bluuebunny/crossref_metadata_2025_split huggingface dataset:
Voltage Dependent Carrier Collection in CdTe Solar Cells
Authors: Bätzner D.L. , Agostinelli Guido , Romeo A. , Zogg H. , Tiwari A.N. 
Published: April 2011

ABSTRACTThe measurement of quantum efficiency with bias voltage is a powerful tool to characterize CdTe/CdS solar cell. As the quantum efficiency changes drastically with bias it will be referred to as Apparent Quantum Efficiency AQE. The AQE gives insight to the spectral contents of the cell current and therefore resolves the spatial carrier collection in the cell at each working point. So it is possible to understand the influence of the junctions and changing resistances in the cell. The photoconductivity of CdS facilitates AQE well above unity, i.e. up to 100, at high forward bias. The spectral sensitivity of the CdS photoconductivity affects the cell current strongly. This can explain the dependence of fill factor and roll-over of the I-V characteristics on the spectral content of illumination. Further more back contact junction influence and defect related features, such as sub band gap generation, are evident in the AQE for high forward bias.
Interface Defects in GIGS-based Solar Cells from Coupled Electrical and Chemical Points of View
Authors: Canava B. , Vigneron J. , Etcheberry A. , Saad S. Ould , Djebbour Z. , Mencaraglia D. , Guillemoles J.F. , Lincot D. 
Published: April 2011

ABSTRACTChemistry of co-evaporated CIGS surfaces submitted to chemical treatments relevant to fabrication steps were investigated by XPS and admittance spectroscopy. A Se XPS signal specific of the CIGS surfaces was identified. Surface states seen by Admittance and surface chemistry are seen to change significantly during the elaboration steps. Consequences for device elaboration are briefly discussed.
Absorption and photoluminescence studies of lightly alloyed CdTe(S) and CdS(Te)
Authors: Shvydka Diana , Compaan A.D. , Price K.J. 
Published: April 2011

ABSTRACTCdTe-rich and CdS-rich alloy films were deposited at temperatures less than 300C using an rf sputtering technique. Transmission-reflection and photoluminescence measurements were conducted to study the near-band edge properties of this ternary system for films of different compositions at room temperature and at 10K. Results were compared to data on defect states introduced in CdTe single crystal by annealing at several different overpressure conditions, including CdS and CdCl2 overpressures. A below-band-gap photoluminescence excitation technique was used to study systematically the effect of different steps in the production of the complete solar cell on band gap states of CdSxTe1−x alloys as well as pure binary constituents.
Current Transport in CuInS2 Solar Cells Depending on Absorber Preparation
Authors: Reiβ Joachim , Malmström Jonas , Werner Axel , Henge Imke , Klenk Reiner , Lux-Steiner Martha Ch. 
Published: April 2011

ABSTRACTAccording to our model for the current transport in CuInS2/CdS/ZnO solar cells presented previously, the dominant recombination under illumination occurs at the CuInS2/CdS interface. In this contribution we expand this model for cells where the absorber has been prepared in different sequential processes by using results from jV curve measurements performed at varied temperature and illumination. We find that in contrast to CuInSe2 and CuGaSe2 solar cells from the Ångström Solar Center the CuInS2 cells exhibit a qualitative change in the dominant recombination mechanism between the dark and under illumination. The dominant recombination mechanism under illumination appears to be affected by absorber preparation parameters.
Alternating Layer Chemical Vapor Deposition (ALD) of Metal Silicates and Oxides for Gate Insulators
Authors: Gordon Roy G. , Becker Jill , Hausmann Dennis , Suh Seigi 
Published: April 2011

