bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of novel fluorinated aromatic polyimides derived from 1,1‐bis(4‐amino‐3,5‐dimethylphenyl)‐1‐(3,5‐ditrifluoromethylphenyl)‐2,2,2‐trifluoroethane and various aromatic dianhydrides
Authors: Li Hong‐Shen , Liu Jin‐Gang , Rui Jia‐Ming , Fan Lin , Yang Shi‐Yong 
Published: March 2006

AbstractA novel fluorinated aromatic diamine, 1,1‐bis(4‐amino‐3,5‐dimethylphenyl)‐1‐(3,5‐ditrifluoromethylphenyl)‐2,2,2‐trifluoroethane (9FMA), was synthesized by the coupling reaction of 3′,5′‐ditrifluoromethyl‐2,2,2‐trifluoroacetophenone with 2,6‐dimethylaniline under the catalysis of 2,6‐dimethylaniline hydrochloride. A series of fluorinated aromatic polyimides were synthesized from 9FMA and various aromatic dianhydrides, including pyromellitic dianhydride, 3,3′4,4′‐biphenyl tetracarboxylic dianhydride, 4,4′‐oxydiphthalic anhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), and 4,4′‐hexafluoroisopropylidene diphthalic anhydride, via a high‐temperature, one‐stage imidization process. The inherent viscosities of the polyimides ranged from 0.37 to 0.74 dL/g. All the polyimides were quickly soluble in many low‐boiling‐point organic solvents such as tetrahydrofuran, chloroform, and acetone as well as some polar organic solvents such as N‐methyl‐2‐pyrrolidinone, N,N′‐dimethylacetamide, and N,N′‐dimethylformamide. Freestanding fluorinated polyimide films could be prepared and exhibited good thermal stability with glass‐transition temperatures of 298–334 °C and outstanding mechanical properties with tensile strengths of 69–102 MPa and elongations at break of 3.3–9.9%. Moreover, the polyimide films possessed low dielectric constants of 2.70–3.09 and low moisture absorption (<0.58%). The films also exhibited good optical transparency with a cutoff wavelength of 303–351 nm. One polyimide (9FMA/BTDA) also exhibited an intrinsic negative photosensitivity, and a fine pattern could be obtained with a resolution of 5 μm after exposure at the i‐line (365‐nm) wavelength. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2665–2674, 2006
Reinforcement effect of MAA on nano‐CaCo3‐filled EPDM vulcanizates and possible mechanism
Authors: Zhou Yabin , Wang Shifeng , Zhang Yinxi , Zhang Yong 
Published: March 2006

AbstractMethacrylic acid (MAA) was used as in situ surface modifier to improve the interface interaction between nano‐CaCO3 particle and ethylene–propylene–diene monomer (EPDM) matrix, and hence the mechanical properties of nano‐CaCO3‐filled EPDM vulcanizates. The results showed that the incorporation of MAA improved the filler–matrix interaction, which was proved by Fourier transformation infrared spectrometer (FTIR), Kraus equation, crosslink density determination, and scanning electron microscope (SEM). The formation of carboxylate and the participation of MAA in the crosslinking of EPDM indicated the strong filler–matrix interaction from the aspect of chemical reaction. The results of Kraus equation showed that the presence of MAA enhanced the reinforcement extent of nano‐CaCO3 on EPDM vulcanizates. Crosslink density determination proved the formation of the ionic crosslinks in EPDM vulcanizates with the existence of MAA. The filler particles on tensile fracture were embedded in the matrix and could not be observed obviously, indicating that a strong interfacial interaction between the filler and the matrix had been achieved with the incorporation of MAA. Meanwhile, the presence of MAA remarkably increased the modulus and tensile strength of the vulcanizates, without negative effect on the high elongation at break. Furthermore, the ionic bond was thought to be formed only on filler surface because of the absolute deficiency of MAA, which resulted in the possible structure where filler particles were considered as crosslink points. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1226–1236, 2006
Synthesis and Raman spectra of Si‐nanowires
Authors: Su Z. X. , Sha J. , Niu J. J. , Liu J. X. , Yang D. R. 
Published: March 2006

