bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real time spectroscopic ellipsometry of sputtered CdTe, CdS, and CdTe1−xSx thin films for photovoltaic applications
Authors: Li Jian , Podraza N. J. , Collins R. W. 
Published: March 2008

AbstractReal time spectroscopic ellipsometry (RTSE) has been applied to study the deposition of polycrystalline CdTe, CdS, and CdTe1–x Sx thin films on crystalline silicon wafer substrates as well as the formation of CdS/CdTe and CdTe/CdS heterojunctions, all using a magnetron sputtering process. For CdTe and CdS, the key process variable is deposition temperature (T). The nucleation and growth behaviors of CdTe and CdS show strong variations with T and this influences the ultimate grain size of the polycrystalline films. For the co‐sputtered CdTe1–x Sx alloys, the key variables are the rf power levels applied to the CdTe and CdS targets and thus the resulting composition x. The dielectric functions of the alloys have been used as a database for real time investigation of inter‐diffusion at the CdS/CdTe and CdTe/CdS heterojunctions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mass spectrometry at a Ar/SF6/O2 chemically reactive plasma jet
Authors: Arnold Th. , Schindler A. 
Published: March 2008

AbstractChemically reactive plasma jets are tools for the treatment of surfaces with respect to material removal, deposition, and chemical modification. The plasma under investigation is created by introducing microwave power into a Ar/SF6/O2 subsonic gas flow to produce chemically reactive species for dry etching. In Ar/SF6/O2 plasma jets chemical reactions induced by electron impact form a large variety of SFx and SOx Fy radicals as well as free fluorine atoms. Low potential mass spectrometry was used to investigate the spatial structure of the plasma jet depending on gas composition. The mass spectra give information about different characteristic zones, which can be designated as the active and passive plasma zone, i.e. the dissociation and recombination zone, respectively. The knowledge of the kind of plasma‐chemical mechanisms and their spatial distributions is necessary to optimize gas composition and geometric parameters for effective silicon based material etching. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic optical matrix elements in strained GaN‐quantum wells with various substrate orientations
Authors: Yamaguchi A. Atsushi 
Published: March 2008

AbstractPolarization properties in compressively strained III‐nitride quantum wells (QWs) with various substrate orientations are numerically calculated using the 6×6 k·p Hamiltonian. It is shown that in‐plane optical anisotropies strongly depend on substrate orientation, QW width, and strain components. In particular, quantum confinement and compressive strain have the opposite effects on the anisotropies, and the in‐plane polarization degree is determined by the competition of these two effects. These characteristics are also verified by analytical calculations. On the basis of the calculation results, the structural design of laser diodes on semipolar and nonpolar substrates is also discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High drain current and low on resistance normally‐off‐mode AlGaN/GaN junction HFETs with a p‐type GaN gate contact
Authors: Fujii T. , Nakamura S. , Mizuno K. , Nega R. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I. 
Published: March 2008

AbstractThe normally‐off‐mode junction HFETs with a p‐type GaN gate contact showing high drain current and an extremely large on/off ratio were successfully fabricated by MOVPE. The drain currents were found to be very sensitive to the surface of the u‐AlGaN barrier exposed by RIE etching. A reproducible and stable high drain current was achieved using a very thin SiN passivation layer. The maximum drain current was 1.58×10–1 A/mm at VGS = 4 V, while the drain current at VGS = 0 V was as low as 1.45×10–8 A/mm. Therefore, an on/off ratio of 107 has been achieved. The sub‐threshold swing was as small as 90 mV/dec.. The on resistance was 3.4 mΩcm2, the threshold voltage was +0.45 V, and the breakdown voltage was over 325 V. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlGaN/GaN‐based MEMS with two‐dimensional electron gas for novel sensor applications
Authors: Niebelschütz F. , Cimalla V. , Tonisch K. , Haupt Ch. , Brückner K. , Stephan R. , Hein M. , Ambacher O. 
Published: March 2008