ABSTRACTA new process was developed for deposition of the silicates and oxides of metals such as zirconium and hafnium at low substrate temperatures (100–300°C). The silicon and oxygen source is tris(tert-butoxy)silanol, (tBuO)3SiOH, and the metal precursors are metal amides. A typical reaction isZrL4 + 2 (tBuO)3SiOH → ZrSi2O6 + 4HL + 6H2C=C(CH3)2 + 2 H2Oin which the ligand L is ethylmethylamide, -NEtMe. The precursor vapors were alternately pulsed into a heated reactor, yielding about 0.3 to 0.7 nm of metal silicate film for each cycle. Replacing the silanol pulses with water pulses yields pure metal oxides with a thickness of about 0.1 to 0.15 nm per cycle. The silicon content of the films can be adjusted to any desired value by replacing some of the silanol pulses by water pulses. This new process has a number of advantages over previous methods for depositing metal silicates. Uniformity of thickness and stoichiometry are readily achieved. The deposition atmosphere is non-oxidizing, so that formation of low-k interfacial oxides between the deposited layer and a silicon substrate is minimized. The new halogen-free precursors avoid halogen contamination of films and corrosion of deposition systems. This process is a promising method for forming the next generation of ultra-thin high-k gate dielectrics in silicon-based microelectronics.
Promising Gate Stacks with Ru & RuO2 Gate Electrodes and Y-silicate Dielectrics
Authors: Zhong Huicai , Heuss Greg , Suh You-Seok , Hong Shin-Nam , Misra Veena , Kelly Jason , Parsons Gregory 
Published: April 2011

ABSTRACTIn this work, we studied the electrical and thermal stability of Ru and RuO2 electrode on Y-silicate dielectrics in contrast to ZrO2 and Al2O3 dielectrics. Very low resistivity Ru and rutile stoichiometric RuO2 films, deposited via reactive sputtering, were evaluated as gate electrodes on ultrathin Y-silicate, ZrO2 and Al2O3 films for Si-MOS devices. Thermal and chemical stability of the electrodes was studied at annealing temperatures up to 800°C in N2 and subsequently forming gas anneal. XRD and XPS were measured to study grain structure and interface reactions. The morphology of the films was tested by atomic force microscopy (AFM). Electrical properties were evaluated via MOS capacitors. The role of oxygen inside dielectrics was studied by comparing equivalent oxide thickness change as a function of annealing temperature for capacitors with Y-silicate, ZrO2and Al2O3 dielectrics. Good stability of Ru and RuO2 gate electrodes on all dielectrics studied was found. Flatband voltage and gate current as a function of annealing temperature was also studied. It was found that capacitors with Y-silicate after high-temperature anneal had less positive flatband voltage shift than ZrO2 and Al2O3. For capacitors with Ru gate electrode, the significant flatband voltage shift after high temperature anneal could be partially removed by a forming gas anneal.
Effect of Pre-cooling Treatment on the Formation of C54 Phase Titanium Silicide
Authors: Zhangand Lin , Lee YongKeun 
Published: April 2011

ABSTRACTIn this paper, the effect of pre-cooling treatment on the low resistivity C54 phase titanium silicide film growth was investigated. Our experimental results and micro-structural analysis show that, by introducing such cooling treatment into the titanium silicide process to precede the conventional rapid thermal annealing, the low resistivity C54 phase formation can be enhanced. Defects at the Si/Ti interface caused by the thermal mismatch between titanium and silicon layers during the cooling treatment were found to contribute to the increase of the C49 nucleus sites. This help to supply more C49 grain boundaries and triple junction sites at which the C54 phase could nucleate. This discovery has the potential to reduce the complexity and cost associated with forming low resistivity titanium silicide on sub-micron structures for future ULSI application.
Molybdenum Gate Electrode Technology For Deep Sub-Micron CMOS Generations
Authors: Ranade Pushkar , Lin Ronald , Lu Qiang , Yeo Yee-Chia , Takeuchi Hideki , King Tsu-Jae , Hu Chenming 
Published: April 2011

ABSTRACTContinued scaling of CMOS technology beyond the 100 nm technology node will rely on fundamental changes in transistor gate stack materials [1]. Refractory metals and their metallic derivatives are among the only candidates suitable for use as transistor gate electrodes. In earlier publications, Mo has been proposed as a potential candidate for use as a MOSFET gate electrode and the implantation of nitrogen ions into the Mo film has been observed to lower the interfacial work function of Mo [2,3]. This observation indicates the potential application of Mo as a CMOS gate electrode. In this paper, the dependence of the interfacial work function on the nitrogen implant parameters (viz. energy and dose) is discussed. In general, metal work functions at dielectric interfaces depend on the permittivity of the dielectric [3,4,5]. This dependence of the gate work function on dielectric permittivity presents a significant challenge for the integration of metal gate electrodes into future CMOS technology. In light of this, the ability to engineer the Mo gate work function over a relatively large range makes it an attractive candidate for this application.
Silicide Formation for Ni and Pd Bilayers on Si(100) Substrates
Authors: Qu Xin-Ping , Detavernier C. , Van Meirhaeghe R. L. , Cardon F. 
Published: April 2011

