bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsed-Laser Annealing of Silicon Films
Authors: Sameshima T. 
Published: March 2011

ABSTRACTPhase transition between crystalline and amorphous states was studied through 30ns-pulsed XeCl laser induced melting of silicon films. Crystallization occurs through interface controlled growth for laser energy above surface melting threshold. Grain size is smaller than lOOnm because of short melt duration (<80ns). Amorphization is observed in silicon films thinner than 40nm when the silicon films are completely melted then solidified homogeneously. The amorphized films have a large defect density (∼1020cm-3eV-1), which is remarkably reduced by hydrogen plasma treatment for 1 minute. This paper also discusses the application to fabrication of thin film transistors with a high carrier mobility (>100cm2/Vs) at a low temperature of 250°C.
High-Quality Polycrystalline Silicon thin Films Prepared by Solid Phase Crystallization (Spc) Method
Authors: Matsuyama T. , Baba T. , Tanaka M. , Tsuda S. , Nishiwaki H. , Nakano S. , Hanafusa H. , Kuwano Y. 
Published: March 2011

ABSTRACTThe relationship between the grain size of poly-Si after SPC and the structure of a-Si before SPC was studied. The structure of a-Si was characterized by TA/TO: the Raman intensity ratio of the Transverse Acoustic (TA) like band and the Transverse Optical (TO) like band. A good positive correlation between the grain size and TS/TO was revealed for the first time. The nucleation and growth kinetics were speculated by using a thermodynamic model. The grain size could be enlarged up to 6 μ m by applying textured substrates to a-Si with a large structural disorder. This film was applied to the active layer of solar cells, and a collection efficiency of 51% at 900 nm was obtained.
Origin of Blue Shifts in Quantum-Well Wires Unrelated to Lateral Confinement
Authors: Gustafsson Anders , Liu X. , Maximov I. , Samuelson L. , Seifert W. 
Published: March 2011

ABSTRACTExperimentally observed blue shifts of the peak position of the luminescence from quantum-well-wire and -dot structures are often significantly larger than the calculated shifts induced by lateral confinement in the structures. In this work we have used high-quality InGaAsAnP multi-quantum-wells for the fabrication of wires. The quantum wells are in the range 3 to 17 monolayers (ML) nominally. The thinnest well, 3 ML, shows a clearly resolved split into two luminescence peaks from areas with a thickness difference of 1 ML. In the case of the wires, the luminescence from the thicker wells show a blue shift, as well a significant broadening. However, the thinnest well shows no blue shift, but a different ratio of the two peaks, with the high energy peak favoured in the wire case. We interpret these effects in terms of a reduced transfer of excitons from thinner to thicker areas of the well in the wire as compared to the unpattemed areas. This due to a reduction of the transfer from 2 dimensional to 1 dimensional in the wires. The peaks originating in areas of different ML thicknesses are not spectrally resolved in the thicker wells and the reduced transfer therefore results in a blue shift as well as a broadening of the luminescence peak.
Electron Relaxation in Multisubband GaAs Quantum Wire
Authors: Leão Salviano A. , HipóLito Oscar , Peeters François M. 
Published: March 2011

ABSTRACTThe intra-and intersubband scattering rates for emission and absorption of longitudinal optical (LO) phonons by electrons confined in a cylindrical GaAs-GaAlAs quantum wire are calculated. Multiple peaks due to intersubband transitions appeared on the total scattering rate as a function of the electron energy.
Third-Order Optical Nonlinearities of Quantized CdS and Metal Ultrafine Particles Co-Dispersed in Polymer Matrices – Surface Modification Effect
Authors: Yao Hiroshi , Hayashi Toyoharu 
Published: March 2011

ABSTRACTQuantized CdS particles of about 60 A in diameter were prepared by an organo-sol method in the presence of PVP (poly(N-vinyl-2-pyrrolidone)), and this new method could make the CdS ultrafine particles densely dispersed in PHEMA (poly(2-hydroxyethyl methacrylate)) host films. The values of | x(3) |/α (third-order optical nonlinear susceptibility per unit absorption coefficient) were obtained (2.0 × 10-10 esu· cm at 460 nm and 2.7 × 10-10esu · cm at 470 nm) using a nanosecond DFWM technique. An enhancement of non-linearity was observed for the first time when Ag particles or Ag+ ion were co-dispersed with the CdS particles in small amounts. The addition of 8.57 wt% Ag particles, or 4.28 wt% Ag+ ion in the ratio to CdS made | x(3) |/α enhanced to be 3.9 × 10-10 esu· cm, or 4.1 × 10-10 esu· cm, respectively. The surface modification by the formation of Ag2S on the surface of CdS colloids is believed to be responsible for this enhancement.
Blue Light Emission from Porous Silicon
Authors: Hou X. Y. , Shi G. , Wang W. , Zhang F. L. , Hao P. H. , Huang D. M. , Jin X. F. , Wang Xun 
Published: March 2011

