2013,110(1):41-45
In this paper we study the electro-optical behavior and the application of indium–tin oxide (ITO) and aluminum-doped zinc oxide (AZO) bilayer thin films for silicon solar cells. ITO–AZO bilayer thin films were deposited on glass substrates using radio-frequency magnetron sputtering. The experimental results show that a decrease in the electrical resistivity of the ITO–AZO bilayer thin films has been achieved without significant degradation of optical properties. In the best case the resistivity of the bilayer films reached a minimum of 5.075×10?4 Ω?cm when the thickness of the AZO buffer layer was 12 nm. The ITO–AZO bilayer films were applied as the front electrodes of amorphous silicon solar cells and the short-circuit current density of the solar cells was considerably increased. 相似文献
7.
Electron beam evaporation deposition of cadmium sulphide and cadmium telluride thin films: Solar cell applications7 下载免费PDF全文
Cadmium sulphide (CdS) and cadmium telluride (CdTe) thin films are deposited by electron beam evaporation. Atomic force microscopy (AFM) reveals that the root mean square (RMS) roughness values of the CdS films increase as substrate temperature increases. The optical band gap values of CdS films increase slightly with the increase in the substrate temperature, in a range of 2.42-2.48 eV. The result of Hall effect measurement suggests that the carrier concentration decreases as the substrate temperature increases, making the resistivity of the CdS films increase. CdTe films annealed at 300 ℃ show that their lowest transmittances are due to their largest packing densities. The electrical characteristics of CdS/CdTe thin film solar cells are investigated in dark conditions and under illumination. Typical rectifying and photovoltaic properties are obtained. 相似文献
8.
To better understand the electronic and chemical properties of wide-gap oxide surfaces at the atomic scale, experimental work has focused on epitaxial films on metal substrates. Recent findings show that these films are considerably thinner than previously thought. This raises doubts about the transferability of the results to surface properties of thicker films and bulk crystals. By means of density-functional theory and approximate GW corrections for the electronic spectra we demonstrate for three characteristic wide-gap oxides (silica, alumina, and hafnia) the influence of the substrate and highlight critical differences between the ultrathin films and surfaces of bulk materials. Our results imply that monolayer-thin oxide films have rather unique properties. 相似文献
9.
Mo thin films are deposited on soda lime glass (SLG) substrates using DC magnetron sputtering. The Mo film thicknesses are varied from 0.08 μm to 1.5 μm to gain a better understanding of the growth process of the film. The residual stresses and the structural properties of these films are investigated, with attention paid particularly to the film thickness dependence of these properties. Residual stress decreases and yields a typical tensile-to-compressive stress transition with the increase of film thickness at the first stages of film growth. The stress tends to be stable with the further increase of film thickness. Using the Mo film with an optimum thickness of 1 μm as the back contact, the Cu(InGa)Se2 solar cell can reach a conversion efficiency of 13.15%. 相似文献
10.
Keymeulen HR de Jeu WH Slattery JT Veum M 《The European physical journal. E, Soft matter》2002,9(5):443-446
We present a model for the structure of binary mixtures of smectic compounds in freely suspended films of 2-7 layers. The compounds are the hexyl (6AB) and dodecyl (10AB) homologues of p, p'-dialkylazoxybenzene that differ by about 40% in molecular length. X-ray reflectivity indicates that no demixing occurs between 6AB and 10AB molecules, while also there is no indication found of increased roughness at the film surfaces. However, the surface layers are somewhat expanded compared to the interior layers. This can be explained by backfolding of the dodecyl end chains of 10AB molecules at the surface via two gauche kinks, which ensures dense packing. This model is supported by surface tension measurements that indicate an increased amount of alkyl groups at the surfaces. 相似文献
11.