ABSTRACTThe silicide formation for Ni/Pd and Pd/Ni bilayers on Si(100) substrates was investigated. X-ray diffraction and photoelectron spectroscopy (XPS) depth profiling have been applied to study the phase formation of the silicide. We found that with addition of Pd into Ni/Si, a uniform layer of ternary Ni1−xPdxSi layer formed and kept stable for a wide temperature range. The lattice parameter of Ni1−xPdxSi as a function of Pd addition was calculated. The nucleation temperature of NiSi2 was delayed due to the addition of Pd. The higher the Pd addition, the larger the increase in NiSi2 nucleation temperature. We also studied the effect on the addition of Ni to the Pd/Si reaction. For pure Pd/Si reaction PdSi nucleated from Pd2Si at 750°C or above. For Ni/Pd/Si reaction, Pd2Si changed to Ni1−xPdxSi at temperature lower than 750°C due to the incorporation of Ni. The phenomena were explained by classic nucleation theory taking into account the effect of mixing entropy effect.
“Reverse” Stress Relaxation in cu Thin Films
Authors: Spolenak R. , Volkert C. A. , Ziegler S. , Panofen C. , Brown W.L. 
Published: April 2011

ABSTRACTIn this study we present investigation on the anelastic behavior of sputtered 1 [.proportional]m thin Cu films. Most of the literature that reports on the mechanical properties of thin metallic films is based on substrate curvature measurements. We have developed a new version of a bulge tester that combines the capacitive measurement of the bulge deflection of a membrane with a resonance frequency measurement of the residual stress in the membrane. A Cu membrane is plastically deformed to a pre-determined strain by controlled gas-pressure bulging of the membrane. After the bulging stress is removed, the residual tensile stress, which has been decreased by the plastic deformation, is then determined by measuring the resonant frequency as a function of time. Immediately after plastic straining, the residual (tensile) stress of membranes was observed to increase. At room temperature a maximum stress was typically reached in the order of an hour. At still longer times the stress decreased again as a result of creep. The transient increase in stress following plastic straining grew larger as the amount of plastic strain produced by bulging was increased. With higher temperatures the transient became both faster and larger. A model is presented that based on the mechanism of thermally activated glide separates the microstructure in a class of “soft” and “hard” grains solving the issue of an “apparent” increase in strain energy as a function of time after deformation.
Optical study of SiGe films grown with low temperature Si buffer
Authors: Luo Y. H. , Wan J. , Liu J. L. , Wang K. L. 
Published: April 2011

ABSTRACTIn this work, SiGe films on low temperature Si buffer layers were grown by solid-source molecular beam epitaxy and characterized by atomic force microscope, photoluminescence and Raman spectroscopy. Effects of the growth temperature and the thickness of the low temperature Si buffer were studied. It was demonstrated that using proper growth conditions of the low temperature Si buffer, the Si buffer became tensily strained and gave rise to the compliant effect. High-quality SiGe films with low threading dislocation density have been obtained.
X-Ray Diffuse Scattering from Misfit Dislocation at Buried Interface
Authors: Li Kaile , Miceli Paul F. , Lavoie Christian , Tiedje Tom , Kavanagh Karen L. 
Published: April 2011

ABSTRACTMotivated by x-ray scattering experiments on heteroepitaxially grown thin films, we present model calculations of the diffuse x-ray scattering arising from misfit dislocations. The model is based on the elastic displacements from dislocations whose positions are spatially uncorrelated. These numerical results give support to a phenomenological model [Phys. Rev. B 51, 5506 (1995)] that predicts the scaling of diffuse scattering intensity with perpendicular wavevector, Qz. At low Qz the diffuse width scales inversely with the defect size, which is given by the film thickness due to the effect of the elastic image field, whereas at high Qz the diffuse width is mosaic-like, scaling with Qz. New experimental results for InxGa1−xAs/GaAs are also presented and compared to the model. The calculations are in good agreement with these experiments, as well as other measurements in the literature for high and low dislocation density.
Si/GaAs heterostructures fabricated by direct wafer bonding
Authors: Dragoi Viorel , Alexe Marin , Reiche Manfred , Radu Ionut , Thallner Erich , Schaefer Christian , Lindner Paul 
Published: April 2011