AbstractRandomly arrayed silicon nanowires (SiNWs) were synthesized by thermal evaporation of sulfur powders and silicon wafer; zinc sulfide and silicon; SiO powder. Orderly arrayed SiNWs were grown in the anodized aluminium oxide (AAO) template using the CVD method. The Raman spectra of the SiNWs were detected for the samples synthesized in different ways, and the temperature dependence of the Raman spectra of the samples was studied. Combining the structural analysis and Raman data of the samples, phonon‐confinement model and the anharmonic process were connected to the discussion of the Raman spectra. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Silicon‐based narrow‐bandgap thin‐film semiconductor materials: polycrystalline SiGe prepared by reactive thermal CVD
Authors: Zhang Jianjun , Shimizu Kousaku , Zhao Ying , Geng Xinhua , Hanna Jun‐ichi 
Published: March 2006

AbstractIn this work, the mechanisms of reactive thermal CVD are discussed and the influences of various deposition parameters on crystallinity, composition, uniformity and reproducibility are clarified. Based on optimization of deposition parameters, we obtained device‐grade polycrystalline SiGe (poly‐SiGe) thin films with high crystallinity of >95%, high uniformity of >80% and high reproducibility of >85% at 450 °C. The results presented in this paper proved that polycrystalline SiGe films deposited by reactive thermal CVD are suitable for device application. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
R&D activities of silicon‐based thin‐film solar cells in China
Authors: Zhao Yuwen , Geng Xinhua , Wang Wenjing , Li Xudong , Xu Ying 
Published: March 2006

AbstractThe status and progress of R&D activities of silicon‐based thin‐film solar cells in China are described briefly in this paper, including amorphous Si solar cells and microcrystalline Si film solar cells based on PECVD technology and polycrystalline film solar cells based on RTCVD technology. Especially, the microcrystalline thin‐film solar cells and the tandem solar cells of amorphous Si with microcrystalline Si have made great progress. The polycrystalline film solar cells have made remarkable achievements as well. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Germanium effect on oxygen‐related defects in Czochralski silicon
Authors: Yang Deren , Chen Jiahe , Li Hong , Ma Xiangyang , Tian Daxi , Li Liben , Que Duanlin 
Published: March 2006

AbstractThe behaviours of germanium doped in Czochralski (CZ) silicon have attracted considerable attention in recent years. In this article, a review concerning recent processes in the study about oxygen related defects in germanium‐doped CZ (GCZ) silicon is presented. The formation of oxygen precipitates during CZ silicon growth can be improved by germanium, and the oxygen precipitation during thermal cycles can be enhanced, so that the internal gettering (IG) ability of GCZ silicon wafers for metallic impurities is improved. Meanwhile, the morphology of oxygen precipitates can be changed in GCZ silicon. Thermal donors (TDs) can be suppressed by germanium doping as the result of the reaction between germanium and point defects, while new donors (NDs) can be strongly enhanced in GCZ silicon because of a process associated with the nucleation enhancement of oxygen precipitates with germanium doping. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wafering of silicon crystals
Authors: Möller H. J. 
Published: March 2006

AbstractMulti‐wire sawing is the main slicing technique for large multi‐ and monocrystalline silicon crystals in the photovoltaic and microelectronic industry. This paper describes the basic mechanisms by which slicing is achieved and develops a model for the material removal rate. It is shown that the hydrodynamic behavior of the slurry and the elastic interaction with the wire are an important aspect that has to be taken into account. The material removal occurs by the indentation of free floating SiC particles under the pressure of the wire. The microscopic fracture processes under the indented particles have been investigated and are described quantitatively. The numerical and experimental results are compared. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Semiconductor wafer bonding
Authors: Reiche M. 
Published: March 2006

AbstractWhen mirror‐polished, flat, and clean wafers are brought into contact, they are locally attracted to each other and adhere or bond. This phenomenon is known as semiconductor wafer bonding. Different adhesion forces (van der Waals forces, hydrogen bonding) are the reason for the bonding effect at room temperature. The different bonding mechanisms acting in dependence on the surface conditions (hydrophilic, hydrophobic) are reviewed. Variations of the properties of bonded interfaces (structural, mechanical, electrical) during annealing are discussed. The focus is on low‐temperature bonding techniques. Reasons for the formation of interface defects are presented. Applications of semiconductor wafer bonding for future developments are briefly summarized. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Advanced defect and impurity diagnostics in silicon based on carrier lifetime measurements
Authors: Warta W. 
Published: March 2006

