bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrafast Carrier Dynamics and Recombination in Green Emitting InGaN MQW LED
Authors: Cartwright Alexander N. , Cheung M. C-K. , Shahedipour-Sandvik F. , Grandusky J. R. , Jamil M. , Jindal V. , Schujman S. B. , Schowalter L. J. , Wetzel C. , Li P. , Detchprohm T. , Nelson J. S. 
Published: April 2011

AbstractTime-resolved photoluminescence studies can provide useful information for the development of InGaN/GaN heterostructures for long wavelength visible emitters. In this paper, we present results of time-resolved photoluminescence from samples grown using two different approaches to achieve green emission from InGaN/GaN MQWs. In one approach, samples, with high indium incorporation, were grown on a high quality AlN substrate to achieve green emission. The resulting photoluminescence decay of the green luminescence is long-lived and non-exponential. Quantitative analysis showed that the decay has a stretched-exponential characteristic, typical of InGaN/GaN MQW with potential fluctuation along the growth plane. This carrier localization, in a structure with low defect density, proves to be an effective means to achieve green emission. In another approach, a piezoelectric Stark-like ladder effect is used. In this case, a methodical layer-by-layer growth homogeneity optimization process was adopted to achieve an optical transition below the electron to heavy-hole (e1hh1) transition when the quantum well is subjected to the strong piezoelectric polarization dipole. This approach has proven to be successful in achieving green luminescence on conventional sapphire substrates. The resulting photoluminescence decay at 14 K, of a sample grown by this approach, is single exponential and shorter in duration than the decay observed in the first approach. This exponential decay is consistent with previous AFM studies that revealed a homogeneous active region.
Effects of Nitrogen Reactive Species on Germanium Plasma Nitridation Processes
Authors: Sugawara Takuya , Sreenivasan Raghavasimhan , McIntyre Paul C. 
Published: April 2011

AbstractRoles of reactive species of germanium and silicon plasma nitridation were investigated by comparing nitrogen plasma chemistry and oxynitride layer physical properties. In high pressure remote plasma nitridation process, hydrogen containing neutral radicals (NH* and H*) were important to nitride germanium and silicon substrates. This process required high substrate temperature to nitride germanium substrate, whereas silicon substrates could be nitrided at low substrate temperature. In low pressure RLSA plasma nitridation process, N2+ ion species acted as dominant reactive species. Using this process, germanium could be nitrided at low substrate temperature without hydrogen and high nitrogen concentration (~22at.%) GeON was obtained.
Wet Chemical Cleaning of Germanium Surfaces for Growth of High-k Dielectrics
Authors: Amy Sandrine Rivillon , Chabal Yves J , Amy Fabrice , Kahn Antoine , Krugg Cristiano , Kirsch Paul 
Published: April 2011

AbstractOne of the major difficulties preventing the wide use of germanium (epi or bulk) as a gate material is the poor stability of its oxide, leading to reproducibility and reliability issues. In contrast to silicon, the nature and thickness of Ge “native” oxides are history dependent, and most phases of germanium oxide are water-soluble. As a result, the procedures for passivating Ge surfaces with hydrogen (HF last) are more complex and less forgiving.We have used infrared absorption spectroscopy and x-ray photoelectron spectroscopy to investigate the nature of oxidized and H-terminated Ge surfaces. The GeO2, GeO and GeC phases have been identified and quantified as a function of processing conditions. The stability of the H-terminated surfaces has been examined in air and in controlled environments. The H-passivated Ge surfaces are found to be much less stable in air than H-terminated Si surfaces.
Impact of TiN/HfO2 Integration on Carrier Mobility
Authors: Casse Mikael , Thevenod Laurent , Guillaumot Bernard , Tosti Lucie , Cosnier Vincent , Mitard Jerome , Reimbold Gilles , Billon Thierry , Mouis Mireille , Boulanger Fabien 
Published: April 2011

