bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toward understanding the degradation without light soaking in hot-wire a-Si:H thin films and solar cells
Authors: Wang Qi , Wang Keda , Han Daxing 
Published: June 2019

AbstractThe non-reversible degradation without light soaking has been observed in both thin films and solar cells fabricated using the hot-wire CVD technique. For solar cells, a 9.8% initial efficiency became 9.2% when measured after a few weeks of being stored in the dark. For the intrinsic layers, the conductivity increased in the air but remained steady in vacuum up to 700 hours. Also, the conductivity increased and activation energy decreases from an initial ∼0.95 eV to ~∼0.85 eV after several thermal cycles, even in a vacuum. We suggest that the degradation in both materials and solar cells come from the same origin: the upward shift of the Fermi-energy position from its initial value. In other words, the as-grown material is slightly p-type and gradually became slightly n-type after sitting in the air or after thermal annealing cycles in a vacuum. The shift in the Fermi-energy made the fill factor of the solar cell decrease and changes in the electronic properties of the i-layer. It is likely that adsorption of oxygen from water vapor is driving this degradation.
Nanocrystalline silicon ( nc-Si ) from single ion beam sputtering
Authors: Zhou Z.B. , Hadi G.M. , Cui R.Q. , Ding Z.M. , Li G. 
Published: June 2019

AbstractBased on a small set of selected publications on the using of nanocrystalline silicon films (nc-Si) for solar cell from 1997 to 2001, this paper reviews the application of nc-Si films as intrinsic layers in p-i-n solar cells. The new structure of nc-Si films deposited at high chamber pressure and high hydrogen dilution have characters of nanocrystalline grains with dimension about several tens of nanometer embedded in matrix of amorphous tissue and a high volume fraction of crystallinity (60~80%). The new nc-Si material have optical gap of 1.89 eV. The efficiency of this single junction solar cell reaches 8.7%. This nc-Si layer can be used not only as an intrinsic layer and as a p-type layer. Also nanocrystalline layer may be used as a seed layer for the growth of polycrystalline Si films at a low temperature.We used single ion beam sputtering methods to synthesize nanocrystalline silicon films successfully. The films were characterized with the technique of X-ray diffraction, Atomic Force Micrographs. We found that the films had a character of nc-amorphous double phase structure. Conductivity test at different temperatures presented the transportation of electrons dominated by different mechanism within different temperature ranges. Photoconductivity gains of the material were obtained in our recent investigation.
Investigation of the Causes and Variation of Leakage Currents in Amorphous Silicon P-I-N Diodes
Authors: Johnson Todd R. , Ganguly Gautam , Wood George S. , Carlson David E. 
Published: June 2019

AbstractExcess leakage currents under reverse bias (known as shunting) and spontaneous reductions of this excess leakage under increased reverse bias (known as curing) were investigated in hydrogenated amorphous silicon (a-Si:H) based single junction p-i-n type diodes. An increase in the frequency of shunting was observed when the front contacts were switched from tin oxide to zinc oxide, most likely due to defects in the previously deposited zinc oxide coated glass was observed. Storage in the dark and light soaking up to 100 hours were both observed to independently increase the leakage current in previously leaking diodes. Models for the distribution of shunt-causing defects within a given cell area were considered. Comparing the measured frequency of shunting using cells of varying area (1 to 16 mm2) to the models' predictions indicate a distribution of point defects separated by relatively large average distances that are slightly larger for tin oxide (5-6 mm) than for zinc oxide (4 mm).
Room Temperature Recovery of Light Induced Changes in Amorphous Silicon Solar Cells
Authors: Ganguly G. , Carlson D.E. , Bennett M.S. , Willing F. , Arya R.R. , Stradins P. 
Published: June 2019

AbstractWe have observed the recovery of the performance of amorphous silicon (a-Si:H) based solar cell (especially the fill factor) at temperatures between 25°C and 170°C after ∼600 hours of light soaking under 1 sun illumination at ∼40°C. We find that there is some recovery of the fill factor of the cells even at temperatures below the temperature of light soaking. The recovery is significantly greater in cells of poor quality. There is also some evidence of enhancement of the recovery rate due to an external electric field. Above the light soaking temperature, a sort of thermally activated recovery of the fill factor is observed.
Calculations of SiH3 Diffusion and Growth Processes on a-Si:H Surfaces
Authors: Vigneron P , Peacock P W , Xiong K , Robertson J 
Published: June 2019