AbstractAn overview is given on recent developments at Fraunhofer ISE in the field of diagnostic techniques based on carrier lifetime measurements. The status of the different lifetime spectroscopy methods and the diagnostic capabilities of infrared carrier lifetime imaging are outlined. A combination of short acquisition times with high spatial resolution and high dynamic range under (quasi‐)steady‐state conditions gives IR lifetime imaging a high potential for the application in material and process characterization. Measuring in the emission mode provides access to the temperature dependence of lifetime and thus spatially resolved temperature dependent lifetime spectroscopy. Images of injection dependent lifetimes may be measured. For the anomalous increase at low injection a modeling description was developed. Assuming carrier trapping as origin of the increase, spatially resolved trap parameter analysis is possible. A new approach to suppress the anomalous increase by the application of sub‐bandgap light was demonstrated. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure‐induced transformations of nitrogen implanted into silicon
Authors: Akhmetov V. D. , Misiuk A. , Barcz A. , Richter H. 
Published: March 2006

AbstractCzochralski (CZ) Si samples implanted with nitrogen, with doses 1017 ion/cm2 and 1018 ion/cm2, at 140 keV, were studied by means of Fourier transform infrared spectroscopy after annealing at 1130 °C/5 h under different hydrostatic pressures, from 1 bar to 10.7 kbar. It has been found for each pressure applied, that the increased nitrogen dose leads to transformation of the broadband spectra to the fine structure ones, corresponding to crystalline silicon nitride. The spectral position of observed sharp peaks in the investigated pressure region is red shifted in comparison to that for the peaks of crystalline silicon oxynitride found recently by other investigators in nitrogen‐containing poly‐Si as well as in a residual melt of nitrogen‐doped CZ‐Si. The application of the pressure during annealing results in further red shift of the nitrogen‐related bands. The observed decrease of frequency of vibrational bands is explained in terms of the pressure induced lowered incorporation of oxygen into growing oxynitride phase. Secondary ion mass spectrometry data reveal the decrease of oxygen content in implanted layer with increasing pressure during annealing. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preface: phys. stat. sol. (a) 203/4
Authors: Kittler Martin , Yang Deren 
Published: March 2006

AbstractThis issue of physica status solidi (a) contains the majority of papers presented at the 2nd Sino–German Symposium “The Silicon Age” which was held at the Lindner Hotel Cottbus, Germany, 19–24 September 2005. This meeting followed the 1st Symposium “Progress in Silicon Materials” held in June 2002 in Hangzhou, P.R. China. 8 Chinese and 14 German scientists from universities, research institutes and industry were invited to present their views about different aspects of silicon.There was a continuous progress in silicon materials development during the last 40–50 years, driven by the need of the IC industry for better and larger monocrystalline silicon wafers. Moreover, low‐cost crystalline silicon now dominates the world's production of solar cells in the photovoltaics industry. Furthermore, there are intensive research activities worldwide for on‐chip integration of Si‐based photonics in CMOS technology. In addition, new areas being connected with silicon are starting to appear, namely Si‐based biochips and nanoelectronics. Silicon, one can reasonably argue, is already the most investigated of all materials. However, there is still a need for continuation of research and development regarding numerous aspects of Si and also SiGe, including related technologies, advanced diagnostics or the role of crystal defects, which are the working fields of many laboratories all over the world. This was also shown by the presentations at the symposium and can be found in the contributions contained in this issue.The organizers would like to thank the participants for their high level contributions and discussions during the symposium. This intensive and open communication allowed the participants to create synergies between the different fields of silicon research and also to build up relationships for cooperation between Chinese and German research groups.Finally, we would like to thank the Sino–German Science Center for the financial support of the symposium.
Spin waves of the spin‐polarized electron gas in semimagnetic quantum wells
Authors: Perez F. , Jusserand B. , Richards D. , Karczewski G. 
Published: March 2006

AbstractSpin flip waves and spin density fluctuations of a two‐dimensional spin‐polarized electron‐gas in a semimagnetic Cd1–0.008Mn0.008Te quantum well are observed by Resonant Raman Scattering. Application of a magnetic field splits the spin subbands and a static spin polarization is induced. Wavevector and field experimental dispersions are very well reproduced by Local Spin Density Approximation calculations including recent Quantum Monte Carlo evaluation of coulomb correlations corrections. We show how to extract the spin polarization degree. A maximum value of 35% is deduced from measurements. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin coherence of two‐dimensional electron gas in CdTe/(Cd,Mg)Te quantum wells
Authors: Zhukov E. A. , Yakovlev D. R. , Bayer M. , Karczewski G. , Wojtowicz T. , Kossut J. 
Published: March 2006

