bluuebunny/crossref_metadata_2025_split huggingface dataset:
CO2 laser annealing synthesis of silicon nanocrystals buried in Si-rich SiO2
Authors: Lin Chun-Jung , Chueh Yu-Lun , Chou Li-Jen , Kuo Hao-Chung , Lin Gong-Ru 
Published: June 2019

AbstractLocalized synthesis of 3-8 nm Si nanocrystals (nc-Si) in PECVD-grown Si-rich SiO2 (SRSO) film is demonstrated using CO2 laser annealing at an intensity below the ablation-threshold (6.0 kW/cm2). At an optimized surface temperature of 1285°C, the precipitated nc-Si in CO2-laser-annealed SRSO film results in near-infrared photoluminescence (PL) at 806 nm, whereas the ablation damage induced at higher laser intensities as well as temperatures results in blue PL at 410 nm related to structural defects. The refractive index of the laser-annealed SRSO at 633 nm increases from 1.57 to 2.31 as the laser intensity increases from 1.5 to 6.0 kW/cm2. Transmission electron microscopy analysis reveals that the average size and volume density of Si nanocrystals embedded in the SRSO film are about 6 nm and 4.5×1016 cm-3, respectively. The CO2 laser annealing with controlled intensity and spot size can potentially accomplish in-situ, localized annealing of the SRSO film without causing irreversible damage to nearby electronics.
Crystallographic Study of The Initial Growth Region of μc-Si with Different Preferential Orientations
Authors: Sobajima Y. , Sugano T. , Kitagawa T. , Toyama T. , Okamoto H. 
Published: June 2019

AbstractGrowth of microcrystalline silicon (μc-Si) thin films with different preferential orientations has been studied employing XRD measurements versus thickness. The focus of this study is on the influence of preferential orientation on the film growth process. The (220) preferential orientation and randomly oriented μc-Si films studied here were prepared by VHF-PECVD at 180 °C. The thickness evolution revealed that the crystallinity was improved in the μc-Si with (220) preferential orientation μc-Si particularly in the first 0.5-μm of growth, while that in the randomly oriented μc-Si was almost completely unchanged. The difference in the crystallinity in the initial growth region arises from a difference in the growth mechanisms. Specifically, the growth of μc-Si with (220) preferential orientation can be elucidated by a hybrid-phase mode consisting of vapor- and solid-phase growth, whereas the growth of randomly oriented μc-Si can be achieved only by vapor-phase growth as occurs conventionally. Based on the growth mechanisms, the microstructures of μc-Si with both orientations and their influence on the photovoltaic performance are discussed.
Silicon homoepitaxy using tantalum-filament hot-wire chemical vapor deposition
Authors: Teplin Charles W. , Iwaniczko Eugene , Jones Kim M. , Reedy Robert , To Bobby , Branz Howard M. 
Published: June 2019

AbstractWe have studied silicon films grown epitaxially on silicon wafers using hot-wire chemical vapor deposition (HWCVD) with a tantalum filament. Silicon films were grown on (100)-oriented hydrogen terminated silicon wafers at temperatures from 175°C to 480°C, using a Ta filament 5 cm from the substrate to decompose pure SiH4 gas. The progression of epitaxy was monitored using real-time spectroscopic ellipsometry (RTSE). Analysis using RTSE, transmission electron microscopy (TEM), and scanning electron microscopy shows that at a characteristic thickness, hepi all of the films break down into a-Si:H cones. Below 380°C, both hepi and the thickness of the transition to pure a-Si:H increase with increasing temperature. Above 380°C, hepi was not observed to increase further but TEM images show fewer defects in the epitaxial regions. Secondary ion-mass spectrometry shows that the oxygen concentration remains nearly constant during growth (<1018 cm-3). The hydrogen concentration is found to increase substantially with film thickness from 5·1018 to 5·1019 cm-3, likely due to the incorporation of hydrogen into the a-Si:H cones that grow after the breakdown of epitaxy.
Temperature-Dependent Open-Circuit Voltage Measurements and Light-Soaking in Hydrogenated Amorphous Silcon Solar Cells
Authors: Liang Jianjun , Schiff E. A. , Guha S. , Yan B. , Yang J. 
Published: June 2019

