bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure and Phase Composition of Sputter-Deposited Zirconia-Yttria Films
Authors: Knoll R.W. , Bradley E.R. 
Published: March 2011

ABSTRACTThin ZrO2 -Y2 O3 coatings ranging in composition from 3 to 15 mole % Y2 O3 were produced by rf sputter deposition. This composition range spanned the region on the equilibrium ZrO2 -Y2O3 phase diagram corresponding to partially stabilized zirconia (a mixture of tetragonal ZrO2 and cubic solid solution). Microstructural characteristics and crystalline phase composition of as-deposited and heat treated films (1100°C and 1500°C) were determined by transmission electron microscopy (TEM) and by x-ray diffraction (XRD). Effects of substrate bias (0 ∼ 250 volts), which induced ion bombardment of the film during growth, were also studied. The as-deposited ZrO2-Y2O3 films were single phase over the composition range studied, and XRD data indicated considerable local atomic disorder in the lattice. Films produced at low bias contained intergranular voids, pronounced columnar growth, and porosity between columns. At high bias, the microstructure was denser, and films contained high compressive stress. After heat treatment, all deposits remained single phase, therefore a microstructure and precipitate distribution characteristic of toughened, partially stabilized zirconia appears to be difficult to achieve in vapor deposited zirconia coatings.
Non-Equilibrium Modeling and Dissipative Structures in Solid Material - Plasma Interactions
Authors: Khait Yu.L. 
Published: March 2011

ABSTRACTTopics discussed: (a) The dissipative structure (DS) composed of the plasma bulk (PB), near-to-surface plasma layer (PL), surface and the adjacent material layer (ML) coupled by mass, electric charge, etc. fluxes and applications to plasma deposition. (b) The transient local dissipative structure (TLDS) formed by a single plasma ion impinging on the surface and associated with sputtering, etc.
A Mass Spectrometric System for the Study of Transient Plasma Species in Thin Film Deposition
Authors: Johnson N.P. , Webb A.P. , Fabian D.J. 
Published: March 2011

ABSTRACTA system is described for mass spectrometric detection of transient gaseous species involved in reactive plasma deposition of materials. The equipment comprises a three stage differentially pumped UHV quadrupole mass spectrometer chamber, which permits modulated molecular beam sampling over a short path-length, direct from the plasma at 0.1–1.0 torr pressure. Operation of the system and optimum conditions for maximum signal-detection are detailed, and preliminary results for species formed in a silane-argon high-power rf discharge are reported. Spectra mostly agree with those obtained by Turban and Catherine using a lower power rf plasma, although some evidence is observed for the formation of increased SiH species at higher power.
Plasmas in Extractive Metallurgy
Authors: Gauvin W. H. , Choi H. K. 
Published: March 2011

ABSTRACTIt is becoming apparent that plasma technology will revolutionize certain of the conventional operations of extractive metallurgy. The use of plasma arcs in the iron and steel industry is already being demonstrated at powers up to 100 MW and these development will be briefly reviewed. In this connection, the advantages of plasma furnaces over electric furnaces are beginning to be well documented.It is, however, in the area of the production of the refractory metals, such as molybdenum, zirconium, titanium, niobium, tungsten, tantalum, chromium and vanadium, that plasma technology offers unique opportunities as a result of advances in the design of transferred arc reactors. The work of the authors in this particular field will be described as well as other recent industrial developments.
Correlation of Electrical, Structural, and Optical Properties of Erbium In Silicon
Authors: Benton J. L. , Eaglesham D. J. , Almonte M. , Citrin P. H. , Marcus M. A. , Adler D. L. , Jacobson D. C. , Poate J. M. 
Published: March 2011

ABSTRACTAn understanding of the electrical, structural, and optical properites of Er in Si is necessary to evaluate this system as an opto-electronic material. Extended x-ray absorption fine structure, EXAFS, measurements of Er-implanted Si show that the optically active impurity complex is Er surrounded by an O cage of 6 atoms. The Er photoluminescence intensity is a square root function of excitation power, while the free exciton intensity increases linearly. The square root dependence of the 1.54μm-intensity is independent of measurement temperature and independent of co-implanted species. Ion-implantation of Er in Si introduces donor activity, but spreading resistance carrier concentration profiles indicate that these donors do not effect the optical activity of the Er.
Er Luminescence in Si: A Critical Balance between Optical Activity and Pumping Efficiency
Authors: Coffa S. , Priolo F. , Franzó G. , Bellani V. , Carnera A. , Spinella C. 
Published: March 2011