AbstractElectron spin coherence has been studied in CdTe/(Cd,Mg)Te quantum wells with a low‐dense two‐dimensional electron gas by means of pump–probe Kerr rotation technique. Spin dephasing time of 30 ns has been measured in the limit of zero magnetic fields and at a temperature of 1.9 K. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exchange interaction in magnetic HgMnTe quantum well structure
Authors: Liu Jian , Buhmann Hartmut , Novik Elena G. , Gui Yongsheng , Hock Volkmar , Becker Charles R. , Molenkamp Laurens W. 
Published: March 2006

AbstractLow temperature magnetotransport measurements have been used to study the exchange interactions in Hg1–x Mnx Te magnetic quantum wells (QWs). An analysis of Shubnikov–de Haas oscillations in conjunction with 8 × 8 k · p bandstructure calculations allow the exchange constants N 0α and N 0β , the antiferromagnetic temperature T 0, and the effective spin S 0 to be determined. The latter displays a distinct temperature dependence and appears to be enhanced compared with bulk materials of equivalent Mn concentrations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonon properties and doping of Zn1–xMnxSe epilayers grown by molecular‐beam epitaxy
Authors: Agarwal K. C. , Daniel B. , Hofmann T. , Schubert M. , Klingshirn C. , Hetterich M. 
Published: March 2006

AbstractWe present far‐infrared (FIR) reflection studies for Zn1–x Mnx Se. It is found that a modified oscillator model provides improved agreement with the experimental data. Our results suggest an intermediate‐mode behavior for the optical phonon modes in Zn1–x Mnx Se. In addition to the known ZnSe‐like and MnSe‐like phonon resonances a weak defect‐related feature ‘D’ is found below the MnSe‐like phonon band. The frequency of this feature shows a temperature and Mn dependent red‐shift. Furthermore, the observation of a drastic reduction in the free‐electron concentration with increasing Mn content suggests a compensation effect related to the formation of Mn‐related defect complexes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Concentration and size dependence of the dynamics of the Mn 3d5 luminescence in wire‐like arrangements of (Zn,Mn)S nanoparticles
Authors: Chen L. , Kampmann J. , Klar P. J. , Heimbrodt W. , Brieler F. J. , Fröba M. 
Published: March 2006

Abstract(Zn,Mn)S nanoparticles with Mn concentrations ranging from 1% to 30% and in a wire‐like arrangement were formed inside mesoporous SiO2 matrices of various pore diameters. The nanoparticles were characterised using photoluminescence and excitation spectroscopy. It is found, that the Mn2+ ions are incorporated on cation lattice sites replacing Zn. The decay times of the internal Mn2+ (3d5) luminescence are studied in detail by time resolved spectroscopy over more than 5 orders of magnitude in intensity. A concentration and a remarkable size dependence of the time behaviour has been observed indicating a geometry dependence of the energy transfer processes within the Mn system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of single ZnO nanowires
Authors: Wischmeier L. , Bekeny C. , Voss T. , Börner S. , Schade W. 
Published: March 2006

AbstractThe optical properties of single ZnO nanowires with diameters <200 nm are analyzed. A comparison of the photoluminescence properties of the as‐grown ensemble and of an individual nanowire is given. The temperature dependence of the individual nanowire photoluminescence shows the same behavior as that of bulk material due to the wire diameter being very large compared to the exciton Bohr radius of ZnO. Furthermore, high excitation‐density measurements performed on an individual nanowire are presented in which a sharp line is observed resulting from resonator effects inside the wire. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of ZnO (000$ \bar 1$)/Al2O3 (11$ \bar 2$0) surface morphologies using plasma‐assisted molecular beam epitaxy
Authors: Xu Huaizhe , Ohtani Keita , Yamao Miyuki , Ohno Hideo 
Published: March 2006

AbstractThe surface morphologies of ZnO thin films grown on Al2O3 (11$ \bar 2 $0) (a‐plane sapphire) substrate by plasma‐assisted molecular beam epitaxy (PAMBE) were systematically investigated by in situ reflection high energy electron diffraction (RHEED) and ex situ atomic force microscopy (AFM) as a function of Zn beam flux intensity and substrate temperature. The ZnO films are uniquely (000$ \bar 1 $) oriented with no trace of secondary orientation. A phase diagram for ZnO growth was established, which described the ZnO growth mode transition at fixed O2 flow rate of 0.3 sccm. For the growth at 750 °C with Zn beam flux of 3.6 × 10–7 Torr, the RHEED showed a (3 × 3) pattern and a smooth surface represented by atomically flat terraces and half unit cell high steps (∼0.26 nm, a charge neutral unit of ZnO) was observed corresponding to a monolayer or bilayer thickness of Zn–O along the c ‐axis of (000$ \bar 1 $) ZnO. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical investigation of non‐equilibrium carrier dynamics in differently doped VGF‐grown ZnTe single crystals
Authors: Aleksiejūnas R. , Kadys A. , Jarašiūnas K. , Lovergine N. , Asahi T. 
Published: March 2006