AbstractNovel microelectromechanical resonators structures have been realized based on AlGaN/GaN heterostructures, which provide a basis for sophisticated sensor structures. There were grown on SiC substrates confining a two dimensional electron gas (2DEG). By means of the developed etching technology, freestanding resonators were patterned without degrading the sheet carrier concentration and electron mobility of the 2DEG inside the beams, which was confirmed by electrical measurements before and after the various process steps. As actuation and read out principle magnetomotive and piezoelectric effects were used, respectively. Due to the high sensitivity of the 2DEG and the chemical stability of the utilized materials these structures are suitable for chemical and biological sensor applications, where the sensitivity of the 2DEG on the surrounding environment acts as additional sensing signal, for example for simultaneous measurements of the viscosity and pH – value of a nanoliter droplet. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of a freestanding AlN substrate prepared by hydride vapor phase epitaxy
Authors: Kumagai Y. , Nagashima T. , Murakami H. , Takada K. , Koukitu A. 
Published: March 2008

AbstractA thick AlN layer was grown on a (111)Si starting substrate at 1230 ºC by hydride vapor phase epitaxy (HVPE). A 112‐μm‐thick freestanding AlN substrate was successfully prepared by removing the Si substrate using a chemical etchant. The AlN substrate was transparent with a smooth (0001) surface. Immersion of the AlN substrate in an aqueous KOH solution revealed that the AlN layer grown on the (111)Si substrate predominately has Al‐polarity. Owing to improvement of crystalline quality by thick layer growth, a near‐band‐edge (NBE) emission could be obtained at 5.92 eV in the room‐temperature photoluminescence (PL) spectrum taken at the top surface of the AlN substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and ab‐initio studies of temperature dependent InN decomposition in various ambient
Authors: Togashi R. , Kamoshita T. , Nishizawa Y. , Murakami H. , Kumagai Y. , Koukitu A. 
Published: March 2008

AbstractN‐polarity InN layers grown on (0001) sapphire substrates by hydride vapor phase epitaxy (HVPE) were annealed in atmospheric N2, H2, H2 + NH3, or N2 + NH3 ambient at various temperatures. In the N2 ambient, InN decomposition became significant above 600 °C, whereas in the H2 ambient, InN layers reacted with H2 and decomposed at very low temperatures above 350 °C. The process of InN decomposition was also investigated using a first‐principles calculation. In a system free from H2, the rate‐limiting process was found to be desorption of N atoms from the surface as atomic N (N*), whereas in the H2 ambient, the desorption of In atoms as In, InH or InH3 is the rate‐limiting process. Thus, the decomposition reactions of InN layers in the ambient in the presence and absence of H2 are different. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved light extraction efficiency of GaN‐based light emitting diodes by using needle‐shape indium tin oxide p‐contact
Authors: Ishida Fumio , Yoshimura Kazumasa , Hoshino Katsuyuki , Tadatomo Kazuyuki 
Published: March 2008

AbstractThe high‐efficiency GaN‐based light emitting diodes (LEDs) with improved light extraction efficiency (LEE) using the needle‐shape indium tin oxide (ITO) p‐contact was successfully demonstrated. The needle‐shape ITO p‐contact was naturally grown by using electron‐beam evaporation method under the precisely controlled condition. The structure of ITO p‐contact varied sensitively from the planar‐shape to the needle‐shape with decreasing the deposition temperature and the partial oxygen pressure in the vacuum chamber. We fabricated the p‐side‐up GaN/sapphire LEDs with the needleshape ITO p‐contact and those with the planar‐shape ITO p‐contact using the same LED wafer (peak wavelength: 405 nm). The external quantum efficiency (EQE) of the needle‐shape ITO‐LEDs is 1.5 times larger than that of the planar‐shape ITO‐LEDs (at a forward current of 20 mA). This dramatic increase is attributed to the dramatic increasing of the LEE of the needle‐shape ITO‐LEDs. These results show that the optimizing shape of ITO p‐contact is the key technology to increase the EQE and the LEE of ITO‐LEDs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of grown‐in defects on electron spin polarization in dilute nitride alloys
Authors: Wang X. J. , Buyanova I. A. , Chen W. M. , Hong Y. G. , Tu C. W. 
Published: March 2008