AbstractWe have investigated the impact of a metal gate (TiN) and high-k dielectric (HfO2) on the carrier mobility. We have shown that strong remote Coulomb scattering (RCS) due to charges in the HfO2 layer (either grown by ALD or MOCVD) mostly degrades the mobility at low/medium field. High amount of charges (>1013cm-2) is needed to explain the 30% degradation observed in devices with a thin interface layer. These additional coulombic interactions are effective for bottom oxide up to 2nm. We have developed a RCS model to fully explain the experimental data. The influence of the metal gate is also evidenced. The latter has a significative impact on the Si/SiO2 interface roughness, and may induce some additional coulombic interactions.
Ru/Ta Alloying Behavior and its Implications for Laminate Based CMOS Integration
Authors: Lisoni Judit G. , Schram Tom , Witters Thomas , Van Hoornick Nausikaa , Yamada Naoki , De Gendt Stefan 
Published: April 2011

AbstractThe microstructural and electrical characterizations of RuxTa1-x alloys obtained from Ru-Ta laminates are presented. The films were deposited on SiO2 and HfO2 and capped with TiN to avoid oxidation of the top surface. The alloys were attained by post-anneal thermal treatments in the range of 500-1000 °C in Ar atmosphere. Co-sputtered RuxTa1-x alloys were used as references. In particular, Ru0.4Ta0.6 phase could be obtained when the Ru-Ta laminate was annealed at 1000 °C. The alloying reaction is limited either by the tantalum nitride or oxide formation being the source for Nitrogen the TiN capping used on top of the stack and the Oxygen either the dielectric films or the one stuffing the films after exposure to the atmosphere.Independent of the Ta content a mid gap work function was obtained. Measured WF's in laminate-obtained alloys and alloys themselves differ from other literature data, where a more n-type like WF are measured, and indicating process dependence. In the present study mid-gap or rather p-type work functions were found, 4.5 eV < WF < 4.9 eV.
Non-contact Corona-Kelvin based Metrology for High-k Dielectric Characterization with an Extension to Micro-Scale Measurement
Authors: Wilson Marshall , Marinskiy Dmitriy , Almeida Carlos , Kochey Joseph N. , Byelyayev Anton , Savtchouk Alexandre , D'Amico John , Findlay Andrew , Jastrzebski Lubek , Lagowski Jacek 
Published: April 2011

AbstractIn-line monitoring of the electrical properties of high-k dielectrics in logic or memory fab-lines has become increasingly important in the semiconductor industry. Non-contact corona-Kelvin based metrology can be used to affectively monitor in-line key dielectric properties. Furthermore, we present an important extension of this metrology to the micro-scale that allows measurement of dielectric properties on test sites as small as 40μm × 70μm. This is achieved through miniaturization of the corona charging apparatus and of the Kelvin probe without a sacrifice in precision or repeatability. Corona-Kelvin micro-metrology allows for the monitoring of the critical dielectric properties directly on product wafers that can then be returned to the fab-line for continued processing. Application examples are given for dielectric capacitance of advanced dielectrics and for the properties of an oxide-nitride-oxide (ONO) memory structure. In the latter case we demonstrate programming and erasing of the ONO structure realized by corona charging. We also use the measured flatband voltage and total charge to identify the location of the programmed charge at the first SiO2/Si3N4 interface in the ONO structure.
Highly Scalable ALD-deposited Hafnium Silicate Gate Stacks for Low Standby Power Applications
Authors: Swerts Johan , Deweerd Wim , Wang Chang-gong , Fedorenko Yanina , Delabie Annelies , Shero Eric , Zhao Chao , Maes Jan Willem , De Gendt Stefan , Wilk Glen 
Published: April 2011

AbstractThe electrical performance of hafnium silicate (HfSiOx) gate stacks grown by atomic layer deposition (ALD) has been evaluated in capacitors and transistors. First, scaling potential of HfSiOx layers was studied as function of composition and thickness. It is shown that the equivalent oxide thickness scales down with decreasing layer thickness and increasing Hf-content. The gate leakage (at Vfb-1V), however, is mainly determined by the physical layer thickness. For the same equivalent oxide thickness (EOT) target, the lowest leakage is observed for the layers with the highest Hf-content. Leakage values as low as 1x10-3 A/cm2 for an equivalent oxide thickness of 1.3 nm have been obtained. Second, the thermal stability against crystallization of the ALD HfSiOx has been studied and related to their electrical properties. The thermal stability of HfSiOx decreases with increasing Hf-content that necessitates the use of nitridation. The influence of various annealing conditions on the nitrogen incorporation is also studied. Finally, the effect of HfSiOx composition and postdeposition nitridation is discussed on transistor level. TaN metal gate transistor data indicate that nitridation reduces the gate leakage and that Hf-rich HfSiOx layers show the best scaling potential, i.e., highest performance for the lowest gate leakage.
Study of Magnetron Sputter Deposition of Metal Gate Electrodes
Authors: Ye Mengqi , Liu Dave , Ding Peijun , Hung Steven , Ahmed Khaled 
Published: April 2011

