Home About us Contact
|
Home About us Contact | ||
|
|
||
Semiconductor Materials (semiconductor + material)
Selected Abstracts6th International Workshop on Expert Evaluation & Control of Compound Semiconductor Materials & TechnologiesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003Bálint P The EXMATEC workshops are a series of biannial conferences with the aim to bring together research and development specialists involved in compound semiconductor material physics, chemistry, process technology, characterization and device fabrication. EXMATEC 2002 is the continuation of successful meetings, previously held in Lyon, Parma, Freiburg, Cardiff and Heraklion. The central topics were development, improvement and application of new and advanced methods in the fabrication and evaluation of compound semiconductor materials and structures to develop understanding of the interrelationship between structural, electrical and other material properties and device characteristics, such as performance, reliability, reproducibility, lifetime, yield, etc. The conference topics apply to all compound semiconductor materials (III,V, II,VI, IV,IV, II,IV,V2), related structures and processing steps (from substrate and epitaxial growth to complete devices) and cover instrumentation and characterization issues. The full Proceedings of EXMATEC 2002 are published in the second issue of the new journal series physica status solidi , conferences Vol. 0, No. 2 (2003). As one representative example of the topics presented at this conference, the cover picture of the present issue issue of phys. stat. sol. (a) shows the band scheme of a typical GaInAs/AlInAs superlattice quantum cascade laser, taken from the invited paper by Razeghi and Slivken [1]. [source] Application of the TLM technique to integrated optic component modellingINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 2 2001O. Jacquin The TLM algorithm is of high interest to simulate new integrated optical devices as a ,photonic band gap' (PBG) structures. These components are realized with semiconductor material and constituted by a set of abrupt optical discontinuities. The electromagnetic behaviour of these structures does not allow the use of usual simulation methods of integrated optics. Indeed, their validity conditions are not satisfied. Then, we have to use unusual simulation method for integrated optics as TLM software which allows the visualization and understanding of the behaviour of electromagnetic field in the PBG structures. In this paper, the simulation results of different optical devices made from the TLM method are presented. Copyright © 2001 John Wiley & Sons, Ltd. [source] ta-C/Si heterojunction diodes with apparently giant ideality factorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010Marc Brötzmann Abstract A common feature of many wide band gap heterojunction diodes is an unexplained large ideality factor n > 2. In this context we investigate the diode characteristics of heterojunction diodes consisting of a crystalline semiconductor material such as Si covered with a thin semiconducting film of amorphous or disordered material. As thin amorphous film we use tetrahedral amorphous carbon (ta-C). These heterojunctions exhibit a pronounced rectifying behavior, low saturation current and low parasitic currents. Moreover, we observe an apparently giant ideality factor reaching values of n > 75. As a consequence, the turn on voltage is around 3 , 10 V and the I-V curves can be measured for bias up to 40 V without reaching saturation or electrical breakdown. We present a quantitative model for the unusual diode characteristics of these Metal , Amorphous Semiconductor , Semiconductor diodes (MASS-diodes). We demonstrate that the I-V characteristics of the heterojunctions are well described by a serial arrangement of an ideal Schottky-diode, a Frenkel-Poole type resistance and an Ohmic contact resistance, emulating a p-n- or Schottky diode characteristic with giant ideality factor and referred to as the FPID-model. We propose that heterojunctions exhibiting apparently large ideality factors n , 2 may possess an interfacial disordered or amorphous layer with Frenkel-Poole conduction properties. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A theoretical investigation of carrier and optical mode confinement in GaInNAs QWs on GaAs and InP substratesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007B. Gönül Abstract Both carrier and optical mode confinements are the basic ingredients while designing the semiconductor quantum well lasers. The former strongly depends on the band offsets of the heterostructure and the latter is mainly associated with the difference in the refractive index between the wave guiding core and the cladding layers. It is known that refractive index strongly depends on the direct band gap of the semiconductor material and the band gap of the III-N-V semiconductor layer can be engineered by means of adding nitrogen into InGaAs. We investigate, in this work, the refractive indices and the corresponding optical confinement factors of the proposed III-N-V laser material systems on GaAs and InP substrates. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis of phase-pure SnS particles employing dithiocarbamate organotin(IV) complexes as single source precursors in thermal decomposition experimentsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2010D. C. Menezes Abstract Preparation of tin(II) sulfide, semiconductor material, has been accomplished by thermal decomposition of easily prepared organotin dithiocarbamate complexes: [Sn{S2CNEt2}2Ph2] (1), [Sn{S2CNEt2}Ph3] (2), [Sn{S2CNEt2}3Ph] (3) and [Sn{S2CN(C4H8)}2Bu2] (4). Phase-pure tin(II) sulfide has been obtained by pyrolysis of these precursors at 350 °C in N2. Thermogravimetric analysis, X-ray powder diffraction, scanning electron microscopy, X-ray electron probe microanalysis and 119Sn Mössbauer spectroscopy revealed that the complexes decompose in a single and sharp step (1 and 2), or in pseudo-single stage (3 and 4), to produce SnS. We have also measured the bandgap energies of the residues using electronic spectroscopy in the solid state and the result relates well to that in the literature for SnS, 1.3 eV. A decomposition mechanism was also proposed for each complex based on electrospray ionization tandem mass spectrometric results. The synthetic method used in this work might be useful for the preparation of pure SnS on a large scale. Copyright © 2010 John Wiley & Sons, Ltd. [source] Development of an oxide semiconductor thick film gas sensor for the detection of total volatile organic compoundsELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 10 2010Masahiro Kadosaki Abstract Since the amendment of the Building Standards Law in 2003, the installation of ventilators is compulsory in newly built houses, because many persons suffer from indoor air pollution caused by volatile organic compounds (VOCs). The goal of this research is to develop a gas sensor that can monitor the total VOC (TVOC) gases indoors and then to control the ventilator efficiently using the sensor. In order to develop a sensor that detects TVOC, the responses of four oxide semiconductor materials to 37 different VOC gases were studied. These materials showed small responses to halogenated and aliphatic hydrocarbon gases. As a result of improving the response to these gases, among four metal oxides examined, SnO2 and WO3 showed high sensitivities by the addition of Pd and Pt. The sensing properties of SnO2 for halogenated hydrocarbon gases were greatly improved by the addition of 0.5 wt% Pd. The sensing properties of SnO2 for aliphatic hydrocarbon gases were improved by the addition of 0.7 wt% Pt. In addition, a sensor element with the addition of both platinum and palladium, that is, Pt (0.5 wt%)-Pd (0.5 wt%)-SnO2, showed a large response to many of the VOC gases examined. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(10): 34,41, 2010; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10190 [source] Air-Stable n-Type Organic Field-Effect Transistors Based on Carbonyl-Bridged Bithiazole DerivativesADVANCED FUNCTIONAL MATERIALS, Issue 6 2010Yutaka Ie Abstract An electronegative conjugated compound composed of a newly designed carbonyl-bridged bithiazole unit and trifluoroacetyl terminal groups is synthesized as a candidate for air-stable n-type organic field-effect transistor (OFET) materials. Cyclic voltammetry measurements reveal that carbonyl-bridging contributes both to lowering the lowest unoccupied molecular orbital energy level and to stabilizing the anionic species. X-ray crystallographic analysis of the compound shows a planar molecular geometry and a dense molecular packing, which is advantageous to electron transport. Through these appropriate electrochemical properties and structures for n-type semiconductor materials, OFET devices based on this compound show electron mobilities as high as 0.06,cm2 V,1 s,1 with on/off ratios of 106 and threshold voltages of 20,V under vacuum conditions. Furthermore, these devices show the same order of electron mobility under ambient conditions. [source] Integration of a Rib Waveguide Distributed Feedback Structure into a Light-Emitting Polymer Field-Effect TransistorADVANCED FUNCTIONAL MATERIALS, Issue 9 2009Michael C. Gwinner Abstract Ambipolar light-emitting organic field-effect transistors (LEFETs) possess the ability to efficiently