AbstractWe present temperature-dependent measurements of the open-circuit voltage VOC(T) in hydrogenated amorphous silicon nip solar cells prepared at United Solar. At room-temperature and above, VOC measured using near-solar illumination intensity differs by as much as 0.04 V for the as-deposited and light-soaked states; the values of VOC for the two states converge below 250 K. Models for VOC based entirely on recombination through deep levels (dangling bonds) do not account for the convergence effect. The convergence is present in a model that assumes the recombination traffic in the as-deposited state involves only bandtails, but which splits the recombination traffic fairly evenly between bandtails and defects for the light-soaked state at room-temperature. Recombination mechanisms are important in understanding light-soaking, and the present results are inconsistent with at least one well-known model for defect generation.
Improved Back Reflector for High Efficiency Hydrogenated Amorphous and Nanocrystalline Silicon Based Solar Cells
Authors: Yan Baojie , Owens Jessica M. , Jiang Chun-Sheng , Yang Jeffrey , Guha Subhendu 
Published: June 2019

AbstractAg/ZnO back reflectors (BR) on specular stainless steel substrates are optimized for hydrogenated amorphous silicon germanium alloy (a-SiGe:H) and nanocrystalline silicon (nc-Si:H) solar cells. The BRs are deposited using a sputtering method. The texture of the Ag and ZnO layers is controlled by deposition parameters as well as chemical etching with diluted HCl. The surface morphology is investigated by atomic force microscopy. The scattered light intensity from a He-Ne laser, which illuminates the sample surface perpendicularly, is measured at different angles. Finally, a-SiGe:H and nc-Si:H solar cells are deposited on the BR substrates prepared under various conditions. For a-SiGe:H bottom cells, the improved BR with large micro-features leads to an enhanced open-circuit voltage. For the nc-Si:H solar cells, large micro-features on the improved BR eliminate interference fringes otherwise observed in the quantum efficiency measurement and result in high short circuit current density. The result is consistent with an enhanced scattered light intensity. Hence, the cell performance was improved. We also deposited a-Si:H/a-SiGe:H/nc-Si:H triple-junction cells on the optimized BR and achieved a high initial active-area efficiency of 14.6%.
Metastable Changes in the Photoconductive Properties of Microcrystalline Silicon Upon Heat Treatment
Authors: Brüggemann R. 
Published: June 2019

AbstractWe demonstrate that metastable changes or instabilities in the dark conductivity of microcrystalline silicon upon heat treatment and ambient conditions, which have been reported in the literature, are accompanied by changes in the photoconductivity or the majority-carrier mobility-lifetime product. The minority-carrier mobility-lifetime product and sub-gap absorption appear to be much less affected by different heat treatment procedures and ambient conditions. The observations can be related to Fermi-level induced change in defect occupancy by which the effective density of recombination centres is reduced for electrons but remains the same for holes. Minority carrier properties seem to be better suited as an indicator for sample quality and for comparison of microcrystalline silicon samples from different laboratories.
Light-Intensity Dependence of the Staebler-Wronski Effect in a-Si:H with Various Densities of Defects
Authors: Kumeda Minoru , Sakai Ryohei , Morimoto Akiharu , Shimizu Tatsuo 
Published: June 2019

AbstractThe light-intensity dependence of the photocreation of dangling bonds (DBs) were investigated for a-Si:H films with increasing density of defects before light soaking. Samples in which the density of neutral DBs had been increased by annealing at 400 C for 1 h exhibited a weak light-intensity dependence of the photocreated DBs compared to that for the as-deposited sample. Furthermore, the sample which had been illuminated with a light intensity of 1 W/cm2 for 1 h also showed a weak dependence. The results can be qualitatively explained by using rate equations for the densities of DBs and floating bonds (FBs) based on the FB-mediated photocreation of DBs. When both the densities of DBs and FBs before illumination increase, the light-intensity dependence of the DB density for a moderate value of the illumination time becomes weaker, qualitatively consistent with the observed results.
Charging effect of a nc-Si in a SiO2 layer observed by scanning probe microscopy
Authors: Son J. M. , Kim J. M. , Khang Y. , Lee E. H. , Park S. I. , Kim Y. S. , Kang C. J. 
Published: June 2019