AbstractStrong electron spin polarization in GaNAs epilayers and multiple quantum well structures is observed upon optical orientation at room temperature. The effect is explained in terms of spin dependent recombination (SDR) involving deep paramagnetic defects formed upon N incorporation in GaNAs. Concentration of the corresponding defects is shown to be enhanced during growth at low temperatures but is suppressed by post‐growth annealing. Optically detected magnetic resonance (ODMR) measurements performed in the studied structures reveal two paramagnetic defects participating in carrier recombination. One of them is identified as a complex involving AsGa antisite. Correlation between concentrations of the defects monitored via ODMR and in optical orientation measurements is observed which suggests that the same defects may be involved in both processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carrier dynamics in wide‐band‐gap AlGaN/AlGaN quantum wells
Authors: Tamulaitis G. , Mickevičius J. , Kuokštis E. , Liu K. , Shur M. S. , Zhang J. P. , Gaska R. 
Published: March 2008

AbstractCarrier dynamics in a set of AlGaN/AlGaN multiple quantum wells (MQWs) has been investigated. High‐Al‐content MQWs with well widths varying from 1.65 to 5.0 nm and fixed barrier width were grown by metal‐organic chemical vapor deposition. Time‐resolved photoluminescence (PL) and light‐induced transient grating technique were used to study transient processes in the samples. An observed increase in carrier lifetime with decreasing well width was explained by stronger carrier localization due to the well thickness fluctuations, which prevent the migration of carriers to nonradiative recombination centers. The initial PL decay was shown to be influenced by the screening of the built‐in electric field, which spatially separates electrons and holes. The influence of screening on the PL decay becomes stronger in broader quantum wells and with increasing excitation power density up to the saturation caused by the complete screening of the built‐in electric field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupling of ion‐molecule reactions with liquid chromatography on a quadrupole ion trap mass spectrometer
Authors: Pyatkivskyy Yuriy , Ryzhov Victor 
Published: March 2008

AbstractWe report for the first time a coupling of gas‐phase ion‐molecule reactions with chromatographic separations on a quadrupole ion trap mass spectrometer. The interface was accomplished by using a pulsed valve for the introduction of a volatile neutral into the ion trap. The pulsed valve controller is synchronized with the mass spectrometer software. The setup requires some minor modifications to the vacuum system of the commercial quadrupole ion trap but most of the modifications are external to the mass spectrometer. Two applications of this interface are described: differentiation between two phosphoglucose positional isomers and detection of a phosphopeptide in a peptide mixture. Both applications are using the reactivity of trimethoxyborate towards a phosphate moiety in the negative ion mode. The detection of phosphopeptides hinges on our findings that non‐phosphorylated peptide anions do not react with trimethoxyborate. This LC/MS detection can be easily visualized in terms of selected reaction monitoring. Copyright © 2008 John Wiley & Sons, Ltd.
Mindfulness groups in palliative care: a pilot qualitative study
Authors: Chadwick Paul , Newell Tracey , Skinner Chas 
Published: March 2008

AbstractMindfulness‐based interventions have been shown to have benefits across a diverse range of physical and mental health problems. The present qualitative study explores the experience of individuals diagnosed with a terminal cancer who attended either of two six‐week mindfulness groups. Five people participated. There was a rich diversity in participants' responses. Participants reported finding mindfulness practice beneficial in a range of ways, as well as valuing the social context of the group and the wider hospice setting. Participants also described forming a meta‐understanding of mindfulness practice, which was informed by the experience of others in the group as well as their own, and this understanding illuminated the degree to which people found mindfulness beneficial. In conclusion, the study raises some themes and issues around mindfulness in palliative care which might enrich future practice and research. Copyright © 2008 John Wiley & Sons, Ltd.
Synthese, Struktur und EPR‐Untersuchungen von binuklearen Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))‐Komplexen des CuII, NiII, ZnII, CdII und PdII
Authors: Rodenstein Axel , Griebel Jan , Richter Rainer , Kirmse Reinhard 
Published: March 2008