AbstractSurface diffusion of a growth species is needed to give the observed smooth surface of hydrogenated amorphous silicon (a-Si:H). But what diffuses, the weakly bound SiH3 radical on the hydrogenated surface, or the bound SiH3 at a growth site. Diffusion is complicated by the change in the surface termination of a-Si:H as temperature rises. We use total energy pseudopotential calculations on a variety of periodic Si:H surface configurations to show that it is the weakly bound SiH3 that diffuses. We provide an overall energy scheme of the bound states and transport levels of SiH3 on a-Si:H surfaces.
Experimental Characterization of the Reliability of Multi-Terminal Dual-Damascene Copper Interconnect Trees
Authors: Gan C. L. , Thompson C.V. , Pey K. L. , Choi W. K. , Chang C. W. , Guo Q. 
Published: June 2019

AbstractThe reliability of Cu dual-damascene interconnect trees with 3-terminal (dotted-I), 4-terminal (‘T’) and 5-terminal (‘+’) configurations has been investigated. The lifetime of multiterminal interconnect trees with the same current density through the common middle via was determined to be independent of the number of segments connected at the common junction. Furthermore, our experimental results on dotted-I test structures showed an increase in the reliability of the interconnect tree when the distribution of a same current was not equal in the two connected segments, especially for the cases where one of the segments was acting as a passive reservoir or active source of Cu atoms for the adjoining segment. Due to the low barrier for void nucleation at the Cu/Si3N4 interface, the presence of any small atomic source in neighboring segments will enhance the reliability of a connected segment in which Cu atoms are being drained away. As a consequence, failure can occur in a tree segment which is stressed at significantly lower current densities than more highly stressed adjoining segments.
Effect of barrier layers on the texture and microstructure of Copper films
Authors: Muppidi Tejodher , Field David P 
Published: June 2019

AbstractThe microstructure of interconnect material is know to influence its electromigration and stress-voiding properties. In addition to many factors responsible for the microstructure development, the barrier layer could be a major contributing factor as it forms the substrate for the copper films above. The microstructure of the barrier films based on its deposition technique could determine the final microstructure of the copper film. In the present work we examine the effect of two different barrier layers (Ta and TaN) and different stackings of these two materials on the microstructure on the copper seed (PVD) and electroplated films using EBSD, AFM and XRD. The results show that the plated films have a predominantly (111) texture and uniform grain size. But the (111) texture maximum varied with the barrier layer stacking underneath the plated film.
Electromigration of lower and upper Cu lines in dual-damascene Cu interconnects
Authors: Krishnamoorthy Ahila , Qiang Guo , Vairagar Anand V. , Mhaisalkar Subodh 
Published: June 2019

AbstractElectromigration in upper M2 and lower M1 Cu lines in dual damascene interconnects was investigated by using two types of via terminated structures. Two different types of failures termed as abrupt and gradual failures were observed. Electromigration failures in M2 were mostly by gradual failures, while abrupt failures dominated in M1. Significantly different types of voids were observed in M1 as compared to those in M2, though similar resistance change was observed. Experimentally calculated activation energies for M1 and M2 indicated interfacial electromigration. Activation energy of M1 was found to be much lower than that of M2. This clearly demonstrates the asymmetry of electromigration in M2 and M1 Cu lines in dual damascene interconnects.
The formation of low temperature Cu3Si in Ag(Cu)/Si structure upon annealing and its effects on adhesion and resistivity
Authors: Hong Sungjin , Lee Seob , Ko Yeonkyu , Lee Jaegab 
Published: June 2019

AbstractThe annealing of Ag(40 at.% Cu) alloy films deposited on a Si substrate at 200 – 800 oC in vacuum has been conducted to investigate the formation of Cu3Si at the Ag-Si interface and its effects on adhesion and resistivity of Ag(Cu)/Si structure. Auger electron spectroscopy(AES) analysis showed that annealing at 200°C allowed a diffusion of Cu to the Si surface, leading to the significant reduction in Cu concentration in Ag(Cu) film and thus causing a rapid drop in resistivity. In addition, the segregated Cu to the Si surface reacts with Si, forming a continuous copper silicide at the Ag(Cu)/Si interface, which can contribute to an enhanced adhesion of Ag(Cu)/Si annealed at 200 oC. However, as the temperature increases above 300°C, the adhesion tends to decrease, which may be attributed to the agglomeration of copper silicide beginning at around 300°C.
Material and Electrical Characterization of HfO2 Films for MIM Capacitors Application
Authors: Hu Hang , Zhu Chunxiang , Lu Y. F. , Wu Y. H. , Liew T. , Li M. F. , Cho B.J. , Choi W. K. , Yakovlev N. 
Published: June 2019