AbstractScanning probe microscopy (SPM) with a conducting tip has been used to electrically probe silicon nanocrystals (NCs) on an insulating substrate. NC samples were produced by aerosol techniques followed by a sharpening oxidation. The size of NCs is in the range of 10-50nm and deposited on a silicon substrate with a density of around 1011/cm2. Using a conducting tip, the charge was injected directly into the NCs, and the bias dependent images due to the trapped charges in the NCs were monitored. Charging effects affected by the size of NCs and injection direction were also estimated from the apparent height differences of the NCs with respect to the applied bias.
Application of SC-Simul for Numerical Modeling of the Opto-Electronic Properties of Heterojunction Diodes
Authors: Brüggemann R. , Rösch M. , Tardon S. , Bauer G.H. 
Published: June 2019

AbstractWe apply the publicly available device modeling tool SC-Simul for simulating experiments with user-defined heterojunction diodes to discuss the role of the electric field in solar cells. For amorphous silicon/crystalline silicon heterodiodes, the role of interface defects, an amorphous silicon buffer layer and low-cost crystalline silicon is studied by simulation of current-voltage characteristics and photoluminescence. Photoluminescence is sensitive to the minority carrier density in the volume of the device and can be used to monitor minority carrier properties in these diodes.
A New Technique for the Characterization of the Adhesion in Integrated Circuit Interconnect Structures
Authors: Ocana Ibon , Molina Jon M. , Gonzalez Diego , Elizalde M. Reyes , Sanchez Jose M. , Martinez-Esnaola Jose M. , Gil-Sevillano Javier , Scherban Tracey , Pantuso Daniel , Sun Brad , Xu Guanghai , Miner Barbara , He Jun , Maiz Jose A. 
Published: June 2019

AbstractA new testing technique for the characterization of the mechanical behavior of the interconnect structures of integrated circuit devices is introduced in this paper. Modified crosssectional nanoindentation (MCSN) is the result of extending cross-sectional indentation (CSN) to patterned structures. As in conventional CSN, a Berkovich indenter is used to initiate fracture in the silicon substrate beneath the interconnect structure. The cracks propagate through this structure, preferentially along the weakest interfaces in the system. A FIB (Focused Ion Beam) is used for sample preparation, machining a trench parallel to the indentation surface. In this way, the crack growth can be better controlled and the problem may be modeled in two dimensions.The technique has been used to study crack propagation in patterned structures as a function of thin film composition and processing. The results obtained, in terms of crack length along each interface studied, correlate well with the fracture energy measured by four-point bending (4 PB) in blanket films of the same materials. Finite element modeling of the stress fields in the vicinity of the crack tip has been carried out to understand the crack paths observed.
Effects of Bonding Process Parameters on Wafer-to-Wafer Alignment Accuracy in Benzocyclobutene (BCB) Dielectric Wafer Bonding
Authors: Niklaus F. , Kumar R.J. , McMahon J.J. , Yu J. , Matthias T. , Wimplinger M. , Lindner P. , Lu J.Q. , Cale T.S. , Gutmann R.J. 
Published: June 2019

