bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel ‘Photochemical deposition’ and conventional ‘Electrochemical deposition’ of CdS and HgxCd1−xTe thin films and their characterization for solar cell device applications
Authors: Kumaresan R. , Ichimura M. , Babu S.Moorthy , Ramasamy P. 
Published: April 2011

ABSTRACTSolar cell devices of the structures CdS/CdTe and CdS/HgCdTe, based on II-VI semiconductor thin films have been fabricated and analyzed. CdS thin films were deposited by the recently established novel deposition technique, namely, 'Photochemical deposition' and the Cd rich HgxCd1−xTe films used for the device fabrication were deposited by the conventional ‘electrochemical deposition’ technique. First solar cell devices of the structures CdS/CdTe and CdS/HgCdTe using photochemically deposited CdS films, were fabricated and analyzed for the conversion efficiency.
Design, Actual Performance, and Electrical Stability of CISCuT-Based Quasi-Endless Solar Cell Tapes
Authors: Winkler Michael , Penndorf Jürgen , Griesche Joachim , Konovalov Igor , Tober Olaf 
Published: April 2011

ABSTRACTSolar cells based on Cu-In-S-phase absorber layers on a quasi-endless copper tape were made in a series of consecutive roll-to-roll processes, for which a base line has recently been set up. The so called “as grown cell absorber”, which consists of a stack of CuIn5S8 and CuInS2 layers, is completed to a solar cell by a CuI buffer layer of about 70 nm thickness and a 1 μm thick ZnO-TCO window layer. The design of the whole cell including the phase constitution of the absorber layer and the actual standard electrical characteristics will be presented. Considering the first stability tests and the experimental possibilities of the base line, an outlook will be given concerning the ability and perspectives of using these cell tapes for module production.
Influence of atomic hydrogen on intrinsic defects in CuInSe2
Authors: Otte Karsten , Lippold Gerd , Frank Wilfried , Wenzel Axel , Krauser Johann , Weidinger Alois , Schindler Axel 
Published: April 2011

ABSTRACTHydrogen with an energy of 300 eV was implanted into single crystalline CuInSe2samples at temperatures of 200 °C and 300 °C during implantation. We found that the hydrogen is not limited to the expected implantation depth but diffuses into the bulk of the sample. The hydrogen concentration ranges from 1019H/cm3in a depth of about 300 nm up to some 1021H/cm3next to the surface and resembles a diffusion profile. The hydrogen induced change of composition was not only at the surface, but also up to a depth of about 200 nm similar to that of the hydrogen profile. Mainly a Cu deficiency after hydrogen implantation could be observed and is explained as the passivation of VCuby hydrogen and the additional production of VCuby the induced band-bending.
Effect of CdTe thickness reduction in high efficiency CdS/CdTe solar cells
Authors: Gupta Akhlesh , Matulionis I. , Drayton J. , Compaan A.D. 
Published: April 2011

ABSTRACTHigh efficiency CdTe solar cells are typically grown with CdTe thicknesses from 3 to 15 μm, although the thickness required for 90% absorption of the incident irradiation at 800 nm is only ∼1 μm. In this paper, we present the effect of CdTe thickness reduction on the performance of CdS/CdTe solar cells in which both the CdS and CdTe films were grown by sputtering. We produced a series of cells with different CdTe thickness (from 0.5 to 3.0 μm), and held the CdS thickness and back-contact-processing constant. The effect of CdTe thickness reduction on the diffusion of CdS into CdTe was studied using optical absorption and x-ray diffraction techniques. Only slight decreases occur in open-circuit voltage, short-circuit current, and fill factor with decrease in CdTe film thickness to 1.0 μm. Almost 10% efficient cells were obtained with 1 μm CdTe. Below 1 μm, all cell parameters decrease more rapidly, including the red quantum efficiency.
Importance of electron current in p-type CdTe in CdS/CdTe thin film solar cells at forward bias
Authors: Beier Jutta , Köntges Marc , Nollet Peter , Degrave Stefaan , Burgelman Marc 
Published: April 2011

ABSTRACTIn previous work [1,2], we modeled the cross-over of the I-V curves of thin film CdS/CdTe solar cells in terms of an electron (minority carrier) current in the vicinity of the back contact. In this work, we focus on the necessary extension of this analytical model based on a series of measurement results. Especially the wavelength and voltage dependence of the current at forward bias is illustrated in these measurements. The various possible causes for this kind of behavior are discussed and modeled. The extensions to the previous model, needed to describe the voltage and wavelength dependent behavior of I-V curves of real CdTe/CdS solar cells, are proposed.
Characterisation of TiO2films grown at low temperatures for alternative gate dielectric application
Authors: Zhang Jun-Ying , Boyd Ian W. 
Published: April 2011