ABSTRACTSi/GaAs heterostructures were obtained by a low temperature direct wafer bonding (DWB) method which uses spin-on glass (SOG) intermediate layers. The use of intermediate SOG layers allows the fabrication of Si/GaAs heterostructures at processing temperatures lower than 200°C. The achieved bonding energy permits thinning down to a few microns of Si and GaAs wafers, respectively, using grinding procedures followed by chemical mechanical polishing (CMP). After thinning, the heterostructures sustained annealing temperatures of 450°C without damaging of the bonded interface. The above bonding procedure was successfully applied for bonding GaAs wafers to Si wafers with structured surfaces. A technology was developed based on this bonding method for producing universal GaAs-on-Si or Si-on-GaAs substrates.
Multiple Wafer Bonding for MEMS Applications
Authors: Reiche M. , Haueis M. , Dual J. , Cavalloni C. , Buser R. 
Published: April 2011

ABSTRACTMost of the microelectromechanical systems (MEMS) require a 3-dimensional architecture which can efficiently be realized by multiple semiconductor wafer direct bonding. The present paper demonstrates the method on a force sensor for high resolution measurements of static loads. To minimize temperature stress an all-in silicon solution was developed in contrast to micromachined resonant force sensors published already in the literature.The presented force sensor integrates load coupling, the excitation and detection of the vibration of the microresonator in one and the same single crystal silicon package. First measurements proved a sensitivity of 26 Hz/N and a resolution better than 3 mN.
Numerical Modeling of High Repetition Rate Pulsed Laser Crystallization of Silicon Films on Glass
Authors: Köhler Jürgen R. , Dassow Ralf , Werner Jürgen H. 
Published: April 2011

AbstractThis contribution investigates the crystallization behavior of amorphous silicon films on glass by using pulsed lasers with very high repetition rates up to 100 kHz. We determine the influence of the laser repetition rate f and of the film thickness d on the grain width g of the resulting polycrystalline silicon films. Our experimental results indicate a strong dependence of the grain width g on film thickness d as well as on the repetition rate f of the laser. The grain width rises from g = 0.27 µm to g = 3.59 µm if the film thickness increases from d = 50 nm to d= 300 nm and the repetition rate f from f = 20 kHz to 100 kHz. We use a purpose developed two- dimensional finite difference numerical model to calculate the evolution of the temperature in the silicon film and in the glass substrate. An increase of both, the film thickness d, and the repetition rate f decrease the solidification velocity v of the film. A comparison of the solidification velocity vs and the measured grain width g shows a linear correlation.
(001)-Textured Laser-Crystallized Silicon thin Films on Glass Substrates
Authors: Nerding M. , Christiansen S. , Esser G. , Urmoneit U. , Otto A. , Strunk H.P. 
Published: April 2011

AbstractWe investigate the microstructure of polycrystalline silicon films (grain size, texture and grain boundary population) on glass substrates. These films are produced from amorphous silicon precursor layers by scanning the raw beam of a continuous wave Ar+- ion laser operated at a wavelength of 514 nm over the amorphous silicon thereby crystallizing it. The materials applicability for devices in large area electronics strongly depends on the orientation of the surface normal, the average grain size and the defect density and population. Transmission electron microscopy together with electron back-scattering diffraction analysis of the crystallized layers reveal grain widths of about 10μm and grain lengths of several 10 μm. Under certain procesing conditions a preferred (001)-surface normal orientation (texture) forms. The grain boundary population is dominated in the textured films by coincidence boundaries, essentially twin boundaries of first and second order as well as Σ=5 boundaries.
Single-Crystal Thin Film Transistor by Grain-Filter Location-Controlled Excimer-Laser Crystallization
Authors: Dijk Barry D. van , Wilt Paul Ch. Van der , Bertens G. J. , Nanver Lis.K. , Ishihara Ryoichi 
Published: April 2011

AbstractThin film transistors (TFTs) are fabricated inside a large, location-controlled, silicon grain, fabricated with the grain-filter method. In a first experiment TFTs with high field-effect mobility for electrons of 430 cm2/Vs are fabricated. The off-current and subthreshold swing have high values of 60 pA and 1.2 V/dec, respectively. The grain-filter is improved by doping the channel and by planarizing the grain-filter by chemical mechanical polishing (CMP). TFTs fabricated in CMP-planarized grain-filters have mobility, off-current, and subthreshold swing of 430 cm2/Vs, 0.3 pA, and 0.29 V/dec, respectively, which compares well with the characteristics for SOI TFTs.
High Quality Poly-Si Film and Transistor Formed by Nickel-Induced- Lateral-Crystallization and Pulsed-Rapid-Thermal-Annealing
Authors: Leung T.C. , Cheng C.F. , Poon M.C. 
Published: April 2011

