bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advanced Concept of Partitioning for Transmutation Treatment in Improved Geologic Disposal of HLW
Authors: Kitamoto Asashi 
Published: April 2011

ABSTRACTGeologic disposal scenario combined with multiple-recycle P&B/T (partitioning, and burning and/or transmutation) treatment has some potential merits to complete the current geologic disposal scenario, and is discussed herein based on three plus two criteria for partitioning. The important gain of P&B/T treatment is that an unanticipated uncertainty due to geologic behavior for near and far field of repository can be avoided without verification for super-long period. The number reduction of GSC (glass solidified canister, i.e. waste package)is another important gain of P&T treatment to decrease the cost of geologic disposal, because the number reduction of GSC can save the total cost for the current disposal scenario
The Relative Radiation Resistance of Zirconolite, Pyrochlore, and Perovskite to 1.5 MeV Kr+Ions
Authors: Smith Katherine L. , Zaluzec Nestor J. , Lumpkin Gregory R. 
Published: April 2011

ABSTRACTZirconolite (CaZrTi2O7), pyrochlore (vIIIA2VIB2IVx6y) and perovskite (CaTiO3) are candidate phases for the immobilisation of rare earth elements (REEs) and actinides (ACTs) in various high level radioactive waste (HLW) forms [1]. The effect of radiation damage on the structure and consequently on the durability of these phases is important to predictive modelling of their behaviour in the repository environment and risk assessment
The Dependence of the Diffusion Coefficients of 3H and Cs on Grain Size in Compacted Montmorillonite
Authors: Nakajima Mamoru , Kozaki Tamotsu , Kato Hiroyasu , Sato Seichi , Ohashi Hiroshi 
Published: April 2011

ABSTRACTCompacted bentonite is a candidate buffer material in geological disposal of high-level radioactive waste. The transport of radionuclides in compacted bentonite is dominated by diffusion, because of its very low permeability. In this study, we focused on the grain size of clay mineral, which is considered to be closely related to the formation factor in the pore water diffusion model[1,2]. The apparent diffusion coefficients (Da) of HTO and cesium ions in compacted clays were determined using montmorillonite samples with different grain size and dry density, and the effect of the grain size on diffusion behavior was discussed.
Spectral Response and Loss Mechanisms in Amorphous Silicon Solar Cells Determined by Photothermal Deflection Spectroscopy
Authors: Höhne N. , Carius R. , Wagner H. 
Published: April 2011

ABSTRACTA new method to analyse the optical and thermal losses in amorphous silicon solar cells is presented. It is demonstrated that PDS measurements can provide important information on the losses that limit the performance of such cells. The major advantage of the method presented is the ability to determine parameters which are not accessible by other methods, i.e. the reflection, absorption without carrier separation, thermalization and losses in p- and n-layer, field losses, recombination and electrical gain of the solar cell under operating conditions. The method can be applied to thin film solar cells of all kinds complementary to DSR which can also be measured in the same set-up. Eliminating some experimental difficulties could lead to a new comprehensive and complementary characterisation method of solar cells of all kinds.
a-Si:H Thin Film Transistors on Rollable 25-μM Thick Steel Foil
Authors: Ma E.Y. , Wagner S. 
Published: April 2011

ABSTRACTWe report the first amorphous silicon thin film transistors (TFTs) on flexible, ultra-thin substrates of 25 μm thick stainless steel foil. The transistors remain operational under convex or concave bending down to 2.5 mm radius of curvature. Taking advantage of the flexibility and resiliency of these devices, we have successfully fabricated TFTs using only xerographic toner masks printed directly on to the steel substrate and using mechanical alignment in the laser printer to obtain the necessary overlay accuracy. The goal of our work is to develop a foldable active-matrix transistor backplane, at low cost and high throughput, for use in highly rugged and portable applications such as foldable intelligent maps. Our results suggest that such foldable backplane circuits are feasible.
Thin Film Poly-Si Solar Cell on Glass Substrate Fabricated at Low Temperature
Authors: Yamamoto Kenji , Yoshimi Masashi , Suzuki Takayuki , Tawada Yuko , Okamoto Yoshifumi , Nakajima Akihiko 
Published: April 2011