ABSTRACTThe several processes required to achieve Er luminescence in Si are investigated. In particular, the role of Er - O interactions to obtain the incorporation of high Er concentrations, electrically and optically active, in crystalline Si is investigated. It is found that a large enhancement in the electrical activation of Er (up to three orders of magnitude) is obtained by co-implanting Er with O at 573 K or at 77 K. However, the introduction of high concentrations of active Er in Si is not sufficient to obtain a large enhancement in the luminescence since an efficient pumping of the optically active sites is also required. The optical efficiency of this sample has been studied by photoluminescence. It is seen that an enhancement by a factor of ∼ 5 with respect to literature data is obtained. Moreover studies on the luminescence intensity as a function of the pump power gave important information on the mechanisms underlying Er luminescence in Si and its competing phenomena. These data are presented and discussed.
1.54 μm Photoluminescence of Erbium Implanted Hydrogenated Amorphous Silicon
Authors: Kechouane M. , Beldi N. , Mohammed-Brahim T. , L'Haridon H. , Salvi M. , Gauneau M. , Favennec P.N. 
Published: March 2011

ABSTRACTThe luminescence of erbium implanted in hydrogenated amorphous silicon (a-Si : H) is presented. For the first time an intense and relatively sharp luminescence at 1.54 mm is observed in a-Si : H, using implanted erbium. The Er+ emission intensity strongly depends on the hydrogen film content and on the measurement temperature. A direct correlation between the optical gap energy of the semiconductor and the hydrogen film content is observed.
Electronic Properties and Their Relations to Optical Properties in Rare Earth Doped III-V Semiconductors
Authors: Taguchi Akihito , Takahei Kenichiro , Nakata Jyoji 
Published: March 2011

ABSTRACTWe discuss the energy transfer mechanism between rare-earth 4f-shells and III-V semiconductor hosts. For Yb-doped InP, we have proposed an excitation and relaxation model, which explains experimental results for the electronic and optical properties. The Yb 4f-shell is excited by a recombination of an electron and a hole at an electron trap formed by Yb, which is located near the bottom of the conduction band of InP. At high temperatures, the relaxation energy of the Yb 4f-shell is back transferred as a host electron-hole pair, resulting in Yb luminescence quenching. We have found that Er-doped GaAs samples grown by metalorganic chemical vapor deposition contain as much C as Er. Rutherford back scattering and electronic property measurement results suggested that most of the Er atoms form complexes with C atoms, and these complexes are not electrically active. Such samples showed complicated Er 4f-shell luminescence spectra. To obtain a simple Er luminescence spectrum with a high peak intensity, O was intentionally doped with Er. Er-O complexes seemed to be formed in GaAs and these are responsible for simple and strong 4f-shell luminescence.
Mocvd Growth and Properties of Erbium Doped GaAs
Authors: Langer Dietrich W. , Li Yabo , Fang Xiao M. , Coon Victoria 
Published: March 2011

ABSTRACTErbium doped GaAs was grown by metalorganic chemical vapor deposition using a novel liquid precursor: Tris(n-butylcyclopentadienyl)erbium, Er(C4H9C5H4)3. Growth parameter, i.e. temperature, V/III ratio, Er-vapor flow, were investigated. The maximum erbium incorporation in layers with excellent morphology was 1.2× 1019cm−3. The erbium-related photoluminescence intensity and the incorporated concentrations, as measured by secondary ion mass spectrometry, were correlated. Based on a simple model for, the excitation dependence of the emission, the non-radiative Auger-type process was estimated to be nearly five times that of the energy transfer process from bound excitons to the Er3+ ions, which subsequently resulted in the Er-related light emission. Temperature induced quenching of the emission was found to be dominated by transitions with an activation energy of 74meV.
Effects of Ytterbium Addition on Liquid Phase Epitaxial Growth of InGaAs/InP Heterostructures
Authors: Davis A. , Dauplaise H.M. , Lorenzo J.P. , Ramseyer G.O. , Horrigan J. A. 
Published: March 2011