AbstractNickel Induced Lateral Crystallization (NILC) and Pulsed Rapid Thermal Annealing (PRTA) have been used to study new low temperature and high quality poly-silicon (poly-Si) films and thin film transistors (TFTs). The growth rate of poly-Si films has been found to greatly increase from 0.025μm/minute to 1.07μm/minute, and the drain current and performance of TFTs have increased by around 75%. The new poly-Si technology has good potential to apply in high performance, large area, fast throughput, low cost and even low temperature device applications.
Study of Crystal Growth in Grain-Filters for Location-Controlled Excimer Laser Crystallization
Authors: Wilt Paul Ch. van der , Dijk B.D. van , Bertens G.J. , Ishihara R. 
Published: April 2011

AbstractAmorphous silicon films were transformed into large-grain polycrystalline silicon films by excimer laser induced rapid melting and solidification. Growth is seeded by residual unmolten silicon left in a grid of holes made in the underlying silicon oxide layer. Growth thus starts with a vertical growth phase, during which occlusion of grains occurs, ideally filtering out only a single grain that subsequently seeds the lateral growth. Yield was increased by sharpening the edges of the hole to improve the filtering mechanism and very uniform polycrystalline layers were obtained. Furthermore, simulations were performed to analyze parameters such as growth velocity and melt depth. It was found that heat from laser light absorbed in the neighborhood of the hole strongly contributes to melt depth and thus to the filtering mechanism. Substrate heating or longer pulse durations can be utilized to ensure the occlusion of grains during vertical growth, to reduce thermal stresses, and to increase grain size to a value sufficient for single crystal thin-film transistors.
The Study of the Formation of Thin SOI Structure by SIMOX with Water Plasma
Authors: Jing Chen , Meng Chen , Xiang Wang , Yemin Dong , Zhihong Zheng , Xi Wang 
Published: April 2011

AbstractThe biggest drawback of the widely application of SIMOX-SOI material is the low yield and the high cost which mainly due to the long implantation time by conventional beamline implanter. An implanter without an ion mass analyzer is used to fabricate SOI materials by H2O+, HO+, and O+ ions implantation using water plasma. Based on the consideration that the masses of the three ions of are quite close, their depth profiles in as-implanted wafers will not disperse much, which makes it possible for the formation of a single buried oxide layer by choosing the appropriate energy and dose. The results show that it exits a dose window at fixed implantation energy to form desirable thin or ultra-thin SOI structure with the buried oxide layer free of silicon islands. Compared to conventional SIMOX method, the sample implanted at the same dose and energy has thicker BOX layer. This probably caused by the heavy oxygen damaged region with hydrogen-induced defects in as-implanted wafer appears to be the adsorption center for the outside oxygen to diffuse into the silicon during the high-temperature annealing process.
Experimental Study on the Role of Hydrogen in the Breakdown of Low-Temperature Si Epitaxy
Authors: Platen-Schwarzkopf J. , Bohne W. , Fuhs W. , Lips K. , Röhrich J. , Selle B. , Sieber I. 
Published: April 2011

AbstractHomoepitaxial Si layers were grown on Si(100) at temperatures of 325 - 500 °C by Electron-Cyclotron Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR PECVD) from a gas mixture of SiH4,H2 and Ar. Ar was added in order to realize high growth rates where the breakdown of epitaxy was well observed. Si disorder depth profiles derived from RBS channeling spectra were compared with hydrogen depth distributions measured by Heavy-Ion Elastic Recoil Detection Analysis (HI-ERDA) and Secondary Ion Mass Spectroscopy (SIMS). The results suggest that the transition from epitaxial to amorphous growth proceeds through two stages: (1) a highly defective but still ordered growth with the defect density increasing as the growth proceeds and (2) the formation of conically shaped precipitates of amorphous Si. Both regions act as an increasingly effective sink for excessive hydrogen which diffuses from the growth surface into the bulk of the sample. In perfectly grown epitaxial films, where the overall concentration of excessive hydrogen was low, the hydrogen diffusion tail was found to extend far beyond the interface into the Si substrate.