ABSTRACTThrough a post treatment of light emitting porous silicon in boilingwater, a large blue shift of its photoluminescence (PL) spectrum hasbeen observed and a stable blue-green light emission at the peak wavelength down to 500 nm is achieved. The effect of boiling water treatment is suggested to be a kind of oxidation, which could reduce thesize of the Si column, fill up some micropores and strengthen the Siskeleton. The photoluminescence microscopic observation shows that the surface of blue light emitting porous silicon is composed of manysmall uniformly light-emitting domains at the size of several tens of μm. Fourier transform infrared reflection (FTIR) measurements show that the formation of Si-H bonds is not responsible for the visible luminescence in the very thin Si wires.
Optical Properties of Colloidal MoS2
Authors: Wagoner G. A. , Persans P. D. , Ruppert A. F. 
Published: March 2011

ABSTRACTWe report measurements and analysis of the optical transmission spectra of colloidal 2H-M0S2. prepared by ultrasonic shattering of synthetic crystals in N-Methyl Formamide. We used a combination of TEM, X-ray diffraction and dynamic light scattering to characterize particle shape and size. For a typical sample, the particles are platelets which have an average thickness of 50 Å and a diameter of 500 Å. Particle dielectric functions, deduced from both dilute colloids and thin films prepared by flocculaUon, differ significantly from bulk values. Calculations show that the average extinction coefficient is affected by particle aspect ratio, but this can not explain all the features of the data. Specifically, we observe a suppression of the absorbance peaks in the band edge exciton region between 1.7 and 2.1 eV, and increased absorbance below 1.7 eV. We suggest that the particles do not possess bulk-like dielectric properties and that tins is due to defects.
Microcharacterization of CuInSe2 Grown by Coevaporation and Selenization
Authors: Bode M. H. , Al-Jassim M. M. , Tuttle J. , Albin D. 
Published: March 2011

ABSTRACTThin films of CuInSe2, grown by coevaporation or by selenization of a Cu-In precursor, were analyzed in a scanning transmission electron microscope. While the coevaporated film shows clear evidence of second phases (Cu2Se) around the individual grains, no second phases could be found in the selenized material. Structural characterization also showed the presence of two ordered phases in the coevaporated films, the ordered-vacancy compound CuIn2Se3.5, and a CuPt-ordered phase of CuInSe2.
Rapid Thermal Annealing of Spin-On Glass Films
Authors: Ventura Laurent , Hartiti Bouchaíb , Slaoui Abdelilah , Muller Jean-Claude , Siffert Paul 
Published: March 2011

ABSTRACTRapid thermal annealing is investigated for curing spin-on glass insulating films. The annealed SOG films were mainly evaluated using infrared absorption spectroscopy and by electrical measurement of the defects present at the Si/Sio2 interface. We found in particular after rapid thermal annealing an important densification of the layers as a function of temperature and a reduction of the interfacial state densities which are comparable to classical thermal oxides.
Voltage, Fluence, and Polarity Dependence of Trap Generation Inside of Thin Silicon Oxide Films
Authors: Scott Ronald S. , Dumin David J. 
Published: March 2011

ABSTRACTThe tunnelling front model has been used to obtain the spatial distribution of high-voltage, stress generated traps inside of MOS capacitors. It was found that the number of traps created by high voltage stress was proportional to the cube root of the fluence through the oxide during the stress. Measurement of the trap generation rate indicated that fewer traps were being created as higher amounts of charge were passed through the oxide. Further tests indicated that there was a voltage dependence to the trap generation which was independent of stress polarity.
Stress Induced Increased Low Level Leakage in Thin Oxides
Authors: Dumin D. J. , Maddux J. R. , Wong D.-P. 
Published: March 2011