AbstractSynthesis, Structure and EPR Investigations of binuclear Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato)) Complexes of CuII, NiII, ZnII, CdII and PdIIThe synthesis of binuclear CuII‐, NiII‐, ZnII‐, CdII‐ and PdII‐complexes of the quadridentate ligand N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and the crystal structures of the CuII‐ and NiII‐complexes are reported. The CuII‐complex crystallizes in two polymorphic modifications: triclinic, $P{\bar 1}$ (Z = 1) and monoclinic, P21/c (Z = 2). The NiII‐complex was found to be isostructural with the triclinic modification of the copper complex. The also prepared PdII‐, ZnII‐ and CdII‐complexes could not be characterized by X‐ray analysis. However, EPR studies of diamagnetically diluted CuII/PdII‐ and CuII/ZnII‐powders show axially‐symmetric g and ACu tensors suggesting a nearly planar co‐ordination within the binuclear host complexes. Diamagnetically diluted CuII/CdII powder samples could not be prepared. In the EPR spectra of the pure binuclear CuII‐complex exchange‐coupled CuII‐CuII pairs were observed. According to the large CuII‐CuII distance of about 7,50Å a small fine structure parameter D = 26·10−4 cm−1 is observed; T‐dependent EPR measurements down to 5 K reveal small antiferromagnetic interactions for the CuII‐CuII dimer. Besides of the dimer in the EPR spectra the signals of a mononuclear CuII species are observed whose concentration is T‐dependent. This observation can be explained assuming an equilibrium between the binuclear CuII‐complex (CuII‐CuII pairs) and oligomeric complexes with “isolated” CuII ions.
Darstellung und Kristallstruktur der Phasen Li26Na58Ba38Ex (E = N, H; x = 0 – 1)
Authors: Smetana Volodymyr , Babizhetskyy Volodymyr , Vajenine Grigori V. , Simon Arndt 
Published: March 2008

AbstractPreparation and Crystal Structures of Li26Na58Ba38Ex Phases (E = N, H; x = 0 – 1)Li26Na58Ba38Ex (E = N, H; x = 0–1) were prepared as a majority phase by the reactions of the metals with Ba(N3)2 or BaH2 at 250 °C for five days. According to single crystal and powder X‐ray diffraction investigation, all compounds are cubic, space group $F{\bar 4}{\rm 3}m$ with the unit cell parameter a ranging from 27.335(2) (x = 0) to 27.554(3) (x = 1, E = N, H) Å and Z = 4. This compound series can be described as a filled variant of Li13Na29Ba19, in which nitrogen or hydrogen atoms are found in the centre of Li26 clusters in tetrahedral environment. Li26Na58Ba38Ex represents a new group of metal‐rich compounds extending the growing family of subnitrides.
Structural Investigations and Thermal Behavior of (NH4)[Cr(C2O4)2]·2H2O
Authors: Kahlenberg V. , Wertl W. , Kremenovic A. , Schuster P. , Schottenberger H. 
Published: March 2008