AbstractA systematic study of magnetron sputter deposition of metal gate is presented. On-wafer probes were used to measure ion current and floating voltage. Charge monitoring wafers was used to evaluate charging damage. C-V measurements showed that the interface trap density of metal gated MOS capacitors was reduced with thicker dielectric layer thickness and with the insertion of ALD deposited buffer layer. Lower pressure, higher sputtering power, and pulsed DC sputtering were found to cause larger plasma damage to the ultra-thin dielectric layer, most likely due to increased energetic particle bombardment as a result of higher plasma density and higher ion and neutral energies.
Structural and Optical Properties of Amorphous Ge2Sb2Te5
Authors: Li Heng , Ju T. , Herring T. , Taylor P. C. , Williamson D. L. , Nelson M. J. , Inglefield C. E. 
Published: April 2011

AbstractThe optical and structural properties of amorphous sputtered films of Ge2Sb2Te5 depend strongly on the preparation conditions. Films grown at higher growth rates exhibit greater local strains as indicated by the slope of the optical absorption in the exponential “band-tail” region, but these films also incorporate smaller densities of oxygen impurities. At slower growth rates the band-tail slopes are sharper (smaller local strains) but there is greater oxygen incorporation. We will discuss several experiments that suggest that the local strain relief in the films grown at slower growth rates is due to a greater ability of the atoms to rearrange on the growing surface and not to increased oxygen incorporation. Small angle x-ray scattering experiments show that the films exhibit small elliptical “voids” with long axes perpendicular to the growing surface. The approximate dimensions of these voids are 3 × 20 nm. These films can be switched optically with little change in surface topography as measured by atomic force microscopy. Electron spin resonance measurements indicate that paramagnetic defects exist in some films but are either absent or below the detection limit (~ 1018 cm-3) in most films. The implications of these results for the switching mechanisms will be discussed.
Fast Photodarkening in Amorphous and Liquid Chalcogenide
Authors: Sakaguchi Yoshifumi , Tamura Kozaburo 
Published: April 2011

AbstractTransient photo-induced optical absorption in amorphous and liquid As2Se3 was investigated using a nanosecond pulsed laser and a specially designed optical cell. The measurements have been performed in the second and minute domain and the nanosecond and microsecond domain. From the measurements in the second and minute domain using repeated illumination, we observed the accumulation of photo-induced absorption and the decay after stopping the illumination. The durable photodarkening was also observed after the decay. The accumulated photoinduced change becomes smaller with increasing temperature and approaches to be zero around the glass transition temperature. From the measurements in the nanosecond and microsecond domain, the transient photodarkening in the time domain responded for each pulsed laser was observed. This fast photodarkening was observed even in the liquid state. This is contrast to the cases of the durable photodarkening and the transient photodarkening in the second and minute domain. The origin of the observed photoinduced changes is discussed.
Phase Transformations in Bulk (Ge2Se7)88Bi5Sb7
Authors: Adriaenssens Guy J. 
Published: April 2011

AbstractAnnealing at 150 °C induces phase separation in amorphous (Ge2Se7)88Bi5Sb7 bulk samples. Spectrally resolved steady-state photoconductivity measurements indicate the presence of crystalline Bi2Se3 clusters in the annealed material, but also the subsequent gradual disappearance of this microstructure at room temperature. Similar annealing-induced metastable changes are observed in other elements of a (Ge2Se7)88BixSb12-x sample series.
Chemical Route Fabricated Magnetic Structure Exhibiting a Negative Permeability at Infrared Frequencies
Authors: Liu Hui , Zhao Xiaopeng 
Published: April 2011