ABSTRACTIt has been observed that the low-level, pre-tunneling currents through thin gate oxides increased after the oxides had been stressed at high voltages. The number of traps inside of the oxide generated by the stress has been shown to increase as the 1/3 power of the fluence that had passed through the oxide during the stress. The increases in the low-level, pre-tunneling currents have been shown to be proportional to the number of stress generated traps in the oxide and not to the fluence during the stress. The voltage dependences of the excess low-level leakage currents were stress and measurement polarity dependent. Attempts have been made to fit the voltage dependences of the excess low-level currents to Fowler-Nordheim tunneling, Frenkel-Poole conduction or Schottky barrier lowering. The increase in the portion of the low-level, pre-tunneling current that was not dependent on stress/measurement polarity sequence was best fit using Schottky emission currents. The model that has been developed to describe the increases in the low-level currents has centered on trap-assisted currents through the oxides.
Development of Aluminum Gate Thin-Film Transistors Based on Aluminum Oxide Insulators
Authors: Tsukada Toshjhisa 
Published: March 2011

ABSTRACTDevelopment of aluminum gate thin-film transistors (TFT) is described. This TFT is fabricated based on an aluminum oxide insulator technology, in which aluminum is anodically oxidized to form Al2O3. The use of aluminum is effective in reducing the delay of the gate busline of the display panels due to its low resistivity. The Al2O3 films formed by an anodic oxidation, block the growth of hillocks during TFT fabrication which is one of the biggest issues of aluminum metallization. With this technology it is possible to design and fabricate TFT/LCD panels larger than 30 inches and with more than 1000 scan lines.
High Channel Mobility a-Si:H Thin Film Transistors with Oxide/Nitride Dielectrics
Authors: He S. S. , Stephens D. J. , Lucovsky G. , Hamaker R. W. 
Published: March 2011

ABSTRACTWe describe: i) nitride-layer optimization; ii) device fabrication: and iii) electrical properties of a-Si:H thin film transistors, TFTs, that integrate oxide/nitride dielectrics into an inverted, staggered gate structure. We have systematically changed the concentrations of Si-Si, Si-H and Si-NH bonding groups within the deposited nitride layers by varying the source gas flow ratio, R = NH3/SiH4 from 2.5 to 12.5. The electrical characteristics of the TFTs improve significantly as the gas phase ratio R is increased from 2.5 to approximately 10, and then decrease as R is further increased. The performance of the TFTs peaks for a source gas ratio of -10, where the channel mobility is ∼1.4 cm2/V-s, the threshold voltage is 2.3 V; and the Ion to Ioff current ratio is > 105.These increases in performance can only realized in devices in which the back of the Si channel region is passivated with an oxy-nitride interfacial region.
Electrical Properties of Tantalum Based Composite Oxide Films
Authors: Kattelus Hannu , Ylilammi Markku , Salmi Jorma , Ranta-Aho Timo , Kanen Erjany , Suni Andilkka 
Published: March 2011

ABSTRACTTantalum oxide is a widely used insulator in electronic applications requiring high permittivity. When deposited at low temperature, tantalum oxide films, however, often exhibit large leakage current. A common way to reduce leakage is to anneal the films in an ambient containing extremely reactive oxygen species, or at high temperature in dry oxygen. A different approach is to use composite oxide materials. We have studied layered tantalum based oxide films deposited by Atomic Layer Epitaxy, and observed that the leakage current is decreased by several orders of magnitude when a fraction of tantalum oxide is replaced by another oxide, such as aluminum or hafnium oxide. Leakage current density of 40 nA/cm2 in the electric field of 1 MV/cm is attained for unannealed Ta-Hf-O film deposited at 300°C. Layered composite insulators are an interesting new class of materials, and ALE proves to be a useful method for depositing them.
Electrical Properties of Ferroelectric Thin Film Capacitors with Different Structures
Authors: Jia Q. X. , Yi J. , Shi Z. Q. , Ho K. K. , Chang L. H. , Anderson W. A. 
Published: March 2011