emit light due to charge recombination in the channel. Since the emission can be made to occur far from the metal electrodes, the LEFET structure has been proposed as a potential architecture for electrically pumped organic lasers. Here, a rib waveguide distributed feedback structure consisting of tantalum pentoxide (Ta2O5) integrated within the channel of a top gate/bottom contact LEFET based on poly(9,9-dioctylfluorene- alt -benzothiadiazole) (F8BT) is demonstrated. The emitted light is coupled efficiently into the resonant mode of the DFB waveguide when the recombination zone of the LEFET is placed directly above the waveguide ridge. This architecture provides strong mode confinement in two dimensions. Mode simulations are used to optimize the dielectric thickness and gate electrode material. It is shown that electrode absorption losses within the device can be eliminated and that the lasing threshold for optical pumping of the LEFET structure with all electrodes (4.5,µJ cm,2) is as low as that of reference devices without electrodes. These results enable quantitative judgement of the prospects for realizing an electrically pumped organic laser based on ambipolar LEFETs. The proposed device provides a powerful, low-loss architecture for integrating high-performance ambipolar organic semiconductor materials into electrically pumped lasing structures. [source] Probing the Anisotropic Field-Effect Mobility of Solution-Deposited Dicyclohexyl-,-quaterthiophene Single Crystals,ADVANCED FUNCTIONAL MATERIALS, Issue 10 2007Abstract Measuring the anisotropy of the field-effect mobility provides insight into the correlation between molecular packing and charge transport in organic semiconductor materials. Single-crystal field-effect transistors are ideal tools to study intrinsic charge transport because of their high crystalline order and chemical purity. The anisotropy of the field effect mobility in organic single crystals has previously been studied by lamination of macroscopically large single crystals onto device substrates. Here, a technique is presented that allows probing of the mobility anisotropy even though only small crystals are available. Crystals of a soluble oligothiophene derivative are grown in bromobenzene and drop-cast onto substrates containing arrays of bottom-contact gold electrodes. Mobility anisotropy curves are recorded by measuring numerous single crystal transistor devices. Surprisingly, two mobility maxima occur at azimuths corresponding to both axes of the rectangular cyclohexyl-substituted quaterthiophene (CH4T) in-plane unit cell, in contrast to the expected tensorial behavior of the field effect mobility. [source] Charge Transport Physics of Conjugated Polymer Field-Effect TransistorsADVANCED MATERIALS, Issue 34 2010Henning Sirringhaus Abstract Field-effect transistors based on conjugated polymers are being developed for large-area electronic applications on flexible substrates, but they also provide a very useful tool to probe the charge transport physics of these complex materials. In this review we discuss recent progress in polymer semiconductor materials, which have brought the performance and mobility of polymer devices to levels comparable to that of small-molecule organic semiconductors. These new materials have also enabled deeper insight into the charge transport physics of high-mobility polymer semiconductors gained from experiments with high charge carrier concentration and better molecular-scale understanding of the electronic structure at the semiconductor/dielectric interface. [source] Novel ZrInZnO Thin-film Transistor with Excellent StabilityADVANCED MATERIALS, Issue 3 2009Jin-Seong Park Novel ZrInZnO semiconductor materials to resolve transistor instability for active-matrix organic light-emitting diodes are proposed. The ZrInZnO film is preprared using a cosputtering method, and presents a nanocrystal structure embedded in an amorphous matrix. The thin-film transistors fabricated have good electrical performances as well as excellent stability under long-term bias stresses. [source] Overview of polymer micro/nanomanufacturing for biomedical applicationsADVANCES IN POLYMER TECHNOLOGY, Issue 4 2008Allen Y. Yi Abstract Micro/nanotechnology is initiated from the electronics industry. In recent years, it has been extended to micro/nanoelectromechanic system for producing miniature devices based on silicon and semiconductor materials. However, the use of these hard materials alone is inappropriate for many biomedical devices. Soft polymeric materials possess many attractive properties such as high toughness and recyclability. Some possess excellent biocompatibility, are biodegradable, and can provide various biofunctionalities. Proper combinations of micro/nanoelectronics, polymers, and biomolecules can lead to new and affordable medical devices. In this paper, we briefly review several cleanroom and noncleanroom techniques related to micro/nanomanufacturing of polymeric materials. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:188,198, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20134 [source] Hydrogen generation from photoelectrochemical water splitting based on nanomaterialsLASER & PHOTONICS REVIEWS, Issue 4 2010Y. Li Abstract Hydrogen is potentially one of the most attractive and environmentally friendly fuels for energy applications. Safe and efficient generation, storage, and utilization of hydrogen present major challenges in its widespread use. Hydrogen generation from water splitting represents a holy grail in energy science and technology, as water is the most abundant hydrogen source on the Earth. Among different methods, hydrogen generation from photoelectrochemical (PEC) water splitting using semiconductors as photoelectrodes is one of the most scalable and cost-effective approaches. Compared to bulk materials, nanostructured semiconductors offer potential advantages in PEC application due to their large surface area and size-dependent properties, such as increased absorption coefficient, increased band-gap energy, and reduced carrier-scattering rate. This article provides a brief overview of some recent research activities in the area of hydrogen generation from PEC water splitting based on nanostructured semiconductor materials, with a particular emphasis on metal oxides. Both scientific and technical issues are critically analyzed and reviewed. [source] UV emission on a Si substrate: Optical and structural properties of ,-CuCl on Si grown using liquid phase epitaxy techniquesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2009A. Cowley Abstract Considerable research is being carried out in the area of wide band gap semiconductor materials for light emission in the 300,400 nm spectral range. Current materials being used for such devices are typically based on II,VI and III-nitride compounds and variants thereof. However, one of the major obstacles to the successful fabrication of III-N devices is lattice mismatch-induced high dislocation densities for epitaxially grown layers on non-native substrates. ,-CuCl is a direct bandgap material and an ionic wide bandgap I,VII semiconductor with a room temperature free exciton binding energy of ,190 meV (compared to ,25 meV and ,60 meV for GaN and ZnO, respectively) and has a band gap of 3.4 eV (, , 366 nm). The lattice constant of ,-CuCl (0.541 nm) is closely matched to that of Si (0.543 nm). This could, in principle, lead to the development of optoelectronic systems based on CuCl grown on Si. Research towards this end has successfully yielded polycrystalline ,-CuCl on Si(100) and Si(111) using vacuum-based deposition techniques [1]. We report on developments towards achieving single crystal growth of CuCl from solution via Liquid Phase Epitaxy (LPE) based techniques. Work is being carried out using alkali halide flux compounds to depress the liquidus temperature of the CuCl below its solid phase wurtzite-zincblende transition temperature (407 °C [2]) for solution based epitaxy on Si substrates. Initial results show that the resulting KCl flux-driven deposition of CuCl onto the Si substrate has yielded superior photoluminescence (PL) and X-ray excited optical luminescence (XEOL) behavior relative to comparitively observed spectra for GaN or polycrystalline CuCl. This enhancement is believed to be caused by an interaction between the KCl and CuCl material subsequent to the deposition process, perhaps involving a reduction in Cl vacancy distributions in CuCl. This paper presents a detailed discussion of a CuCl LPE growth system as well as the characterization of deposited materials using X-ray diffraction (XRD), room temperature and low temperature PL, and XEOL. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] 6th International Workshop on Expert Evaluation & Control of Compound Semiconductor Materials & TechnologiesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003Bálint P The EXMATEC workshops are a series of biannial conferences with the aim to bring together research and development specialists involved in compound semiconductor material physics, chemistry, process technology, characterization and device fabrication. EXMATEC 2002 is the continuation of successful meetings, previously held in Lyon, Parma, Freiburg, Cardiff and Heraklion. The central topics were development, improvement and application of new and advanced methods in the fabrication and evaluation of compound semiconductor materials