ABSTRACTWe have investigated the effects of Yb addition to melts used for the growth of InGaAs/InP heterostructures by liquid phase epitaxy. Our results indicate that impurities in the Yb play an important role in determining the changes in electrical properties observed in the epilayers after Yb treatment of the melt. We have examined samples using double-crystal x-ray diffractometry, photoluminescence, Hall/van der Pauw measurements, and secondary-ion mass spectroscopy. After Yb treatment, the residual carrier concentrations of the epilayers were reduced by more than one order of magnitude and the samples luminesced more strongly; while the lattice matching and crystal quality of the epilayers were not measurably affected by the Yb. There was a smaller-thanexpected ncrease in the 77K mobility and a marked increase in the compensation ratio of the epilayers grown after the addition of Yb to the melt. We believe the Yb is both acting as a scavenging agent in the melt, combining with impurities that otherwise would have been incorporated in the epilayers, and introducing deep level impurities of its own, which are incorporated into the grown layers.
Optical Activity of Yb3+ in MeV Ion-Implanted InP.
Authors: Uekusa S. , Majima A. , Katsumata H. , Noyori Y. , Kumagai M. 
Published: March 2011

ABSTRACTFor the evaluation of an implanted layer, photoluminescence (PL) and photoluminescence excitation (PLE) measurements, which are nondestructive and sensitive methods for identifying impurities and defects, were performed. Yb3+ -related sharp luminescence was observed at a wavelength of 1002nm, due to the transitions which occurred between the spin-orbit levels 2F5/2→2F7/2 of Yb3+ (4f13). Most efficient luminescence of Yb3+ was achieved at an excitation wavelength of around 880nm. The luminescence intensity of this peak (Yb3+) decreased with an increase in annealing temperature. Since the peak has not been observed for good samples in crystallinity, it may indicate that new, efficient energy transfer processes to rare-earth ions occur through the defect energy level. Especially, for the sample annealed at 600°C, Yb-related luminescence intensity excited by the photon energy below the band gap is about 3 times larger than that of excited by the photon energy above the band gap.
Tm Doping of Lead Telluride
Authors: Ryabova Ludmila I. , Tamm Marina E. 
Published: March 2011

ABSTRACTDoping with the rare earth elements is widely used for the improvement of parameters of the PbTe-based lasers. It has been found that Tm is a donor in PbTe, and the solubility of TmTe in PbTe does not exceed 7 - 8 mol.%. Electron concentration in obtained PbTe(Tm) crystals reaches 4.1020 cm-3 and depends on Tm content and on deviation from stoichiometry. The analysis of the magnetoresistance oscillation picture shows no variation of the energy spectrum parameters for Tm contents less than I at.%. The g-factor does not change as well. This may be due to a rather small exchange interaction between Tm atom, which is magnetic in both +2 and +3 valence states, and band electrons. The experimental data for PbTe(Tm) are compared with the properties of semimagnetic PbTe(Cr) with quite the same electron consentration value.
Excitation and De-Excitation Mechanisms of Rare-Earth Ions in III-V Compounds: Optically Detected Microwave-Induced Impact Ionization of Yb Dopant in Inp
Authors: Gregorkiewicz T. , Liesertr B.J. Heijmink , Tsimperidis I. , de Maat-Gersdorf I. , Ammerlaan C.A.J. , Godlewski M. , Scholz F. 
Published: March 2011

ABSTRACTThe excitation mechanisms of rare-earth dopants in III-V semiconductors are being reviewed. The discussion is focused on ytterbium-doped InP crystals for which a particularly large amount of experimental data has been gathered. Here, the results obtained recently by optically detected microwave-induced impact ionization are being examined in detail. On the basis of the experimental findings it is argued that the intrashell luminescence is excited by an intermediate state involving binding of an exciton. Direct evidence for the existence of such a state, of pseudoacceptor type, will be given. The nonradiative recombination channel responsible for the fast decay of Yb luminescence will also be discussed and, for the first time, evidence for an Auger process will be presented. It will also be shown that the nonradiative channel may be effectively blocked by impact ionization of a participating carrier.
Luminescence Properties of Yb-Doped Inp
Authors: Lozykowski H. J. , Alshawa A. K. , Pomrenke G. , Brown I. 
Published: March 2011