AbstractThin films of HfO2 high-κ dielectric have been prepared by pulsed-laser deposition (PLD) at various deposition conditions. X-ray diffraction (XRD), atomic force microscopy (AFM), and secondary ion mass spectroscopy (SIMS) were used to characterize the deposited films. Experimental results show that substrate temperature has little effect on the stoichiometry, while deposition pressure plays an important role in determining the ratio of Hf and O. The electrical properties of HfO2 Metal-Insulator-Metal (MIM) capacitors were investigated at various deposition temperatures. It is shown that the HfO2 (56 nm) MIM capacitor fabricated at 200 oC shows an overall high performance, such as a high capacitance density of ∼3.0 fF/νm2, a low leakage current of 2x10-9 A/cm2 at 3 V, etc. All these indicate that the HfO2 MIM capacitors are very suitable for use in Si analog circuit applications.
Air Bridge Technology: A Comparison of Novel Interconnect Materials and Integration Schemes for Beyond 45 nm
Authors: Foster Kenneth , Waeterloos Joost , Frye Don , Froelicher Steve , Mills Mike 
Published: June 2019

AbstractThe electronics industry, in a continual drive for improved integrated device performance, is seeking increasingly lower dielectric constants (k) of the insulators that are used as interlayer dielectric (ILD) for advanced logic interconnects. As the industry continually seeks a stepwise reduction of the “effective” dielectric constant (keff), simple extendibility, leads to the consideration of the highest performance possible, namely air bridge technology. In this paper we will discuss requirements, integration schemes and properties for a novel class of materials that has been developed as part of an advanced technology probe into air bridge architecture. We will compare and contrast these potential technology offerings with other existing dense and porous ILD integration options, and show that the choice is neither trivial nor obvious.
3D System Integration Technologies
Authors: Ramm Peter , Klumpp Armin , Merkel Reinhard , Weber Josef , Wieland Robert , Ostmann Andreas , Wolf Jürgen 
Published: June 2019

AbstractIn the last years strong efforts were made to miniaturize microelectronic systems. Chip scale packages, flip chips and multichip modules are now commonly used in a great variety of products (e. g. mobile phones, hand-held computers and chip cards). Future microelectronic applications require significantly more complex devices with increased functionality and performance. Due to added device content, chip area will also increase. Performance, multi-functionality and reliability of microelectronic systems will be limited mainly by the wiring between the subsystems (so called “wiring crisis”), causing a critical performance bottleneck for future IC generations. 3D System Integration provides a base to overcome these drawbacks. Furthermore, systems with minimum volume and weight as well as reduced power consumption can be realized for portable applications. 3D integrated systems show reduced chip areas and enable optimized partitioning, both which decrease the fabrication cost of the system. An additional benefit is the enabling of minimal interconnection lengths and the elimination of speed-limiting inter-chip interconnects. 3D concepts which take advantage of wafer level processing to avoid increasing package sizes and expensive single component assembling processes have the potential to integrate passive devices resistors, inductors and capacitors into the manufacturing system and provide full advantage for system performance.The ITRS roadmap predicts an increasing demand for systems-on-a-chip (SoC) [1]. Conventional fabrication is based on embedded technologies which are cost intensive. A new low cost fabrication approach for vertical system integration is introduced. The wafer-level 3D SoC technology, optimized to the capability for chip-to-wafer stacking has the potential to replace embedded technologies based on monolithic integration.
Expanding thermal plasma for low-k dielectrics deposition
Authors: Creatore M. , Barrell Y. , Kessels W.M.M. , Sanden M.C.M. van de 
Published: June 2019