AbstractSingle crystals of ammonium chromium(III) dioxalate dihydrate (or ammonium diaquo bis(μ‐oxalato)chromate(III)) have been obtained from aqueous solution of oxalic acid and ammonium dichromate. A pale violet crystal of good optical quality was used for the structure determination at −100(2) and 25(2) °C, respectively. The basic crystallographic data for the low temperature data set are as follows: monoclinic, space group C2/m, a = 6.597(2) Å, b = 7.301(2) Å, c = 9.983(3) Å, β = 92.32(2)°, V = 480.5(2) Å3. The structure was solved by direct methods and refined (using anisotropic displacement parameters for all non‐hydrogen atoms) to a final residual of R1 = 0.032 for 503 independent observed reflections (I>2σ(I)). The compound is isotypic with the corresponding rubidium salt. The structure is built up from alternating layers parallel to (001) containing (NH4)+ ions or Cr(C2O4)2(H2O)2 octahedra, respectively. The corners of the octahedra consist of four O atoms from two oxalate groups and two additional water molecules. The ammonium cations (occupying Wyckoff‐site 2a) are disordered among two possible orientations. They provide linkage between different octahedral layers by hydrogen bridging. The water molecules in turn form hydrogen bridges with adjacent octahedra within the same layer. Further structural characterization included infrared spectroscopy. According to DTA/TG experiments the present compound shows several thermal processes in the range between room temperature and 900 °C.
Crystal Structure and Disorder Phenomena of the Adduct of Neutral C60 and the Ionic Gold Complex (Ptol3)2AuNO3
Authors: Schulz‐Dobrick Martin , Jansen Martin 
Published: March 2008

AbstractThe adduct C60·(Ptol3)2AuNO3 has been crystallized from toluene solutions of C60 and (Ptol3)2AuNO3 as violet, trigonal plate‐shaped crystals. The compound was studied by single‐crystal x‐ray diffraction ($P{\bar 3}{\rm 1}c$, a = 1278.17(3), c = 2282.92(6) pm). The gold complex is dissociated into [(Ptol3)2Au]+ cations, which encapsulate the neutral C60 molecules, and nitrate anions. The intermolecular interactions between the fullerene molecules and the gold complex cations and the resulting disorder is investigated. The crystal structure of C60·(Ptol3)2AuNO3 is providing an instructive example, demonstrating that symmetry‐matching is not always sufficient for avoiding disorder.
Synthesis and X‐ray Structures of the Polycyclic Dimers {[PhB(μ‐NtBu)2AsN(tBu)H]LiI}2 and [PhB(μ‐NtBu)2AsN(tBu)Li]2
Authors: Konu Jari , Chivers Tristram 
Published: March 2008

AbstractThe metathesis of [PhB(μ‐NtBu)2]AsCl and tBuN(H)Li in 1:1 molar ratio in diethyl ether produced the amido derivative [PhB(μ‐NtBu)2AsN(tBu)H] (1) in good yield. The lithiation of 1 with one equivalent of nBuLi afforded the lithium salt [PhB(μ‐NtBu)2AsN(tBu)Li] (2a). Both 1 and 2a were characterized by multinuclear NMR spectroscopy. The crystal structure of 2a is comprised of a U‐shaped, centrosymmetric dimer in which the monomeric [PhB(μ‐NtBu)2AsN(tBu)]−Li+ units are linked by Li‐N interactions to give a six‐rung ladder. Oxidation of 2a with one‐half equivalent of I2 in diethyl ether resulted in hydrogen abstraction from the solvent to give the dimeric lithium iodide adduct {[PhB(μ‐NtBu)2AsN(tBu)H]LiI}2 (1·LiI) with a central Li2I2 ring.
The First Homoleptic Bis(trifluoromethanesulfonyl)amide Complex of Yttrium: [bmim][Y(Tf2N)4]
Authors: Babai Arash , Mudring Anja‐Verena 
Published: March 2008

Abstract1‐Butyl‐3‐methylimidazolium tetrakis‐(bis(trifluoromethanesulfonyl)amide)yttrium(III), [bmim][Y(Tf2N)4], was obtained from the ionic liquid 1‐butyl‐3‐methylimidazoliumbis(trifluoromethanesulfonyl)amide, [bmim][Tf2N] and yttrium(III)bis(trifluoromethanesulfonyl)amide, Y(Tf2N)3. The crystal structure [monoclinic, C2/c (no. 15), a = 2096.(1), b = 1451.5(1), c = 1608.55(9) pm, β = 109.669(6)°, V = 4608.1(5)·106 pm3, Z = 4, R1 for 3874 symmetry independent reflections with I0>2σ(I0): 0.0438] contains YIII coordinated by four Tf2N‐ligands which all adopt a transoid‐conformation with respect to their –CF3 groups. The oxygen coordination polyhedron around YIII can be best described as a trigonal dodecahedron.One 1‐butyl‐3‐methylimidazolium cation compensates for the charge of the complex [Y(Tf2N)4]− anion.
Synthesis and Crystal Structures of Dinuclear Palladium and Mononuclear Nickel Complexes of Macrocyclic N8S4 Ligands
Authors: Lozan Vasile , Kersting Berthold 
Published: March 2008