ABSTRACTIn this paper we report the growth of thin titanium oxide films on Si (100) and quartz at low temperatures (≤350°C) by photo-induced chemical vapor deposition (photo-CVD) with 222 nm UV radiation using a novel injection liquid source, which overcomes the reproducible problem in conventional bubblers. The properties of the films formed have been studied using ellipsometry, UV spectrophotometry and Fourier transform infrared spectroscopy (FTIR) measurements. Nanostructured films were observed by atomic force microscopy (AFM). It was found that crystalline TiO2films could be formed at deposition temperatures as low as 210°C by x-ray di ffraction (XRD). The influence of the deposition temperature on the film is discussed. The refractive index as high as 2.5 can be obtained at a deposition temperature of 350°C, while an optical transmittance of between 80-95% in the visible region of the spectrum was obtained at different deposition temperatures. Physical and optical characterization both reveal good film qualities, rendering this technique promising for a wide range of industrial application in low temperature microelectronic and optoelectronic material processing as well as for many heat sensitive compounds.
Discrete dislocation sim ulation of thin film plasticit y
Authors: von Blanckenhagen B. , Gumbsch P. , Arzt E. 
Published: April 2011

ABSTRACTA discrete dislocation dynamics sim ulation is used to investigate dislocation motion in the confined geometry of a polycrystalline thin film. The repeated activ ation of a Frank-Read source is sim ulated. The stress to activate the sources and to initiate plastic fiow is significantly higher than predicted by models where the dislocations extend o ver the entire film thic kness. An efiective source size, which scales with the grain dimensions, yields fiow stresses in reasonable agreemen t with experimen ts. The infiuence of dislocations deposited at interfaces is investigated by comparing calculations for a film sandwic hed between a substrate and a capping layer with those for a free standing film.
Solid Solution Alloy Effects on Microstructure and Indentation Hardness in Pt-Ru Thin Films
Authors: Hyun Seungmin , Kraft Oliver , Vinci Richard P. 
Published: April 2011

ABSTRACTThe elastic moduli and flow stresses of as-deposited Pt and Pt-Ru solid solution thin films were investigated by the nanoindentation method. The influence of solid solution alloying was explored by depositing Pt-Ru solid solution thin films with various compositions onto Si substrates. The 200 nm films were prepared by DC magnetron cosputtering with a Ru composition range from 0 to 20wt%. As expected, the modulus and the flow stress both increased significantly with an increase in Ru. The experimental results compare favorably to predictions based on a simple dislocation motion model consisting of three strengthening terms: substrate constraint, grain size strengthening and solid solution strengthening.
Temperature and Strain Rate Dependence of Deformation-Induced Point Defect Cluster Formation in Metal Thin Foils
Authors: Yasunaga K. , Matsukawa Y. , Komatsu M. , Kiritani M. 
Published: April 2011

ABSTRACTThe mechanism of plastic deformation in thin metal foils without involving dislocations was examined by investigating the variations in vacancy cluster formation during deformation for a range of deformation speeds and temperatures. The deformation morphology was not seen to change appreciably over a very wide range of strain rate, 10-4/s – 106/s, whereas the number density of vacancy clusters was observed to increase with increasing strain rate up to saturation value that is dependent on materials and temperature. The density of vacancy clusters decreased to zero with decreasing deformation speed. The strain rate at which the density of vacancy clusters begins to decrease was found to be proportional to the vacancy mobility, suggesting that the vacancies are generated as dispersed vacancies and escape to the specimen surfaces during slow deformation without forming clusters. A very long tail in the distribution of the density of vacancy clusters towards lower strain rates was reasonably attributed to the generation of small vacancy complexes due to deformation. These results give valuable information that can be used to establish new models for plastic deformation of crystalline metals without involving dislocations.
Misfit Dislocation Introduction During The Epitaxial Growth of Inas Islands on Gap
Authors: Gopal Vidyut , Vasiliev Alexander L. , Kvam Eric P. 
Published: April 2011