AbstractWe propose a quasi-periodic dendritic resonant magnetic model that can be used for the realization of the negative permeability at infrared frequencies. The numerical simulation exhibits a magnetic response when the incident light is perpendicular to the plane of the model. The copper dendritic structures are prepared by the electro-deposition method. And the transmission spectrum of this dendritic structure shows a magnetic response at infrared frequencies with a maximum transmission ¨C7.95dB. Further studies demonstrate that the magnetic response relate to the fractal dimension of the dendritic structure to a certain extent.
Negative Permeability of Single-ring Split Ring Resonator in the Visible Light Frequency Region
Authors: Tanaka Takuo , Ishikawa Atsushi , Kawata Satoshi 
Published: April 2011

AbstractNegative permeability of single-ring split ring resonator (s-SRR) is theoretically investigated in the visible light frequency region [1, 2]. To estimate magnetic responses of conductive elements precisely, we determined internal impedance by considering the delay of the current inside the metal structure. The increase of the surface resistivity, which is the real part of the internal impedance, results in the decrease of the resonator's Q-value. This means the degradation of the tunable range of the permeability. The increase of the internal reactance results in the reduction of the resonant frequency. In our calculation, the surface resistivity saturates at the inherent frequency of each metal as the frequency increases. On the silver case, the saturation value is 0.4 Ω and this value is remarkably smaller than that of gold and copper. On the other hand, the internal reactance is increasing as the frequency increases independently of metal. We concluded that the internal reactance is dominant factor to realize the negative magnetic permeability in the optical frequency region. We also show the frequency dependence of the magnetic permeability of s-SRRs. In the case of s-SRRs made of copper, the minimum value of the magnetic permeability becomes positive value at 550 THz even in the high filling factor condition (11%). In the case of s-SRRs made of gold, only on the filling factor was 11%, the minimum value of the magnetic permeability takes negative value in the entire visible range. On the other hand, the silver SRR exhibits negative magnetic permeability in the visible range even under the low filling factor condition of 3%. Moreover, we concluded that reducing the geometrical capacitance and using silver for SRR are necessary to realize the negative magnetic permeability in the visible light range.
Functionalisation of Textiles with Nanotechnology
Authors: Textor Torsten , Schröter Frank , Schollmeyer Eckhard 
Published: April 2011

AbstractThe present development of textile market is connected with an ever increasing demand for new functionalities for highly specific applications. At the same time, the industrial supply has been restricted to only a few types of synthetic fibers. Given that background, surface modification became one of the most important topics to create new textiles. Beside other techniques, the functionalisation of fibers by making use of concepts of the nanotechnology is part of our work for several years. Coatings based on nanosols and inorganic-organic hybrid polymers, derived from sol-gel process, have an immense potential for creative modifications of surface properties and can be applied with a comparatively low technical effort and at moderate temperatures. The coatings often combine properties of organic polymers with those of ceramic materials [1-11]. Therefore those hybrid polymers are of an enormous interest for technical textiles. The basic materials offer the opportunity to produce very hard but flexible coatings, especially by filling or modifying the networks with nano-particles. Approaches to modify these systems by various inorganic or organic substances can lead to a huge number of additional functionalities which are increasingly demanded from the textile industries [12-18]. Coatings of a thickness of less then one micron can act as effective barriers against chemical attacks, super-repellent surfaces can be created, or the wear-resistance of textile materials can be improved. Coatings incorporating nanoparticles as employed in sun creams protect sensitive polymers against decomposition due to ultraviolet radiation. Ballistic body wear based on fabrics protects against gun attacks but generally not against knives. For these products, thin coatings based on inorganic-organic hybrid polymers filled with alumina nanoparticles were found to give good stab-resistance. Further approaches deal e.g. with reversible photochromic coatings – coatings that change its color if irradiated with sun light -, (superpara-)magnetic hybrid polymers or medical systems based on porous sol-gel-coatings with immobilized drugs that are released in contact with skin. This paper will focus on approaches to improve ballistic body wear with respect to stab-resistance, UV-protection and water and oil repellence.
Suspension of Silver Oxide Nanoparticles in Chitosan Solution and its Antibacterial Activity in Cotton Fabrics
Authors: Hu Zhigang , Zhang Jin , Chan Wing Lai , Szeto Yau Shan 
Published: April 2011