and structures to develop understanding of the interrelationship between structural, electrical and other material properties and device characteristics, such as performance, reliability, reproducibility, lifetime, yield, etc. The conference topics apply to all compound semiconductor materials (III,V, II,VI, IV,IV, II,IV,V2), related structures and processing steps (from substrate and epitaxial growth to complete devices) and cover instrumentation and characterization issues. The full Proceedings of EXMATEC 2002 are published in the second issue of the new journal series physica status solidi , conferences Vol. 0, No. 2 (2003). As one representative example of the topics presented at this conference, the cover picture of the present issue issue of phys. stat. sol. (a) shows the band scheme of a typical GaInAs/AlInAs superlattice quantum cascade laser, taken from the invited paper by Razeghi and Slivken [1]. [source] Pulsed electrically detected magnetic resonance in organic semiconductorsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009C. Boehme Abstract Carbon-based materials have an intrinsically weak spin,orbit coupling which imposes spin selection rules on many electronic transitions. The spin degree of freedom of electrons and nuclei can therefore play a crucial role in the electronic and optical properties of these materials. Spin-selection rules can be studied via magnetic resonance techniques such as electron,spin resonance and optically detected magnetic resonance as well as electrically detected magnetic resonance (EDMR). The latter has progressed in recent years to a degree where the observation of coherent spin motion via current detection has become possible, providing experimental access to many new insights into the role that paramagnetic centers play for conductivity and photoconductivity. While mostly applied to inorganic semiconductor materials such as silicon, this new, often called pulsed-(p) EDMR spectroscopy, has much potential for organic (carbon-based) semiconductors. In this study, progress on the development of pEDMR spectroscopy on carbon-based materials is reviewed. Insights into materials properties that can be gained from pEDMR experiments are explained and limitations are discussed. Experimental data on radiative polaron-pair recombination in poly[2-methoxy-5-(20-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) organic light emitting diodes (OLEDs) are shown, revealing that under operating conditions the driving current of the device can be modulated by spin-Rabi nutation of the polaron spin within the charge carrier pairs. From this experimental data it becomes clear that for polaron pairs, the precursor states during exciton formation, exchange interaction is not the predominant influence on the observed pEDMR spectra. [source] VUV-ellipsometry on GaN: Probing conduction band properties by core level excitationsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2005N. Esser Abstract Spectral ellipsometry is a widely used method for analysing optical properties of materials. In particular electronic interband transitions of many semiconductor materials have been intensively studied employing ellipsometry from the near-infrared to the ultra-violet (UV) spectral range. Electronic excitations involving core-levels, on the other hand, have been a domain of synchrotron based X-ray absorption spectroscopy or electron loss spectroscopy. We apply spectral ellipsometry in the vacuum-UV spectral range to study core level excitations in GaN. The results proof that VUV-ellipsometry is a very versatile tool to obtain information on the p-like component of the density of states (DOS) related to the conduction bands of GaN. Excitations of the 3d core level of Ga are shown to be linked to the partial DOS at the Ga site within the lattice (complementary to the information obtained on nitrogen sites by X-ray absorption at the N1s edge). (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Phonon polariton modes in porous III,V semiconductorsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2005K. S. Joseph Wilson Abstract The phonon polariton modes in the bulk porous III,V semiconductor materials like GaP and GaAs are investigated for different porosity values. Their behavior under an external hydrostatic pressure is also studied. The frequencies of the various modes shift to higher values. The model has been extended to the case of self assembled GaP quantum dots (QDOTs) in GaAs matrix. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical, electrical and structural characterization of CuInSe2 thin filmsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2005C. Calderón The present issue of physica status solidi (b) comprises papers presented at the XVII Latin American Symposium on Solid State Physics (SLAFES 2004) in Havana, Cuba, 6,9 December 2004. Further papers from this conference are published in phys. stat. sol. (c) 2, No. 10 (2005). The cover picture refers to the article [1] on polycrystalline CuInSe2 films by Clara Calderón et al. and shows the crystal structure of CuInSe2 (right) and that of the In-rich phase CuIn3Se5 (left) which were used for the simulation and analysis of the X-ray diffraction spectra. Clara Lilia Calderón Triana is teacher at the Solar Cells Laboratory of Universidad Nacional de Colombia in Bogotá where she has been working on solar cells and semiconductor materials since 1995. In particular, she is fabricating thin film solar cells based on CuInSe2 and Cu(In,Ga)Se2. At SLAFES 2004, Clara Calderón received the physica status solidi Young Researcher Award for her second presentation entitled "Study of electrical transport properties of ZnO thin films used as front contact of solar cells" [2] which is published as Editor's Choice of this issue. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Proceedings of the Tenth International Conference on High Pressure Semiconductor Physics (HPSP-X)PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003Ben MurdinArticle first published online: 30 JAN 200 The Tenth International Conference on High Pressure Semiconductor Physics (HPSP-X) was held as a satellite meeting of the International Conference on the Physics of Semiconductors in Guildford from 5 to 8 August 2002. It brought together scientists and engineers who use high pressure to study the science and technology of semiconductors. The HPSP-X conference reviewed the latest issues and developments in the physics of both bulk and low-dimensional semiconductor materials and devices under pressure. It covered all aspects of fundamental and applied high-pressure semiconductor research, including experimental and theoretical investigations under isotropic or anisotropic stress conditions. Topics such as electronic structures, vibrational and optical properties, transport phenomena, defect states, phase transitions, and novel materials or structures are included in this issue. Following the meetings HPSP-VII in Schwäbisch Gmünd, phys. stat. sol. (b) 198, No. 1 (1996); HPSP-VIII in Thessaloniki, phys. stat. sol. (b) 211, No. 1 (1998), and HPSP-IX in Sapporo, phys. stat. sol. (b) 223, No. 1/2 (2001), the proceedings of this successful conference series are published in physica status solidi for the fourth time. [source] Surface plasmon enhanced light emission from semiconductor materialsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008Koichi Okamoto Abstract Surface plasmon (SP) coupling technique was used to enhance light emissions from semiconductor nanocrystals with evaporated metal layers. We found that the SP coupling can increase the internal quantum efficiencies (IQE) of emission from CdSe-based nanocrystals regardless of the initial efficiencies. This suggests that this technique should be much effective for various materials that suffer from low quantum efficiencies. We also obtained 70-fold enhancement of emission from silicon nanocrystals in silicon dioxide. Obtained IQE value is 38%, which is as large as that of a compound semiconductor with direct transition. The SP coupling technique would bring a great improvement to silicon photonics. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Well-width dependence of coupled Bloch-phonon oscillations in biased InGaAs/InAlAs superlatticesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2004Michael Först Abstract The coupling between Bloch oscillations and longitudinal optical (LO) phonons is investigated in ternary In0.53Ga0.47As/In0.52Al0.48As superlattices of different well widths. In femtosecond time-resolved studies, a strong increase of the coherent LO phonon amplitudes is observed when the Bloch oscillations are subsequently tuned into resonance with the different optical phonon modes of the ternary semiconductor materials. In a narrow-well superlattice where electronic minibands are energetically shifted close to the confining barrier potential, the phonon amplitudes are asymmetrically enhanced on the high-frequency edge of the resonance. Here, at high electric fields, field induced tunneling into above-barrier continuum states leads to a rapid dephasing of Bloch oscillations. The associated polarization change provides an additional excitation process for coherent LO phonons. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] 3rd Workshop on Semiconductor Nanodevices and Nanostructured Materials (NanoSemiMat-3)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2004E. F. da Silva Jr. The 3rd Workshop on Semiconductor Nanodevices and Nanostructured Materials (NanoSemiMat-3) took place in Salvador, Bahia, Brazil, 24,27 March 2004. The NanoSemiMat network is part of the Brazilian Initiative on Nanoscience and Nanotechnology (N&N). The papers include the following topics: Photodetectors, Lasers and LEDs, Porous Materials, New Materials, New Technologies, Molecular Technology and Interfaces, Nanostructured Materials and Nanobiotechnology. The presentations reflect theoretical and experimental research on nanostructured semiconductor materials such as III,V and II,VI, Si and SiC based nanodevices, wide gap materials, ceramics, polymers, porous materials, optical and transport properties of low-dimensional structures, magnetic nanostructures and structures under the influence of high fields, spintronics and sensor applications. This issue is devoted to Prof. J. R. Leite, Sao Paulo, former Regional Editor of physica status solidi and Guest Editor in memoriam of the present Proceedings. [source] Preface: phys. stat. sol. (c) 1/S2PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2004E. F. da Silva Jr. The papers in this special issue of physica status solidi (c) are selected manuscripts including diverse research lines presently in development in the ambit of the NanoSemiMat network in Brazil. The 3rd Workshop on Semiconductor Nanodevices and Nanostructured Materials (NanoSemiMat-3) took place in Salvador, Bahia, Brazil, at the Catussaba Resort Hotel, during the period of 24,27 March 2004. The NanoSemiMat network is part of the Brazilian Initiative on Nanoscience and Nanotechnology (N&N), with strategic cooperative research support in this area. The initiative started in 2001, through the formation of four research networks nationwide in different scientific fields associated to NanoScience and Nanotechnology (N&N). The 3rd Workshop on Nanodevices and Nanostructured Materials (NanoSemiMat-3) is an evolution of the two previous meetings which were held in Recife, PE, Brazil and Natal, RN, Brazil in 2002 and 2003, respectively. The meeting comprised 16 invited plenary talks, each 30 minutes long, given by eminent researchers from Brazil, Canada, France, Germany and the United States of America. These invited talks extend through different topics of N&N associated to Nanodevices and Nanostructured Materials: Photodetectors, Lasers and LEDs, Porous Materials, New Materials, and New Technologies, among others. There were short talks presented by representatives of the other N&N networks in Brazil dealing with Molecular Technology and Interfaces, Nanostructured Materials and Nanobiotechnology. Also a poster session, with about 60 presentations, highlighted the main research activities presently being developed by the network members at the different sites which constitute the NanoSemiMat network. The presentations reflected theoretical and experimental research lines which lead to the development of basic and applied research in nanostructured semiconductor materials such as III,V and II,VI, Si and SiC based nanodevices, wide gap materials, ceramics, polymers, porous materials, optical and transport properties of low dimensional structures, magnetic nanostructures and structures under the influence of high fields, spintronics and sensor applications. The participants of the workshop came from 20 research institutions within Brazil and from 7 research laboratories and universities in Europe and North America. In total about 120 researchers, members of the network, invited researchers, representatives of supporting and funding agencies in Brazil, undergraduate and graduate students, technical staff and supporting personal as well as researchers from complementary fields were present. The realization of the NanoSemiMat-3 was possible due to the financial support of the Brazilian Ministry of Science and Technology (MCT) and the Brazilian National Research Council (CNPq) and the logistic support of Federal University of Bahia. All activities during the NanoSemiMat-3 were open to the general public with interest in nanoscience and nanotechnology. In this third workshop of the series, we highlight the expansion of its format, with plenary and invited talks, poster sessions, as well as the presence of seven invited speakers from abroad. We expect that the continuation of the NanoSemiMat series will be a forum for discussions of state-of-the-art research developed in Brazil on N&N and the multidisciplinary field of semiconductor nanodevices and nanostructured materials as well as its superposition to other branches of science. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Preface: phys. stat. sol. (c) 1/6PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2004Alexey Kavokin This volume contains some of the papers presented at the Third International Conference on Physics of Light,Matter Coupling in Nanostructures (PLMCN3) which took place in Acireale, Sicily, from 1 to 4 October 2003. This meeting was fourth in the series started by PLMCN (St. Nectaire, 2000) and continued by PLMCN1 (Rome, 2001) and PLMCN2 (Rithymnon, 2002). All four conferences had the same format (about 70 participants), similar subject scope (interface between fundamental physics of light,matter coupling phenomena and applied research on new semiconductor materials and low-dimensional structures), and the proceedings of all of them have been published in physica status solidi. During these four years, a huge progress has been achieved in the understanding of exciton,polariton effects in microcavities. From the discovery of stimulated scattering of polaritons in 1999 to the first experimental reports of polariton Bose condensation and lasing, attention to this rapidly developing research area has been increased drastically. It is clear now that realization of a new generation of opto-electronic devices, referred to as polariton devices, is a realistic task for the coming decade. To achieve this target, much work has to be done both in fundamental research on dynamics of exciton,polaritons in microcavities and experimental realization of high-quality microcavities presumably based on wide-band gap semiconductors like GaN, ZnO, ZnSe, suitable for the observation of strong exciton,light coupling at room temperature. Forty nine research teams from twelve European countries have created a Polariton Consortium aimed at integration of the European research effort towards fabrication of polariton devices. PLMCN3 was not only an international conference devoted, in particular, to the research on polariton devices, but also the first scientific meeting of this community. The PLMCN meetings since the very first one have been sponsored by the US Army European Research Office (ERO). This time, with the initiative of Jim Harvey from ERO, a special session has been organized on the devices of 21st century, where a number of intriguing ideas have been proposed on new light sources, polariton lasers, and quantum memory elements based on microcavities. A special prize for the most crazy but realizable idea has been won by Misha Portnoi (Exeter) for the concept of a white diode based on a microcavity. Each PLMCN meeting brings participants from new countries. This time, the traditionally strong participation from Japan, Russia, the European Union and the USA has been enforced by a representative delegation from Israel and two speakers from Mexico. We are looking forward for new-comers from other countries not yet involved in the PLMCN community, to join us for the next meeting to be held in St. Petersburg on 29 June,3 July 2004. Sergey Ivanov from the A. F. Ioffe Institute chairs the local Organizing Committee of this future conference. We are going to keep a unique informal and creative atmosphere being characteristic of the PLMCN meetings. We invite all those who wish to know more about light,matter coupling in solids or to present any new interesting results in this area and at the same time to enjoy the beautiful city of St. Petersburg, to contact Sergey Ivanov (ivan@beam.ioffe.rssi.ru) or myself (kavokin@lasmea.univ-bpclermont.fr). We are looking forward to welcoming you in St. Petersburg! [source] Molecular depth profiling of multilayer structures of organic semiconductor materials by secondary ion mass spectrometry with large argon cluster ion beamsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2009Satoshi Ninomiya In this study, we present molecular depth profiling of multilayer structures composed of organic semiconductor materials such as tris(8-hydroxyquinoline)aluminum (Alq3) and 4,4,-bis[N -(1-naphthyl)- N -phenylamino]biphenyl (NPD). Molecular ions produced from Alq3 and NPD were measured by linear-type time-of-flight (TOF) mass spectrometry under 5.5,keV Ar700 ion bombardment. The organic multilayer films were analyzed and etched with large Ar cluster ion beams, and the interfaces between the organic layers were clearly distinguished. The effect of temperature on the diffusion of these materials was also investigated by the depth profiling analysis with Ar cluster ion beams. The thermal diffusion behavior was found to depend on the specific materials, and the diffusion of Alq3 molecules was observed to start at a lower temperature than that of NPD molecules. These results prove the great potential of large gas cluster ion beams for molecular depth profiling of organic multilayer samples. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||