ABSTRACTThe initial growth of InAs on 11% lattice mismatched GaP substrates by molecular beam epitaxy was investigated. High resolution transmission electron microscopy (HREM) images showed that the InAs grew in the form of three-dimensional islands of dissimilar sizes. Mismatch induced strain relief was effected by the direct introduction of (mostly) edge dislocations at the corners of the islands. An examination of HREM images of several islands revealed that the island aspect ratio decreased with the introduction of misfit dislocations. Strain relaxation in the smaller, relatively dislocation-free islands occurred by elastic deformation of InAs lattice planes, which was more effective far from the constrained island-substrate interface. As a result, these islands grew taller and narrower, with a gradient in the elastic strain energy. However, a higher aspect ratio resulted in a higher surface area – to – volume ratio, and increased the surface energy of the InAs islands. Consequently, there was a driving force for the reduction of the aspect ratio if an alternate avenue for strain relaxation existed. The alternate route was plastic deformation by the introduction of misfit dislocations. As the island grew, the strain at the island corners increased, and beyond a critical value, misfit dislocations were added. These dislocations relieved strain at the heterointerface, and promoted the islands to grow laterally, i.e., the aspect ratio decreased. Islands coalesced, and a continuous layer resulted by a nominal thickness of 3 nm. Thus, the morphology of InAs islands grown on GaP was determined by the balance between elastic and plastic deformation.
Wafer Bonding of Silicon Carbide and Gallium Nitride
Authors: Lee Jaeseob , Cook T. E. , Bryan E. N. , Hartman J. D. , Davis R. F. , Nemanich R. J. 
Published: April 2011

ABSTRACTWafer bonding of SiC and GaN may prove important in the formation of high power heterojunction devices. Results of bonding SiC (C or Si surface) onto GaN (Ga surface) are presented. The samples were n-type 6H SiC and epitaxial n-type 2H(wurzite) GaN grown on SiC. The results demonstrate bonding for both possibilities, but the bonding of the C surface SiC to Ga surface GaN is more readily accomplished. A lower resistance was found for the C-face SiC/Ga-face GaN. The results indicate that the polarity of the interface is important for bonding of these materials.
Orientation and Boron Concentration Dependence of Si Layer Transfer by Mechanical Exfoliation
Authors: Henttinen Kimmo , Suni Tommi , Nurmela Arto , Airaksinen Veli-Matti , Suni Ilkka , Lau S.S 
Published: April 2011

ABSTRACTMechanical exfoliation strength has been measured in hydrogen implanted <100>, <111> and <110> oriented Si wafers using the crack opening method. The bonding temperature required for exfoliation increases in the order <100>, <111> and <110>. The same method has been applied to study the influence of boron doping on mechanical exfoliation in <100> Si wafers. The required bonding temperature to exfoliate mechanically decreases with increasing doping level independent of the electrical activation of boron. The enhanced crystallization rate of boron doped Si is suggested as a plausible explanation for the result.
Excimer Laser Annealing Effect on MILC Polycrystalline Silicon Film
Authors: Park Kee-Chan , Song In-Hyuk , Jung Sang-Hoon , Han Min-Koo 
Published: April 2011

AbstractXeCl excimer laser was irradiated on metal induced laterally crystallized (MILC) polycrystalline silicon (poly-Si) film in order to eliminate the intra-grain defects of MILC poly-Si film which incorporated 2 μm wide metal induced crystallized (MIC) poly-Si line pattern. On the irradiation of the laser beams, different melt and recrystallization phenomena were observed in the MILC and the MIC poly-Si region due to the Ni content difference in each film. The transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) measurements indicated that the melting temperature of the poly-Si film decreased as the Ni content increased. With the laser irradiation energy density of 370 mJ/cm2, 2 μm long defect-free poly-Si grain was successfully grown in the MILC poly-Si due to the melting temperature variation at the MILC-MIC poly-Si boundary.
PECVD Amorphous Silicon Nitride at 120°C for a-Si:H TFTs.
Authors: Stryahilev Denis , Sazonov Andrei , Nathan Arokia 
Published: April 2011

AbstractThe effect of a-SiNx films stoichiometry and their physical properties on the electrical integrity and masking ability is studied. The films are deposited at 120° C by 13.56 MHz PECVD from SiH4+NH3 + N2 gas mixture. They have the N/Si ratio of 1.4 to 1.7 and hydrogen concentration of 25 to 40 at.%. The electrical characterization was carried out by I-V measurements. An electrical resistivity of ∼1016 Ohm-cm and breakdown voltage of 5.5 MV/cm have been achieved for our PECVD nitride films. The performance of a-Si:H TFTs with these silicon nitride as the gate dielectric and passivation layer has been also evaluated.
Emission Properties of Nanostructured Carbon Field-Emission Cathodes
Authors: Chakhovskoi A.G , Chubun N.N , Hunt C.E. , Obraztsov A.N , Volkov A.P. 
Published: April 2011