ABSTRACTThe performances of thin film poly-Si solar cells with a thickness of less than 5 μm on a glass substrate have been investigated. The cell of glass / back reflector / n-i-p type Si / ITO is well characterized by the structure of naturally _surface texture and enhanced absorption with a back reflector (STAR), where the active i-type poly-Si layer was fabricated by plasma chemical vapor deposition (CVD) at low temperature. The cell with a thickness of 2.0 μm demonstrated an intrinsic efficiency of 10.7% (aperture 10.1%), the open circuit voltage of 0.539 V and the short current density of 25.8 mA/cm2 as independently confirmed by Japan Quality Assurance. The optical confinement effect explains the excellent spectral response at long wavelength for our cells through the PCID analysis. The higher sensitivity at long-wavelength of our cell appeared in quantum efficiency curves is well correlated to the result of reflectance measurement. The efficiency of 9.3% cell with a thickness of 1.5 pm was proved to be entirely stable with respect to the lightsoaking. Based on the result of various evaluation of diffusion length, it is postulated that the low temperature poly-Si prepared by plasma CVD gives a device quality of poly-Si film.
Optical Properties Of Si Nanocrystals Formed In Si02 By Ion Implantation
Authors: White C. W. , Withrow S. P. , Meldrum A. , Budai J. D. , Hembree D. M. , Zhu J. G. , Henderson D. O. , Prawerttt S. 
Published: April 2011

ABSTRACTSi nanocrystals formed in SiO2 by high-dose ion implantation and annealing give rise to strong optical absorption and intense photoluminescence (PL). The dose dependence of optical absorption provides evidence for size-dependent quantum confinement in the Si nanocrystals. PL peak energies are nearly independent of dose suggesting that surface or interface states play an important role in PL. Estimates of absorption bandgaps in the nanocrystals are given.
Hybrid Amorphous and Polycrystalline Silicon Devices For Large-Area Electronics
Authors: Mei P. , Boyce J. B. , Fork D. K. , Anderson G. , Ho J. , Lu J. , Hack M. , Lujan R. 
Published: April 2011

ABSTRACTDistinct features of amorphous and polycrystalline silicon are attractive for large-area electronics. These features can be utilized in a hybrid structure which consists of both amorphous and polycrystalline silicon materials. For example, an extension of active matrix technology is the integration of peripheral drivers for the improvement of reliability, cost reduction and compactness of the packaging for large-area electronics. This goal can be approached by a combination of amorphous silicon pixel switches and polysilicon drivers. A monolithic fabrication process has been developed based on a simple modification of the amorphous silicon transistor process which uses selective area laser crystallization. This approach allows us to share many of the process steps involved in making both the amorphous and polysilicon devices. Another example of the hybrid device structure is a self-aligned amorphous silicon thin film transistor with polysilicon source and drain contacts. The advantages of the self-aligned transistor are reduction of the parasitic capacitance and scaling down of the device dimension. With a selective laser doping technique, self-aligned and shortchannel amorphous silicon thin film transistors have been demonstrated.
Transistors with a Profiled Active Layer Made by Hot-Wire Cvd
Authors: Meiling H. , Brockhoff A.M. , Rath J.K. , Schropp R.E.I. 
Published: April 2011

ABSTRACTIn order to obtain stable thin-film silicon devices we are conducting research on the implementation of hot-wire CVD amorphous and polycrystalline silicon in thin-film transistors, TFFs. We present results on TFTs with a profiled active layer (deposited at ≥9 Å/s), and correlate the electrical properties with the structure of the silicon matrix at the insulator/semiconductor interface, as determined with cross-sectional transmission electron microscopy. Devices prepared with an appropriate H2 dilution of SiH4 show cone-shaped crystalline inclusions. These crystals start at the interface in some cases, and in others exhibit an 80nm incubation layer prior to nucleation. The crystals in the TFTs with the incubation layer are not cone-shaped, but are rounded off. The hot-wire CVD deposited devices exhibit a high fieldeffect mobility up to 1.5 cm2V−1s−l. Also, these devices have superior stability upon continuous gate bias stress, as compared to conventional glow-discharge α-Si:H TFTs. We ascribe this to a combination of enhanced structural order of the silicon and a low hydrogen content.
Guide for Low-Temperature and High-Rate Deposition of Device Quality Poly-Silicon Films By Cat-Cvd Method
Authors: Heya Akira , Nakata Kazuhisa , Izumi Akira , Matsumura Hideki 
Published: April 2011