AbstractNew stable silver oxide suspension in chitosan solution was prepared from a mixture of silver nitrate and chitosan in dilute acetic acid as precursor, in which the complex interactions between silver ion and chitosan was also investigated through various instrumentation method seriously. The suspension was charactized through laser scan, infrared ray spectroscopy (IR), ultraviolet-visible spectroscopy (UV-vis) and X-ray diffraction (XRD), which indicated that the interactions between silver and chitosan in its precursor were destroyed partially. The measurements of the nanoparticles through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) disclosed the spherical profiles of these silver oxide nanoparticles of 10-20nm in average. Cotton fabrics treated by this emulsion were entitled remarkable antibacterial activity against S aureus and E. coli at pH 5 and 7 with sightless color effect and good washing fastness.
Controlled Conductive Polymer Coating on Wood Microfibers via Layer-by-layer Nanoassembly
Authors: Agarwal Mangilal , McDonald John , Lvov Yuri , Varahramyan Kody 
Published: April 2011

AbstractThis paper reports on layer-by-layer (LbL) self-assembly of poly (3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) conducting polymer on lignocellulose wood microfibers to make conducting paper. Polycation such as poly(allylamine hydrochloride) (PAH) was used with polyanionic PEDOT-PSS to construct the multilayers. The physical characterization of the microfiber was done using roughness step tester (RST) and surface profilometer (TENCOR). Thickness of the coated film was estimated using a quartz crystal micro-balance. Current – Voltage characterization was performed using a Keithley measurement system after each self-assembly of PEDOT-PSS to study the electrical properties of the coated film. It was observed that the conductivity of the microfiber was proportional to the number of polyelectrolyte bilayers deposited. The measured conductivities ranged from (1 to 5) × 10-3 Scm-1 to 1 to 10 Scm-1 for different bilayers of PEDOT-PSS on wood microfibers. It was also observed that the conductivity of the nano-coated fibers is dependent upon the salt concentration used in PAH polycations to from the multilayer. In this work we are developing scale integration from nano, to micro and macro (nanocoating-microfibers-macropaper). The results obtained show great promise for the development of smart paper technology and its contribution to the economic development of the nation.
Modified Cotton Fiber Surface for Apatite Growth and Cell Affinity
Authors: Fei Bin , To Shing Shun Tony , Qi Kaihong , Xin John H. 
Published: April 2011

AbstractIn order to bring widely distributed polysaccharides materials into more medical applications, cotton fiber surfaces were modified into substrates for apatite deposition. Using a solid phase reaction, cotton fibers were conveniently carboxylated in large scale. The carboxylated cotton fibers were coated by apatite in a biomimetic way. Through soaking in a concentrated simulated body fluid (SBF × 5), nano-size apatite particles rapidly and finely grew on the fiber surfaces. The nucleation and growth of apatite was investigated with the aid of scanning electron microscopy (SEM). In comparison to pure cotton, the cotton coated with apatite showed improved cell affinity to osteoblast-like cells.
Polypyrrole-coated Large Deformation Strain Fabric Sensor and its Properties Study
Authors: Cheng Xiaoyin , Tsang H. Y. J. , Li Y. , Leung M. Y. , Tao X. M. , Cheng X. X. , Xue P. , Yuen C. W. M. 
Published: April 2011

AbstractConductive-polymer coated fabrics have been investigated as intelligent materials in the past years. In this paper, a flexible fabric strain sensor coated with polypyrrole is reported, which is featured with high sensitivity, good stability and large deformation. It is fabricated by chemical vapor deposition at low temperature. The effects of temperature, humidity, acid and alkaline medium have been assessed. The conductivity-strain tests reveal the sensor exhibits a high strain sensitivity of ~160 for a deformation as large as 50%, while its good stability is indicated by a small loss of conductivity after the thermal and humidity aging tests, and supported by the slight change in conductivity and sensitivity over a storage of eighteen months. The acid and alkaline solution mainly decreased their initial conductivity but have the slight effect to their sensitivity. The flexible fabric strain sensor is expected to be a promising “soft” smart material in the smart garment, wearable hardware and biomedical applications.