ABSTRACTThe photoluminescence, time resolved spectra and kinetics of Yb implanted InP samples are studied under pulsed and CW excitations (above and below band-gap) at different temperatures and excitation intensity. The photoluminescence intensity and decay time as a function of temperature is explained by a proposed new quenching mechanism involving Fe ion. The rise and decay times depend on excitation intensity. The above experimental facts was explained using the kinetics model developed by H.J. Lozykowski [2]. The numerically simulated luminescence rise and decay times show a good quantitative agreement with experiment, over a wide range of generation rates. The electric field InP:Yb photoluminescence quenching was investigated and reported for the first time.
Excitation and Relaxation Processes of Impact Excitation Emission of Er3+ Ions in InP
Authors: Kimura T. , Ishida H. , Yugo S. , Saito R. , Isshiki H. , Ikoma T. 
Published: March 2011

ABSTRACTTime-resolved excitation and relaxation processes of the impact excitation emission (EL) at 1.54μm of Er3+ ions doped in InP were investigated in the temperature range from 77K to 330K. The decay process was almost exponential in all the measured temperature range and showed little thermal quenching. The decay time of 2ms at 77K decreased only to tms at 330K. This result contrasted with the large thermal quenching and nonexponential characteristics of the photoluminescence (PL) time decay at higher temperatures, suggesting different Er3+ centers excited between EL and PL. A two-emission-center model is proposed and the different behaviors of thermal quenching and time decay between EL and PL emissions are consistently explained.
Impact excitation of Er-doped GaAs and the rare-earth sites in III-V compound semiconductors
Authors: Chang S. J. , Takahei K. , Nakata J. , Su Y. K. 
Published: March 2011

ABSTRACTWe report the first study of impact excitation of Er ions in GaAs. The MOCVDgrown, p+-n structured EL devices were fabricated by growing, at different temperatures, GaAs:Er layers on top of the n+ GaAs substrates. P+ layers were made by Zn diffusion from the top surfaces. When we forward biased these diodes, their EL spectra were similar to their respective PL spectra for each sample but different from each other's. However, when we reverse biased these diodes, EL spectra obtained from all samples are the same, which were different from their PL spectra. These results indicate that the Er center(s) excited by direct impact is different from the Er center(s) excited through electron-hole recombination and subsequent energy transfer. By using RBS channeling, we found that most of the Er ions, in our MOCVD-grown GaAs:Er samples, occupy a displaced tetrahedral interstitial site. From these PL, EL and RBS results, we conclude that only a small amount of Er ions emit luminescence when they are indirectly excited through energy transfer.
Movpe of Rare Earth Doped III-V Semiconductors
Authors: Scholz F. , Weber J. , Pressel K. , Dörnen A. 
Published: March 2011

ABSTRACTDifferent III-V compound semiconductors have been doped with the rare earth (RE) elements Yb, Er, and Tm using atmospheric pressure metalorganic vapor phase epitaxy. Best results have been obtained using the novel metalorganic compounds tris-isopropyl-cyclopentadienyl-RE as precursors which have an acceptable vapor pressure and can be used as liquids at bubbler temperatures of 60°-90°C. Only Yb has been found to occupy a regular lattice site in InP, whereas the other RE show complex optical spectra because of their incorporation in form of different centers and clusters.
Rare-Earths Applications in III-V Crystal Growth Technology.
Authors: Zakharenkov Leo 
Published: March 2011

The problem of manufacturing high purity semiconductor materials with super high electron mobility is among important, though technologically difficult ones.Traditional with regard to III-V compounds this problem has been solved using the following technique- the choice of alternative crucible material- the application of high purity initial materials- oxygen doping for shallow donors removal- isoelectronic doping (e.g. bismuth)We can also mention other attractive directions in this sphere of activity, such as secondary methods of influence upon the crystals grown - heat treatment and purification by radiation methods, the latter ones still wanting being explored.From the late 70's we have been carrying out the investigations of the rare-earths (RE) influence upon the electrical characteristics of InP, and later - of GaAs.In this work submitted are the results of comprehensive investigation of RE applications in bulk III-V crystal growth technology with the aim of purification and heavy doping of the crystals.
Erbium Doped Gallium Arsenide a Self-Organising Low Dimensional System
Authors: Peaker A.R. , Efeoglu H. , Langer J.M. , Wright A.C. , Poole I. , Singer K.E. 
Published: March 2011