ABSTRACTPolycrystalline silicon (poly-Si) films are obtained at temperatures lower than 400°C by catalytic chemical vapor deposition (Catalytic CVD = Cat-CVD) method, often called hot-wire CVD method. Structural properties of the Cat-CVD poly-Si films, deposited with various gas pressures, are studied by Raman scattering spectroscopy and X-ray diffraction technique. It is found that there are two recipes for obtaining device quality poly-Si films, that is, such poly-Si films are obtained at low gas pressure around 1 mTorr or less as already reported, and also at high gas pressure around 0.1 to 1 Torr. It is also found that, in addition to catalyzer temperature, the gas pressure is a key factors to obtain device quality poly-Si films at high deposition rates.
Recent Progress of Low Temperature Poly Si Tft Technology
Authors: Yoneda Kiyoshi 
Published: April 2011

ABSTRACTSince being introduced to the production line in 1996, replacing the first generation a-Si TFT line, low-temperature poly-Si production technology aimed at manufacturing small and medium size LCD products has improved steadily corresponding to customers' requirements for rapid growth of the DVC and DSC markets. In the future, this production technology must progress to actual industry technology levels in order to cope with production applied not only to large size displays, which have a major market share in the present display market, but also to a large glass substrate, which effectively cuts the cost of products, although improvement of production yield and productivity in terms of pursuing cost reduction must be proceeded.This paper has described existing problems of inherent low-temperature poly-Si TFT processes and their relating additional processes in present production methods. We have also discussed updating production technologies. To cope with production for a large size display, it is necessary to establish fabrication technology of higher performance TFTs with electron mobility larger than 200cm2/V·s. We believe that one key technology is to fabricate a large-scale and highly-uniform recrystallized poly-Si film with smooth surface morphology as well as precisely-controlled grain size in production. To cope with production using a large glass substrate, it is essential to develop ELA equipment with laser power greater than 200W.
Fluorinated Silicon Nitride Film Deposited at Low Temperatures from SiH4-SiF4-NH3
Authors: Park Y.-B. , Rhee S. , Choi J.-H. , Kimb C.-W. , Suok J.H. 
Published: April 2011

ABSTRACTThe effect of SiF4 addition on the deposition characteristics and film property has been studied for the improvement of long term stability of the SiNx:F film in TFT applications. During the deposition with SiF4 addition, atomic hydrogen species in the gas phase significantly decreased. A detailed bonding configuration of fluorine and hydrogen was investigated by XPS and FT-IR. Optical band gap increases with the increment of fluorine concentration in the film. High compressible stress turned to low tensile stress with increasing SiF4 flow rate. The breakdown strength and barrier height for the conduction of trapped electron were improved by SiF4 addition even in Si-rich SiNx:H films due to the stable Si-F bond formation.
The Structural Evolution of A-SI:H Films Prepared by Pulse Rf Power Modulation with Hydrogen and Helium Dilution
Authors: Jiang Yeu-Long , Lee Min-Chang , Chen Shieng-Huai 
Published: April 2011

ABSTRACTA-Si:H films were deposited in a PECVD system using 5k to 5 Hz and 25 to 75% duty cycle square-wave pulse modulation RF power and with 80% hydrogen or 80% helium dilution. The transmission and the microstructure of the hydrogen bonding configuration were measured using NIR-VIS-UV and FTIR spectrometers. The powder formation in the reactor chamber was low for a deposition rate less than 5.87 nm/min and was completely suppressed by the 500 Hz pulse RF power with a duty cycle less than 33.3%. The low microstructure R ratio is the result of the reduction of the polymization reaction in the plasma for a low deposition process. A R ratio less than 14% could be obtained using 500 Hz with a duty cycle less than 33.3% for helium dilution or using 5k to 50 Hz with a duty cycle less than 50% for hydrogen dilution. The refractive index of the films is high for the films with low R ratio. The more compact and higher quality films exhibit greater SiH bonding configurations in the a-Si:H films.
High Deposition Rate Amorphous Silicon Solar Cells and Thin Film Transistors Using the Pulsed Plasma Pecvd Technique
Authors: Morrison Scott , Xi Jianping , Madan Arun 
Published: April 2011