AbstractAs the need for low-k dielectrics in the ULSI technology becomes urgent, the research primarily focuses on the deposition of novel materials with appropriate electrical properties and on the challenges concerning their integration with subsequent processing steps. In this framework we introduce the expanding thermal plasma as a novel remote technique for the deposition of low-k carbon-doped silicon dioxide films from argon/hexamethyldisiloxane/oxygen mixtures. We have obtained k values in the range 2.9-3.4 for films characterized by acceptable mechanical properties (hardness of 1 GPa).
Organofluorosilicate Glass (OFSG): A Dense Low K Dielectric with Superior Materials Properties
Authors: O'Neill M.L. , Cheng Y.L. , Lukas A.S. , Wang Y.L. , Karwacki E.J. , Feng M.S. , Vrtis R.N. , Vincent J.L. , Peterson B.K. , Bitner M.D. 
Published: June 2019

AbstractOrganofluorosilicate glass (OFSG) films with the composition Si:O:C:H:F were deposited via plasma-enhanced CVD from mixtures of trimethylsilane (3MS), silicon tetrafluoride (SiF4), and oxygen (O2). OFSG films have significantly enhanced mechanical strength, thermo-oxidative stability, and adhesion compared with OSG films deposited from 3MS and O2 alone. We propose that the increased density of OFSG, which helps improve mechanical strength, is balanced by the presence on non-polarizable Si-F functionalities, which serve to lower the dielectric constant.
Single walled 0.4 nm carbon nanotube bundles prepared by pyrolysis of n-hexane catalyzed by ferrocene
Authors: Wang Qixiang , Ning Guoqing , Wei Fei , Luoa Guohua 
Published: June 2019

AbstractBundles of single walled 0.4 nm carbon nanotubes were prepared by chemical vapor deposition using n-hexane as carbon source catalyzed by ferrocene with additives of thiophene at 1373 K. 8 cm long rope of single walled carbon nanotubes with diameters of 0.8-1.18 nm was also synthesized. The products were characterized by scanning electron microscopy, high resolution transmission electron microscopy and Raman spectroscopy.
Integration of Carbon Nanotubes Devices Into Microelectronics
Authors: Hoenlein W. , Kreupl F. , Duesberg G.S. , Graham A.P. , Liebau M. , Seidel R. , Unger E. 
Published: June 2019

AbstractCarbon Nanotubes (CNTs) offer extraordinary properties for applications in microelectronics. We assess the methods used to grow CNTs for integration into microelectronics, in particular, metallic carbon nanotubes for vias and interconnects as well as semiconducting CNTs for fieldeffect devices are discussed. State-of-the-art CNTFETs are compared to Si-MOSFETs. A vertical CNTFET (VCNTFET) device concept is presented which offers better growth control, adding a new quality to microelectronics and making real 3-dimensional electronics possible.
The Magnetochiral Effect in Charge Transport in Carbon Nanotubes
Authors: Krstic Vojislav , Roth Siegmar , Burghard Marko , Kern Klaus , Rikken Geert L.J.A. 
Published: June 2019

AbstractNanotubes forming carbon atoms arrange differently, resulting into three main types of carbon nanotubes: armchair, zigzag, chiral. Thus, depending on their type, nanotubes may be regarded as chiral, molecular electrical conductors. As a consequence of symmetry arguments, the magnetoresistance of such tubes depends on the relative orientation of the traversing current and the external magnetic field. Magnetotransport measurements on single walled carbon nanotubes have been performed showing the expected dependence on both the current and magnetic field. Further, the quantum-mechanical model of a free electron on a helix in an external magnetic field is discussed in order to provide indicators to possible microscopic mechanisms.
Synthesis, Analysis, Transport and Field emission Measurements of Compound B-C-N Nanotubes
Authors: Golberg Dmitri , Bando Yoshio , Dorozhkin Pavel , Dong Zhen-Chao , Tang Cheng-Chun , Kurashima Keiji , Mitome Masanori 
Published: June 2019

AbstractMultiwalled B-C-N nanotubes of various morphologies and chemical compositions were synthesized by reacting C-based nanotube templates with boron oxide and nitrogen at 1573 K- 2173 K. The nanotubes were thoroughly analysed using a high-resolution field-emission 300 kV transmission electron microscope (TEM), an energy-filtered field-emission 300 kV electron microscope (Omega filter), an electron energy loss spectrometer and an energy dispersion X-ray detector. Transport and field emission properties of the nanotubes were studied using a low energy electron point source microscope and via in-situ measurements in TEM equipped with a scanning tunnelling microscope (STM) unit.
Carbon-Nanotube Engineering for Probes and Tweezers Operating in Scanning Probe Microscope
Authors: Nakayama Yoshikazu , Akita Seiji 
Published: June 2019