ABSTRACTThe growth of erbium doped gallium arsenide by MBE at normal substrate temperatures (∼580°C) is constrained by a solubility limit of 8×1017 cm−3. This is much less than is desirable for optical emitters using the forbidden 4f transitions of Er3+ to produce radiation at 1.54μm. We have developed an MBE technique where it is possible to produce spherical mesoscopic precipitates containing erbium as a matrix element within the gallium arsenide. Structural and analytical studies indicate that the precipitate is cubic (rock salt) erbium arsenide. The physical size of the precipitates is self limiting as a result of surface migration occurring during MBE growth. By adjusting the growth conditions it is possible to produce an array of uniform erbium arsenide quantum dots of a size chosen from the range 10-20Å. The dot density can be varied by changing the erbium flux.
EuTe/PbTe Superlattices: Mbe Growth and Optical Characterization
Authors: Springholz G. , Yuan Shu , Bauer G. , Kriechbaum M. , Krenn H. 
Published: March 2011

ABSTRACTThe heteroepitaxial growth of EuTe on PbTe (111) by molecular beam epitaxy (MBE) was investigated using in situ reflection high energy electron diffraction (RHEED). As a function of substrate temperature and Te2 flux rate, the resulting EuTe (111) surfaces exhibit several different surface reconstructions corresponding to Te-stabilized or Eu-stabilized surfaces. The Eustabilized surface shows a (2√3 × 2√3)R30° surface reconstruction. Because of the strain induced tendency for 3D islanding, only in a narrow window of MBE growth parameters perfect 2D layer-by-layer heteroepitaxial growth exists. Using such optimized MBE growth conditions, we have fabricated a series of PbTe/EuTe superlattices. In such superlattices the wide band gap EuTe layers act as barriers and the narrow band gap PbTe as quantum wells. The superlattices were investigated by high resolution x-ray diffraction, showing their high structural perfection. Modulated low temperature Fourier transform infrared reflection measurements were performed in order to determine the confined energy levels in the PbTe quantum wells. The measurements indicate that mini-subbands are formed in the PbTe quantum wells with a mini-band width of 22 meV in agreement with envelope function calculations.
Electron Structure and Mechanism of Excitation of the Rare-Earth ions in the III-V Semiconductors
Authors: Masterov Vadim F. 
Published: March 2011

ABSTRACTThe review of results of KPR, ODMR, RBS and PL investigations of the III-V semiconductors doped with rare-earth elements is represented. The possible sites of RE related centers in hostare discussed. The possible mechanism of excitation of intrashell f-f transitions is considered. The simple theoretical model of the substitutional RE center in a binary semiconductors is discussed.
The Theory of Rare-Earth Impurities in Semiconductors
Authors: Lannoo Michel , Delerue C. 
Published: March 2011

ABSTRACTThe chemical trends of rare-earth impurities in semiconductors are analyzed on the basis of a selfconsistent tight-binding Green's function technique. The 4f states are treated as a frozen core and we get essentially no 5d derived states in the gap. We calculate the 4f ionization levels in the solid and conclude that the stable state is mostly 3+. We then describe the results of a LDA calculation for Er in silicon which we find to be stable in the interstitial position. Finally we consider in some detail the case of Yb in InP where we discusss the possible origin of the shallow gap levels and the mechanisms for luminescence excitation and quenching.
Kinetics of the Luminescence of Isoelectronic Rare-Earth Ions In III-V Semiconductors
Authors: Lozykowski H.J. 
Published: March 2011

ABSTRACTIn this work we have developed a model for the kinetics of the energy transfer from the host lattice to the localized core excited states of rare earth isoelectronic structured traps (REI-trap). We have derive a set of differential equations for semi-insulating semiconductor governing the kinetics of rare earth luminescence. The numerically simulated rise and decay times of luminescence show a good quantitative agreement with the experimental data obtained for InP:Yb, over a wide range of generation rates.