ABSTRACTThe pulsed plasma technique has been shown to increase the deposition rate without an increase in the particulate count in the plasma which is an important factor determining the yield of commercial products such as active matrix displays. In this paper, we report the deposition of amorphous silicon at deposition rates of up to 15 Å/sec, using a modulation frequency in the range of 1-100kHz. These materials have been incorporated into a simple p/i/n solar cell and thin film transistor (TFT) configurations. We report on the effect of the conversion efficiency as a function of the modulation frequency, which in turn is related to the deposition rate. We also report on the TFT performance with modulation frequency and compare the results with devices made under the conventional continuous wave PECVD plasma at 13.56MHz.
Molecular Hydrogen in Hot-Wire Hydrogenated Amorphous Silicon
Authors: Liu Xiao. , Iwaniczko E. , Pohl R.O. , Crandall R.S. 
Published: April 2011

ABSTRACTWe have studied the elastic properties of hydrogenated amorphous silicon (a-Si:H) prepared by hot wire chemical-vapor deposition (HWCVD). With 1 at.% H, this material has been found to be the only amorphous solid which has a low-temperature internal friction more than two orders of magnitude smaller than all other amorphous solids studied to date, as reported recently. As the hydrogen concentration increases above 1 at.%, a broad relaxation peak in internal friction around 5 K is observed. Even more striking is an extremely narrow peak in internal friction accompanied by a discontinuous change in the sound velocity at 13.8 K, which coincides with the triple point temperature of molecular hydrogen. Evidences are provided to show that this anomaly is caused by bulk molecular hydrogen which undergoes a liquid-solid phase transition. This is the first observation for the existence of bulk H2 in HWCVD a-Si:H.
Hydrogen'S Effect on Stability of Undoped A-Si:H Under Light Soaking
Authors: Golikova O.A. , Kazanin M.M. , Kuznetsov A.N. , Kudoyarova V.Kh. , Adriaenssens G.J. , Grevendonk W. , Eliat A. 
Published: April 2011

ABSTRACTLight-soaking kinetics of photoconductivity at room temperature for undoped a-Si:H films deposited by rf-plasma enhanced chemical vapor deposition and by dc-magnetron assisted decomposition at T8 = 300 and 350°C have been investigated. The rate of degradation has been expressed by the value of exponent of the power law: σph∼t−y. The hydrogen content in the films, the type of Si-H bonds and their contribution as well as the Fermi level position were controlled by changes in the deposition conditions. Hydrogen's effect on the y value was shown for the different cases. The films, having γ=0, were identified.
Electron and Hole Transient Currents in Hydrogenated Amorphous Silicon and Some Alloys Measured by The Photoconductive Time-of-Flight Technique
Authors: Eliat Astrid , Adriaenssens Guy , Yan Baojie 
Published: April 2011

ABSTRACTA series of pure hydrogenated amorphous silicon (a-Si:H) samples as well as carbon (aSi:C:H) and sulfur alloys (a-Si:S:H) were investigated by means of the photoconductive time-of-flight technique. Drift moblility (µd) measurements reveal a fast decrease of the electron µd upon C or S addition, while the hole µd does not change significantly. Contrary to the electron transients, hole transient currents do not show the typical space-charge-limited (SCL) features, even for high light intensities where these features are normally seen. SCL features are observed to disappear for electron transients as well in the a-Si:H alloys with increasing alloy content. Above results are all explained starting from the a-Si:H density of states (DOS) model where the valence band (VB) tail is much broader than the conduction band (CB) tail. Introducing additional disorder by alloying broadens both the VB and the CB tails while the relative increase of the CB tail is much greater than that of the VB tail.
Microscopic Nature of Nature Light Induced Defects
Authors: Biswas R. , Pana B. C. 
Published: April 2011

ABSTRACTMolecular dynamics simulations find light-induced metastable defects to be silicon dangling bonds accompanied by (Si-H)2 defect complexes that have two Si-H bonds. These complexes are formed by pairs of hydrogen breaking a silicon bond. This supports the model of Branz. These defects are the analogue of the H2* defect in c-Si and their energy correlates with the bond-angle strain. Several features of annealing including E-field induced effects are well accounted for by the (Si-H)2 defect.
Concentration Dependence of Hydrogen Diffusion in Hydrogenated Silicon
Authors: Beyer W. , Zastrow U. 
Published: April 2011