AbstractPlanar field-emission cathode structures consisting of nanostructured carbon flakes have been investigated as an electron source for flat panel display application.Layers of nanoflakes were grown on silicon and molybdenum substrates using a high- temperature pyrolitic plasma-assisted CVD method. The result is a vertically oriented nanocluster layer of 1-2 micrometer height chemically bonded with the substrates. Additional orientation of the flakes, occurring during the first activation of the cathodes, was observed.Field emission properties of the emitters were studied in a vacuum chamber and in sealed flat-panel prototype devices with non-patterned low-voltage phosphor screens. Emitters with an area up to 1 square inch were tested under DC currents up to 100 microamps in diode mode. Anode bias up to 1.5 kV was applied. Current fluctuations of 1-2% were achieved using loading resistor.
Effects of Process Conditions on the Performance of Large Grain Poly-Silicon on Insulator (LPSOI) MOSFET for Advanced CMOS Applications
Authors: Shivani S. , Ng K. L. , Cheng C. F. , Poon M. C. , Chan Mansun 
Published: April 2011

AbstractEffects of process annealing temperature on Metal-Induced-Lateral-Crystallization (MILC) growth rate and quality of MILC polysilicon formed were studied. Raman spectrum analysis was employed for material characterization. MILC polysilicon layer, which was formed by applying an optimum annealing condition together with post high temperature annealing, could be used to fabricate Thin-Film-Transistor (TFT) with considerably electrical improvements. This reflected that good quality of the polysilicon layer. It is believed that the proposed MILC formation method can be empolyed to produce large grain polysilicon on insulator (LPSOI) for advanced devices and circuits' fabrication.
Positron Annihilation Lifetime Spectroscopy (Pals) Application in Metal Barrier Layer Integrity for Porous Low-K Materials
Authors: Lin Simon , Sun Jia-Ning , Gidley David W. , Wetzel Jeffrey T. , Monnig K.A. , Ryan E. Todd , Jang Simon , Yu Douglas , Liang M.S. 
Published: April 2011

AbstractPositron Annihilation Lifetime Spectroscopy (PALS) (1, 2) is a useful tool to pre-screen metal barrier integrity for Si-based porous low-k dielectrics. Pore size of low-k, thickness of metal barrier Ta, positronium (Ps) leakage from PALS, trench sidewall morphology, electrical test from one level metal (1LM) pattern wafer and Cu diffusion analysis were all correlated. Macro-porous low-k (pore size >= 200A) and large scale meso-porous low-k (>50∼200A) encounter both Ps leakage and Cu diffusion into low-k dielectric in the 0.25μmL/0.3μmS structures when using SEMATECH in-house PVD Ta 250A as barrier layer. For small scale meso-porous (>20∼50A) and micro-porous (<=20A) low-k, no Ps leakage and no Cu diffusion into low-k were observed even with PVD Ta 50A, which is proved also owing to sidewall densification to seal all sidewall pores due to plasma etch and ash. For future technology, smaller pore size of porous Si-based low-k (=< 50A) will be preferential for dense low-k like trench sidewall to avoid metal barrier integrity due to coverage problems from sidewall pores.
Plasticity Length Scale in LIGA Nickel MEMS Structures
Authors: Lou J. , Shrotriya P. , Allameh S. , Yao N. , Buchheit T. , Soboyejo W.O. 
Published: April 2011

AbstractThe plasticity length scale parameters associated with rotational and stretch gradients in LIGA nickel MEMS structures plated from sulfamate bath are presented in this paper. These are obtained from micro-bend and micro-tensile experiments on LIGA nickel films with different thicknesses. The composite length-scale parameter, lc is measured to be ∼ 4.8 νm for as-plated films (25, 50, 100 and 175 νm thick). The implications of the results are then discussed for the modeling of plasticity in LIGA nickel structures.
New MEMS Technology Using Multi-Layer NILC Poly-Si and NiSi Films
Authors: Cheung W. M. , Cheng C. F. , Poon M. C. , Qin M. , Yuen C. Y. , Chan Mansun 
Published: April 2011