AbstractThe N8S4 donor ligand L1 has been investigated regarding its capability to support the formation of coordinatively unsaturated Pd2 complexes and its use as a starting material for functionalized N8S4 systems. L1 represents a macrotricyclic ligand comprising four 4‐tert‐butyl‐2,6‐bis(aminomethyl)thiophenolate units, whose N and S atoms are linked by ethylene units. Treatment of L1 with [Pd(NCMe)2Cl2] produced the dinuclear complex [Pd2Cl2(H2L1)]4+, which was isolated as its pale‐yellow perchlorate salt [Pd2Cl2(H2L1)](ClO4)4 (H21) and characterized by elemental analysis, IR, NMR and MS spectroscopy and X‐ray crystallography. The structure shows two planar PdN2SCl units which are located in the central 24‐membered ring of L1. Reaction of L1 with CH2O/HCO2H under Eschweiler‐Clarke conditions followed by deprotection with sodium in liquid ammonia furnished the permethylated octaamine‐tetrathiophenol H4L4. The identity of H4L4 was ascertained by an X‐ray crystal structure determination of one of its metal complexes.
Complexes of N‐Thiophosphorylthiourea tBuNHC(S)NHP(S)(OiPr)2 with Zinc(II), Cadmium(II), Nickel(II), and Cobalt(II) Cations
Authors: Safin Damir A. , Sokolov Felix D. , Gimadiev Timur R. , Brusko Vasiliy V. , Babashkina Maria G. , Chubukaeva Dinara R. , Krivolapov Dmitriy B. , Litvinov Igor A. 
Published: March 2008

AbstractReaction of the potassium salt of N‐thiophosphorylthiourea tBuNHC(S)NHP(S)(OiPr)2 (HL) with ZnII, CdII, NiII and CoII in aqueous EtOH leads to complexes of common formula M(L‐S,S′)2 (ML2). Complexes were investigated by IR, UV‐Vis, 1H and 31P{1H} NMR spectroscopy and microanalysis The structure of complex NiL2 was investigated by single crystal X‐ray diffraction analysis. The nickel(II) ion has a squre‐planar environment, S4, with two anionic ligands involving 1,5‐S,S′‐coordination mode. The ligands are bound in a trans configuration.
Chelate Complexes of the Pyrid‐2‐yl Analogue of Tetracyclone
Authors: Siemeling Ulrich , Klemann Thorsten , Bruhn Clemens , Neumüller Bernhard , Dehnicke Kurt 
Published: March 2008

AbstractThe tetradentate ligand 2,3,4,5‐tetra(pyrid‐2‐yl)cyclopent‐2,4‐dien‐1‐one (3) was prepared and used for the synthesis of the dinuclear chelates [μ‐(3)(MX2)2] (MX2 = BeCl2, ZnCl2, ZnBr2, HgCl2, HgBr2); the closely related BeCl2 chelate of the bidentate ligand 2,5‐diphenyl‐3,4‐di(pyrid‐2‐yl)cyclopent‐2,4‐dien‐1‐one (1) was also prepared. The structures of these compounds were determined by X‐ray crystallography and compared to those of the corresponding unchelated analogues [(py)2MX2] (py = pyridine). Aggregation to polymeric chains by chloro‐bridging was observed for [μ‐(3)(HgCl2)2] in the crystal.