H. Spillmann P.R. Willmott M. Morstein P.J. Uggowitzer 《Applied Physics A: Materials Science & Processing》2001,73(4):441-450
High-quality thin films of ZrN, ZrxAlyN and ZrxGayN have been grown by pulsed reactive crossed-beam laser ablation using Zr, Zr-Al and Zr-Ga ablation targets, respectively,
and a N2 gas pulse. The films were characterized for their chemical, crystallographic and tribological properties. All the films had
very low impurity levels and a cubic rock salt crystal structure over the entire investigated temperature range between room
temperature and 600 °C. High-quality epitaxial films could be grown on Si (001) at 400 °C, though the crystallinity was disrupted
at 525 °C by Si diffusion into the film bulk and the formation of ZrSi2 crystallites. Films grown on stainless steel were polycrystalline. The ratios of the metals in the alloy targets were in
general not equal to those in the films: the Al content in the ZrxAlyN films was lower than the target value, which we attribute to differential scattering in the ablation plume. The Ga content
in the ZrxGayN films fell with increasing substrate temperature, indicative of re-evaporation of Ga from the substrate surface. Those ZrxGayN films with the highest Ga content, grown at the lowest temperatures, were particularly nitrogen-deficient, which we attribute
to the low reactivity of Ga with N2. The ZrxAlyN films had an exceptionally low coefficient of friction (0.20) versus steel and the greatest nanohardness of 28 GPa.
Received: 9 November 2000 / Accepted: 14 November 2000 / Published online: 28 February 2001 相似文献
12.
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14.
We observe >6% efficiency enhancement in silicon thin film solar cell using a p-type microcrystalline silicon oxide (μc-SiO:H) contact layer between transparent conducting oxide (TCO) electrode and the hydrogenated amorphous silicon (a-Si:H) layer. The role of the above contact layer is to reduce the Schottky barrier effect as well as the hetero-junction barrier formation at the interface. Despite its nanometer scale thickness, the properties of the contact layer significantly affect the solar parameters. Based on our results, p-type doped μc-SiO:H can be an ideal material as a contact layer due to its good optical response without noticeable degradation in its electrical property. 相似文献
15.
Samples with nodular defects grown from gold nanoparticles are prepared,and laser-induced damage tests are conducted on them.Nodular defects,which are in critical state of damage,are cross-sectioned by focusing on the ion beam and by imaging using a field emission scanning electron microscope.The crosssectional profile shows that cracks are generated and propagated along the nodular boundaries and the HfO2/SiO2 interface,or are even melted.The thermomechanical process induced by the heated seed region is analyzed based on the calculations of temperature increase and thermal stress.The numerical results give the critical temperature of the seed region and the thermal stress for crack generation,irradiated with threshold fluence.The numerical results are in good agreement with the experimental ones. 相似文献
16.
Prashant Kumar 《Applied Physics A: Materials Science & Processing》2010,98(2):473-479
DC electric-field mediated nanocrystallization of thermally evaporated silicon thin films with nickel as seed/cap layer has
been attempted in complete absence of any external heat input. When 60 nm Si thin film coated onto 5 nm Ni thin film was treated
by a direct current (DC) electric field (up to 3.3 kV/cm up to 5 minutes) after the deposition, amorphous silicon thin films
became nanocrystalline (6–10 nm). Silicon nanograins (average diameter 90 nm) grow to larger sizes (average diameter 240 nm)
with sharpening of grain size distribution. Huge grain growth (4-fold increase) has been observed when nickel was used as
cap layer (5 nm Ni/60 nm Si). XRD data show the signature of nickel silicide formation on the surface in nickel cap layer
case. Field treatment has changed the optical absorption edge (shifts left in nm units) and the refractive index of silicon
thin film when nickel was used as under layer, and an almost negligible effect on the optical properties has been observed
when nickel was used as cap layer. 相似文献
17.
Reiter G 《The European physical journal. E, Soft matter》2002,8(2):251-255
I present some tentative ideas on the possibility of plastic deformation which might be relevant in ultra-thin polymer films
at temperatures close but below the glass transition temperature. Several possible sources for sufficiently strong forces
are discussed. The relevance of such forces in experiments aiming at determining thin-film properties like the glass transition
temperature, thermal expansion or surface morphology is discussed.