AbstractWe have developed a series of processes for preparing carbon nanotube devices of probes and tweezers that operate in scanning probe microscope (SPM). The main developments are a nanotube cartridge where nanotubes are aligned at a knife-edge to be easily picked up one by one and a scanning-electron-microscope manipulator by which a nanotube is transferred from the nanotube cartridge onto a Si tip under observing its view.We have also developed the electron ablation of a nanotube to adjust its length and the sharpening of a multiwall nanotube to have its inner layer with or without an end cap at the tip. For the sharpening process, the free end of a nanotube protruded from the cartridge was attached onto a metal-coated Si tip and the voltage was applied to the nanotube. At a high voltage giving the saturation of current, the current decreased stepwise in the temporal variation, indicating the sequential destruction of individual nanotube layers. The nanotube was finally cut at the middle of the nanotube bridge, and its tip was sharpened to have an inner layer with an opened end. Moving up the cartridge before cutting enables us to extract the inner layer with an end cap.It is evidenced that the maximum current at each layer during the stepwise decrease depends on its circumference, and the force for extracting the inner layer with ∼ 5nm diameter is ∼ 4 nN.
Localized Fabrication of Mental Contacts and Electrical Measurements on Multi walled Carbon Nanotubes
Authors: Ziroff J. , Agnello G. , Rullan J. , Dovidenko K. 
Published: June 2019

AbstractA Focused Ion Beam (FIB) microscope was to locally deposit platinum contacts on Multiwalled Carbon Nanotubes (MWNTs) for resistance and current carrying capability measurements. We have determined the resistivity of these ultra-thin Pt lines and the MWNT-Pt contact resistance to account for contributions to the MWNT measurements. We have studied the effects of secondary mental deposition around the contacts (‘halo’ effect) on the MENT electrical measurements as well as effects of ion beam exposure and possible ways to avoid/minimize them. Transmission Electron Microscopy data was used to evalutate MWNT surface modifications due to ion beam exposure and Pt deposition.
Deformation of Small Volumes of Material Studied Using Strained-Layer Superlattice Structures
Authors: P'ng K.M.Y. , Bushby A.J. , Dunstan D.J. 
Published: June 2019

AbstractMechanical studies of semiconductor superlattices have shown that the onset of plastic deformation under an inhomogeneous stress is a process that takes place simultaneously across a finite volume of the order of a micron across. The ability to incorporate known internal stresses, and to vary the stress and thickness of individual layers in a semiconductor superlattice, is a very powerful tool, opening up new possibilities for investigations that cannot be achieved by varying external stresses on a specimen that is sensibly homogeneous. In this way, from the initial yield stress of single-crystal strained-layer superlattices under indentation, we demonstrated a new criterion, of which the key feature is that it is to be averaged over a finite volume. Here we show that designing samples with individual layers in bands to form low yield-stress material within the structure can give information about the size and position of the initial yield volume.
Atomistic and Continuum Studies of Diffusional Creep and Associated Dislocation Mechanisms in thin Films on Substrates
Authors: Buehler Markus J. , Hartmaier Alexander , Gao Huajian 
Published: June 2019

AbstractMotivated by recent theoretical and experimental progress, large-scale atomistic simulations are performed to study plastic deformation in sub-micron thin films. The studies reveal that stresses are relaxed by material transport from the surface into the grain boundary. This leads to the formation of a novel defect identified as diffusion wedge. Eventually, a crack-like stress field develops because the tractions along the grain boundary relax, but the adhesion of the film to the substrate prohibits strain relaxation close to the interface. This causes nucleation of unexpected parallel glide dislocations at the grain boundary-substrate interface, for which no driving force exists in the overall biaxial stress field. The observation of parallel glide dislocations in molecular dynamics studies closes the theory-experiment-simulation linkage. In this study, we also compare the nucleation of dislocations from a diffusion wedge with nucleation from a crack. Further, we present preliminary results of modeling constrained diffusional creep using discrete dislocation dynamics simulations.