ABSTRACTThe concentration dependence of hydrogen diffusion was studied in hydrogenated crystalline and amorphous silicon prepared by hydrogen implantation into crystalline Si wafers and into amorphous silicon of low hydrogen concentration. The results are compared with data for plasma-grown a-Si:H and µc-Si:H films. The increase of the diffusion coefficient with rising hydrogen concentration in a-Si:H is explained by an (equilibrium) energy band model of hydrogen diffusion whereas the decrease of the diffusion coefficient in c-Si:H is explained by a trapping model. The different behavior is attributed to a greater flexibility of the amorphous Si network compared to the crystalline Si lattice which is also visible in a difference in hydrogen-related microstructure formation.
Degradation Kinetics of Hydrogenated Amorphous Silicon: The Effect of Embedded Microcrystallites
Authors: Lubianiker Yoram , Cohen J. David , Jin Hyun-Chul , Abelson John R. 
Published: April 2011

ABSTRACTWe have studied the degradation kinetics of undoped a-Si:H films which contain a significant fraction of silicon microcrystallites. The degradation rate is found to be exceptionally slow in the first stage of degradation, then the defect density follows the “normal” t1/3rate and finally saturates. We present a model which relates this abnormal kinetics to the microcrystallites which are embedded in the amorphous matrix.
Analysis of Drain Currents During Switching off a-Si:H Based Thin Film Transistors
Authors: Lemmi F. , Street R. A. 
Published: April 2011

ABSTRACTWe present measurements and analysis of a-Si:H thin film transistor (TFT) transients when the gate voltage switches the device from a conducting to a non-conducting state. The drain current transient has been monitored in the medium-long (Ims-100s) time range and exhibits a power law decay extending to at least 10 seconds. The decay has been studied over a range of drain voltages and gate off-state voltages. Measured data show that the gate off-state can help to obtain a low drain leakage current at long times when high drain voltages are being used.However, the decay at low drain voltages shows little sensitivity to different gate off-state voltages. An analytical model is developed, based on the relaxation of the Fermi level toward mid-gap in a spatially uniform TFT channel. The model shows how deep defects are responsible for the current decay slope at long times, while shallower states determine the slope in the short time range. An energy-independent defect density would produce a 1/t slope for the current decay. Shallow states and deep states affect in opposite ways the slope since their density is energydependent in opposite ways as Fermi level moves deeper into the band-gap. Furthermore, long decay times are associated with a wider depletion region in the channel and increase the total number of defect states involved. A steeper decay than 1/t is expected and observed for shorttime ranges, while a more gradual (about 1/t1/2) one corresponds to long time measurements. The implications of the transient decay for the performance of active matrix arrays will be discussed.
Paramagnetic Defects in Undoped Microcrystalline Silicon Deposited by the Hot-Wire Technique
Authors: Kanschat P. , Lips K. , Brüggemann R. , Hierzenberger A. , Sieber I. , Fuhs W. 
Published: April 2011

ABSTRACTWe report on a study of ESR and conductivity on a series of hot-wire CVD microcrystalline silicon samples prepared with different hydrogen dilution of silane. We observe two different types of dangling bond defects in ESR in different microscopic environments. One type of defect is located at outer surfaces accessible to oxygen and/or chemicals, the other is located at inner boundaries presumably at columnar structures. We correlate changes of the defect density induced by either annealing, exposure to air or wet-chemical treatment with the morphology and electronic properties of the films. We find that annealing at 200 °C induces irreversible changes in donor concentration as monitored by an ESR signal at g = 1.9981±3.
Excitation Intensity Dependence of Light-Induced Electron Spin Resonance in Hydrogenated Amorphous Silicon Films
Authors: Yan Baojie , Taylor P. C. 
Published: April 2011

ABSTRACTLight-induced electron spin resonance in a-Si:H films was measured using second harmonic detection over a wide range of excitation intensities. Second harmonic detection results in an undifferentiated absorption lineshape that saturates much less easily with increasing microwave power. The ratio of the spin densities of the broad line to the narrow line is approximately 3 at a generation rate of 1019 cm−3s−1, and this ratio increases only slightly with decreasing excitation intensity. The kinetics of the LESR after the light is turned on or off show dispersive behavior. The dispersive response of the LESR is related to the dispersive transport of carriers at low temperature. A model that assumes a bimolecular recombination fits the experimental results reasonably well.