Received 19 September 2001 and Received in final form 5 December 2001 相似文献
18.
Michael Seibt Reda Khalil Vitaly Kveder Wolfgang Schr?ter 《Applied Physics A: Materials Science & Processing》2009,96(1):235-253
Predominant dislocation types in solar silicon are dissociated into 30°- and 90°-partials with reconstructed cores. Besides
shallow 1D-band localized in their strain field and a quasi-2D band at the stacking fault connecting the two partials, the
existence of several intrinsic core defects with deep lying levels has been demonstrated by electron spin resonance. The majority
of core defects occur in nonequilibrium situations and, with the exception of a small EPR-signal assigned to a reconstruction
defect, vanish after careful annealing above 800°C. There is good evidence now that part of deep levels observed in dislocated
silicon is associated with impurities, especially with transition metal impurities. Electron-hole-pair recombination at a
dislocation mainly runs via its shallow bands and is strongly increased by impurities bound to its core or in the strain field.
The concentration of these impurities can be reduced by gettering processes to such a low level that radiative recombination
at dislocations yields a luminescence efficiency of 0.1% at room temperature.
A quite coherent picture has emerged for metal impurity precipitation in silicon. Early stages of precipitation in defect-free
silicon are characterised by kinetically selected metastable defects forming as a result of large chemical driving forces
for precipitation. Such defects are associated with deep level spectra which show the properties of extended multielectron
defects. The evolution of the system to energetically more favourable configurations proceeds via ordinary particle coarsening
but also via internal ripening, a process reminiscent of the above-mentioned metastable defects. Electronically, the defects
evolve into metal-like inclusions which in general seem to act as strong recombination centers for minority carriers. In the
presence of dislocations metastable defects quickly transform into equilibrium structures in the course of precipitation or
do not form at all. In the presence of several metal impurities silicide precipitates which can be described as solid solutions
of the respective metal atoms are observed, which is at least qualitatively in accord with ternary phase diagrams. Like single-metal
silicide precipitates, strong minority carrier recombination is also typical for those multi-metal silicide particles. 相似文献
19.
《Current Applied Physics》2015,15(2):59-63
We have synthesized an efficient Cu2ZnSn(SxSe1−x)4 (CZTSSe) absorbers by using single-step rapid thermal sulfo-selenization process of sputtered stack metallic precursor (Zn/Sn/Cu) films. The structural and morphological studies confirm that the suitability of the rapid thermal sulfo-selenization process for the synthesis of a CZTSSe absorber without any secondary phases with large grains. The annealing atmosphere with a mixed-chalcogen source enhances the grain growth of the CZTSSe absorber as compared with pure Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) absorbers. The CZTSSe thin film solar cell shows the best conversion efficiency of ∼7%. 相似文献
20.
《Current Applied Physics》2015,15(5):622-631
Lithium (Li) (0–5 wt%) doped V2O5 thin films were spray deposited at 450 °C onto ITO substrates. Structural analysis using X-ray diffraction and Raman spectroscopy revealed orthorhombic phase of the films. In addition to the V2O5 phase, presence of VO2 peaks due to high deposition temperature is also evident from structural and optical characterization. The non-stoichiometric nature of the films due to loss of the terminal O atom was confirmed from Raman spectroscopy. The direct band gap, indirect bandgap, and phonon energies were also calculated from optical studies. Different charge states of vanadium ions present in the film were identified from X-ray photoelectron spectroscopy study. Results from cyclic voltammetry experiments reflected significant differences between the undoped and Li doped V2O5 samples. Transport properties by Hall-effect measured at room temperature indicated significant increase in conductivity, carrier concentration and mobility of V2O5 thin films on doping with Li. A Dye Sensitized Solar Cell (DSSC) was fabricated using mobility enhanced 5 wt% Li doped V2O5 film as photoanode and its efficiency was found to be 2.7%. A simple electrochromic cell is fabricated using undoped V2O5 thin film to demonstrate the colour change. 相似文献