ABSTRACTFerroelectric BaTiO3 thin film capacitors were fabricated using different designs. Silicon wafers with an oxide layer were used as the substrates. Conductive metallic oxide of RuO2 was reactively sputtered on SiO2/Si as a bottom electrode. The BaTiO3 thin films with a thickness in the range of 150–300nm were deposited by RF magnetron sputtering. Different capacitor structures, including single layer amorphous, single layer polycrys-talline, and bi-layer amorphous on polycrystalline, were investigated in this study. The clear interface between BaTiO3 and RuO2 as demonstrated by cross-sectional scanning electron microscopy implies little interdiffusion. The DC conducticity of a film with a thickness of around 200nm was as low as 1×10−13OHgr-cm at 4V. The dielectric constant of the composite structure was controlled in a range from 30 to 130. Breakdown voltage varied from 5×105V/cm to 1×106V/cm.
Non-Contact Real-Time Evaluation of Polyimide Thin Film Thermoelastic Properties Through Impulsive Stimulated Thermal Scattering
Authors: Rogers J. A. , Duggal A. R. , Nelson K. A. 
Published: March 2011

ABSTRACTWe demonstrate a new purely optical based method for the excitation and detection of acoustic and thermal disturbances in thin films. This technique is applied to the determination of the viscoelastic properties of unsupported and silicon supported polyimide thin (∼1 micron) films. We show how this technique can be used to detect film delaminations and suggest how it may be used to probe film-substrate adhesion quality.
Polysilicon and Simox Characterization Using Spectroscopic Ellipsometry
Authors: Asinovsky L. M. 
Published: March 2011

ABSTRACTSpectroscopic ellipsometry has been used to characterize Poly-Si, prepared with the bulk LPCVD technology and SIMOX samples. SIMOX samples were prepared by implantation of the oxygen ion (≈ 1.8×1018ions/cm2 at 200keV) of the c-Si substrate and annealing at 1300°C for 5 h. The measurements were taken at angles of incidence of 65 and 70 degrees in the wavelength range from 260 to 860 nm. The analysis of the data identified the presence of the inhomogeneity in the poly-Si layer and slight deviation of the Si layer optical constants spectra from that of the c-Si in the SIMOX sample. A method is presented that provides a step by step procedure for interpretation of the spectroscopic ellipsometry measurements.
Room Temperature Photoluminescence Spectra of Annealed PECVD Silicon Nitride Thin Films
Authors: Savall C. , Bustarret E. , Stoquert J. P. , Bruyére J. C. 
Published: March 2011

ABSTRACTWe present the changes upon isochronous annealing in the room temperature photoluminescence (PL) spectra of nearly stoichiometric silicon nitride. Samples are prepared by the 50kHz PECVD of a N2/SiH4/Helium gas mixture at 350°C. In the as-deposited films the hydrogen content was around 11% for a refractive index of 1.98. For a photoexcitation at 351 nm, the polarized PL spectrum of the as-deposited film is characterized by a main broad emission band in the visible region with a maximum at 2.55eV. A second narrow peak (FWHM = 55meV), at 3.02eV is observed. We study the evolution of the PL spectra with different isochronous anneals from 350°C to 1000°C. Even though the general shape of the PL spectra does not change, we observe an increase of quantum efficiency with maximum value upon 750°C annealing. Beyond this temperature the low energy part of the PL spectrum shows a slight increase. These variations are compared to those of the infrared absorption peaks measured on the same samples. Both the temperature dependence of the intensity of a well defined absorption peak in the Si-H stretching mode region and that of the PL features can be explained assuming that solid state chemical reactions involving hydrogen and Si-Si bonds occur in the bulk of the alloy.
Electrical Properties of Silicon Nitride Thin Films Fabricated by ECR PECVD at Room Temperature
Authors: Jeon Yoo-Chan , Lee Hoyoung , Joo Seung-Ki 
Published: March 2011

ABSTRACTSilicon nitride thin films were deposited on single crystalline silicon substrates at room temperature by ECR PECVD with SiH4 and N2 as source gases and the electrical properties were analyzed. The dominant conduction mechanism in a high field was Poole-Frenkel emission. A ledge in I-V curve was observed in the first voltage ramp and it was found to originate from the field reduction at the injecting electrode due to the charge trapped in deep traps in the film. It also turned out that the ledge is a characteristic of monopolar conduction. A new interpretation of the current at low field — tunneling into trap states — was proposed and the current variations according to the field and temperature could be well explained.
Excimer Laser Interaction with Metals
Authors: Duley W.W. , Kinsman G. 
Published: March 2011