AbstractA novel MEMS technology using multi-layer poly-silicon (poly-Si) is proposed. The poly-Si film is formed from the new Nickel-Induced-Lateral-Crystallization (NILC) method and has very large grain (>10νm) and near crystal quality. 700 nm thermal oxide was grown on a Si wafer. 100 nm LPCVD amorphous Si was deposited and followed by a 50 Å Ni deposition. The a-Si was crystallized at 550°C for 65 hours and subsequent 800°C for 2 hours to form the first (lower) NILC poly-Si layer. N-channel TFTs were fabricated on the NILC polysilicon layer. The process was repeated and a second (upper) polysilicon layer and TFTs were formed on top of the first polysilicon layer.The lower polysilicon has slightly larger grains and better material quality. Thin-film- transistors (TFT) fabricated on the 3-dimensional (3-D) poly-Si layers have I-V characteristics similar to (>40%) silicon-on-insulator TFTs. While TFTs on lower layer have better mobility and device properties, TFTs on upper layer have better uniformity. The accumulated heating and other effects have also been studied.
Aluminum-Silicon and Gold-Silicon Eutectics: New Opportunities for MEMS Technologies
Authors: Iliescu Ciprian , Poenar Daniel P. , Nanyang Jianmin Miao 
Published: April 2011

AbstractOur practical experiments highlight that aluminum-silicon (Al-Si) and gold-silicon (Au- Si) eutectics are fairly inert to the attack of both anisotropic and isotropic wet etchants of Si (e.g. KOH or HF/HNO3 solutions). Therefore, these interfacial eutectics can be used as etch-stop layers in wet etching-based bulk micromachining. This paper presents how Al-Si and Au-Si eutectic layers may be employed for applications whose production involves such operations (e.g. high-pressure sensors) and will discuss three major directions of interest: eutectic formation, diaphragm generation and application of the eutectic layer in a pressure sensor.
Materials Issues in the Application of Silicon Nitride Films in Silicon MEMS
Authors: Moore David F. , Bostock Roger M. , Boyle Paul , Conradie Ewan H. 
Published: April 2011

AbstractThis paper reviews bulk micromachining of Si, with particular reference to the microassembly and packaging of optical and electronic components. Taking as an example the use of 2.3 [.proportional]m thick silicon nitride microclips to hold an optic fibre in place in a silicon V-groove, the potential of thin film packaging is briefly assessed. The fabrication process is to: [i] deposit a controlled stress silicon nitride layer onto a blank (100) oriented silicon wafer by chemical vapour deposition (standard LPCVD but silicon rich); [ii] pattern the silicon nitride clip mask shape by optical lithography and reactive ion etching; and [iii] remove the underlying silicon to form a V-shaped groove with an anisotropic liquid etch process using the silicon nitride as a mask. From the measured deflection of a silicon nitride beam when a force is applied, the Young's modulus is 400 GPa. The beams are rugged and a clipping force of 10 N per metre of optic fibre length is achieved.This approach to applying the mechanical properties of thin films is compatible with standard thin film technology, enables precise microassembly, and has great potential to reduce manufacturing costs in a wide range of sensors and microsystems. In some applications high temperature processing must be avoided, even early on in the manufacturing process. Using low temperature processing, robust clips from silicon nitride made by plasma enhanced chemical vapour deposition (PECVD and hydrogen rich) are made, but the Young's modulus of this material is typically 40 GPa and the clipping force is correspondingly small. The paper concludes by assessing the prospects for other thin film materials in mechanical MEMS and packaging.
Thin Film Superconducting MgB2 Grown by MBE without Post-Anneal
Authors: Jo William , Huh Jeong-Uk , Ohnishi Tsuyoshi , Marshall Ann F. , Beasley Malcolm R. , Hammond Robert H. 
Published: April 2011

ABSTRACTWe report the synthesis of superconducting MgB2 thin films grown in-situ by molecular beam epitaxy (MBE). Mg-rich fluxes are deposited with B-flux by electron beam evaporation onto c- and r-plane sapphire substrates. Deposition temperature is varied between 260 ∼ 320 °C. Base pressure of the MBE chamber is at low 10-10 Torr, rising to 10-8 Torr during deposition due mostly to the presence of hydrogen and nitrogen. Asgrown MgB2 films show superconducting transition at ∼ 34 K with ΔTc < 1 K. The films on c-plane sapphire substrates exhibit c-axis oriented peaks of MgB2, and full-width at half maximum of 3 degree in their rocking curves. Azimuthal phi-scan of the MgB2(101) peak shows 12-fold symmetric peaks, which is confirmed by selected area diffraction pattern in transmission electron microscopy (TEM). Plan-view TEM shows hexagonal-shaped grain growth with grain size of about 400 Å.