AbstractWe applied a time‐resolved FWM technique to study the dynamics of photoexcited carriers in differently doped VGF‐grown ZnTe crystals at room temperature. We observed a fast carrier trapping to deep levels in phosphorus doped and undoped samples. The measurements at below and above band‐gap excitations revealed the much higher concentration of these levels near the surface than in the bulk in both samples. The concentration of deep traps has been estimated for phosphorus doped sample N T = (1 – 2) × 1015 cm–3 in the bulk and N = (3 – 5) × 1018 cm–3 near the surface. In the undoped sample these traps are present at much higher concentration. The electron and hole mobilities μ n = (500 ± 28) cm2/Vs and μ h = (16 ± 6) cm2/Vs were estimated from the measured diffusion coefficient values D = (12.5 ± 0.7) cm2/s in the p‐type sample and D = (0.8 ± 0.3) cm2/s in the semi‐insulating one. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the lattice constant of CrS from Mn1–xCrxS MBE epitaxial layers
Authors: David L. , Prior K. A. 
Published: March 2006

AbstractA series of Mn1–x Crx S epitaxial structures have been grown with the composition ZnSe/Mn1–x Crx S/ZnSe with varying x . X‐ray Interference measurements were used to determine the layer thicknesses and compositions, and by varying the lattice parameter of CrS an improved fit was obtained. The lattice parameter of CrS was found to be 5.387 ± 0.025 Å. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron paramagnetic resonance of Mn2+ ions in CdTe detected by coherent Raman spectroscopy
Authors: Smith L. C. , Wolverson D. , Bingham S. J. , Davies J. J. 
Published: March 2006

AbstractWe report the first application of the coherent Raman‐detected ESR spectroscopy (CRESR) technique to a dilute magnetic semiconductor. A bulk crystal of cadmium magnanese telluride with low manganese content was chosen for this study as (Cd,Mn)Te is a well‐characterized model system for which the relevant parameters are accurately known. We consider in detail the information that the CRESR spectra contain on the hyperfine interaction of the Mn2+ 3d5 electrons with the manganese nuclei and the effects of the cubic crystal field. This work opens up the possibility of CRESR studies of other, less well‐known, magnetic semiconductors and their heterostructures. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Slow‐mode degradation mechanism and its control in new bright and long‐lived ZnSe white LEDs
Authors: Adachi Masahiro , Ando Koshi , Abe Tomoki , Inoue Noboru , Urata Akihiro , Tsutsumi Sueyuki , Hashimoto Yutaka , Kasada Hirofumi , Katayama Koji , Nakamura Takao 
Published: March 2006

AbstractThis paper presents slow‐mode degradation mechanism of ZnSe‐based white LEDs. A systematic study has been made from a viewpoint of microscopic point defect reaction such as generation and migration in both device active layer (ZnCdSe/ZnSe MQW) and p‐type ZnMgSSe cladding layer utilizing DLTS/ ICTS, SSRM (scanning spreading resistance microscope), and EL (electroluminescence)‐imaging techniques, coupled with device aging experiments. We have found two different degradation stages (1st and 2nd stages) in the slow‐mode degradation, which are caused by quite different microscopic point defect species. The 1st stage is induced by the long‐diffusion of H0‐center (nitrogen‐complex deep hole trap in p‐cladding layer), forming high‐density dark‐spots in the MQW active layer. This active center is generated only in the stress‐stimulated condition such as thermal or device fabrication process. After controlling the initial concentration of the H0 center, we have observed no detectable new dark‐spots during device operation, leading to fairly long device‐lifetime (∼1000 h). This 2nd stage has appeared as a carrier (hole) reduction in the p‐type cladding layer. This final degradation stage is found to take place by an increase of shallow compensating donor‐like centers in p‐type cladding layer (ZnMgSSe). Based on these insights on the microscopic point defect reaction, we have developed (new) double cladding i‐ZnMgBeSe/p‐ZnMgSSe white‐LEDs, which has exhibited long device lifetime of over 10000 h. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)