ABSTRACTExcimer laser radiation may be used to process metal surfaces in a variety of novel ways. The simplest of these involves the use of UV laser pulses for ablation. Ablation occurs as the result of both vaporization and hydrodynamical effects. Experimental data related to these processes will be discussed. In addition, it will be shown how specific irradiation regimes can yield metal surfaces with unique radiative properties.
A Comparative Study of the Photoablation of Polyimide-Doped Poly(Tetrafluoroethylene) at 308 NM and 248 NM
Authors: D'couto G. C. , Babu S. V. , Egitto F. D. , Davis C. R. 
Published: March 2011

ABSTRACTExperimental data on the 248 nm and 308 nm wavelength excimer laser ablation of poly(tetrafluoroethylene) (PTFE) doped with polyimide (PI) are reported for a range of fluences and dopant concentrations. Threshold fluences were determined and correlated with the dopant concentrations. The threshold fluences and the limiting etch rates measured at high fluences decreased with increasing dopant concentration and there is a minimum absorption coefficient below which there is no ablation at both the wavelengths. The etch rates have been modeled using a two parameter Arrhenius thermal model to describe the etching process.
Development of a Simple and Highly Sensitive Microbalance for Measurements of Total Particle Yields in Matrix Assisted Laser Desorption
Authors: Huth-fehre T. , Quist A.P. , Linder S-O. , Sundqvist B.U.R. 
Published: March 2011

ABSTRACTIn order to open a new window for getting insight into the process of matrix assisted laser desorption ionization (MALDI) of biopolymers, a highly sensitive quartz crystal microbalance (QCM) was developed to measure desorption yields of neutral particles. For the matrix substances commonly used the mass resolution of 0.95 ng obtained with the balance corresponds to a detection limit of ∼1012 particles.
Tunable Laser Desorption from Diamond Films and Pyrolytic Graphite
Authors: Ueda A. , Mckinley J. T. , Albridge R. G. , Barnes A. V. , Tolk N. H. , Davidson J. L. , Languell M. L. 
Published: March 2011

ABSTRACTWe report the observation of wavelength-dependence in the early phases of the laser ablation of chemical vapor deposited (CVD) diamond films. The measurements were made with 3–4 μm infrared radiation from the Vanderbilt Free-Electron Laser (FEL), the brightest tunable mid-infrared FEL in the world. Though we do not propose any specific mechanism for the ablation, the C-H bond-stretching mode at 3.47 μm is clearly important in the early stagesof the damage process, as evidenced by a sharp drop in the ablation threshold near 3.47 μm.The ablation damage threshold was determined by directing a single FEL pulse at the sampleand measuring the diameter of the resulting hole using a scanning electron microscope (SEM).This measurement was repeated for several pulse intensities. The damage threshold was defined as the extrapolation to zero hole diameter. We also looked at the desorption productsusing a time-of-flight spectrometer and a quadrupole mass analyzer. C2 is the dominant desorbed species. Visible light emission was monitored with a monochromator and photodetector.
Atomic Layer Growth of High Tc (Ca,Sr)CuO2 Thin Films by Laser Mbe
Authors: Kana M. , Kawai T. , Kawai S. 
Published: March 2011

ABSTRACTResistive and magnetic anomalies were observed at 150-170K in Ca0.3Sr0.7CuO2 thin films prepared by atomic-layer stacking using laser molecular beam epitaxy. Systematic current density dependence of the resistivity was observed below these temperatures with clear resistivity drops. At the same temperature range, the films showed diamagnetic response and hysteresis of magnetization between zero-field cooling and field cooling process. These behaviors suggest that the anomalies are due to high temperature superconductivity around 150-170K in the Ca0.3Sr0.7CuO2 thin films.
Rheed-Oscillations During Pulsed Laser Deposition of YBCO
Authors: Karl H. , Stritzker B. 
Published: March 2011

ABSTRACTReflection high-energy electron diffraction (RHEED) oscillations during pulsed laser ablation of YBCO on SrTiO3(100) substrates were measured. We found that the oscillations are modulated by the laser-pulse repetition frequency, due to diffuse scattering by the initially disordered YBCO material. Since the disordered YBCO crystallizes the specular intensity recovers exponentially with time. An estimate of the diffusion length was obtained by measuring RHEED oscillations during deposition on slightly misoriented SrTiO3(100). From the rise time of the RHEED signal and the mean diffusion length a diffusion constant of 1.4*10−2cm2/sec was determined [1].