AbstractWafer-level three-dimensional (3D) integration is an emerging technology to increase the performance and functionality of integrated circuits (ICs). Aligned wafer-to-wafer bonding with dielectric polymer layers (e.g., benzocyclobutene (BCB)) is a promising approach for manufacturing of 3D ICs, with minimum bonding impact on the wafer-to-wafer alignment accuracy essential. In this paper we investigate the effects of thermal and mechanical bonding parameters on the achievable post-bonding wafer-to-wafer alignment accuracy for polymer wafer bonding with 200 mm diameter wafers. Our baseline wafer bonding process with softbaked BCB (∼35% cross-linked) has been modified to use partially cured (∼ 43% crosslinked) BCB. The partially cured BCB layer does not reflow during bonding, minimizing the impact of inhomogeneities in BCB reflow under compression and/or slight shear forces at the bonding interface. As a result, the non-uniformity of the BCB layer thickness after wafer bonding is less than 0.5% of the nominal layer thickness and the wafer shift relative to each other during the wafer bonding process is less than 1 μm (average) for 200 mm diameter wafers. The critical adhesion energy of a bonded wafer pair with the partially cured BCB wafer bonding process is similar to that with soft-baked BCB.
Pore Structure and Integration Performance of a Porous CVD Ultra Low k Dielectric
Authors: Liu Youfan , Knorr Andreas , Wu Wen-Li , Gidley David , Kastenmeier Bernd 
Published: June 2019

AbstractA porous ultra low k PECVD dielectric has been evaluated at SEMATECH for 45 nm and beyond technology node applications. Material structure, integration performance, and electrical characteristics were investigated in a one level metal single damascene integrated structure.
Effect of Dielectric Pore Size Distribution on Interfacial Adhesion of the Tantalum-Porous Dielectric Interface
Authors: Saxena R. , Cho W. , Rodriguez O. , Gill W. N. , Plawsky J. L. , Tsui T. , Grunow S. 
Published: June 2019

AbstractIn this work we report the adhesion of a thin Tantalum (Ta) barrier films deposited on nanoporous dielectric substrates (Xerogel and Methyl Silesquioxanes (MSQ)). The high compressive stresses in the Ta barrier layer lead to spontaneous delamination from the underlying substrate resulting in a telephone cord like morphology, which allows the measurement of critical interfacial adhesion (fracture) energy. The fracture energy of Ta barrier films on different porous substrates is evaluated using the above two methods and the resulting differences are explained. Fracture energy varies inversely as a power law with the dielectric pore size indicating pores are essential to delamination in the barrier-dielectric interface. The observed trend of fracture energy is related to other mechanical properties of the porous substrate offering insights into the underlying mechanisms governing fracture of films deposited on porous substrates.
Employing Thin Film Failure Mechanisms to Form Templates for Nano-electronics
Authors: Adelung Rainer , Elbahri Mady , Rudra Shiva Kumar , Biswas Abhijit , Jebril Seid , Kunz Rainer , Wille Sebastian , Scharnberg Michael 
Published: June 2019

AbstractRecently, we showed that thin film stresses can be used to form well aligned and complex nanowire structures [1]. Within this approach we used stress to introduce cracks in a thin film. Subsequent vacuum deposition of metal leads to the formation of a metal layer on the thin film and of metal nanowires in the cracks of the film. Removal of the thin film together with the excess metal cover finishes the nanowire fabrication on the substrate. As stress can be intentionally introduced by choosing an appropriate thin film geometry that leads to a stress concentration, the cracks and consequently the nanowires can be well aligned. Meanwhile, we have demonstrated how to form thousands of parallel aligned nanowires, x-and y-junctions or nanowires with macroscopic contacts for sensor applications, simply by applying fracture mechanics in thin films. Christiansen and Gösele called this approach “constructive destruction” in a comment in Nature Materials [2]. This gives a hint how to overcome some problems of the approach, arising from the limits of thin film fracture. A generalization of the fracture approach by being “more destructive” can overcome this limitations. For example, it is difficult to form pairs of parallel wires with a nanometer distance of the pair, but a micrometer separation between the individual pairs. Structures like this are useful for many contact applications including sensor arrays or field effect transistors. As well as thin film fracture, thin film delamination can be well controlled by fracture mechanics. Our latest experiments show that the combination of both, fracture and delamination, forms an ideal shadow mask for vacuum deposition. Cracks with delaminated sides were used as templates for the deposition of pairs of parallel wires consisting out of different materials with only a few 10 nm separation. First, a metal was sputter deposited under an angle of approx. 45° through the delaminated crack, which was used as a shadow mask. Afterwards, a second deposition metal is deposited under the opposite 45° angle with respect to the sample normal, having the crack located in the middle between both deposition sources. The angle, the delamination height and the crack width determine the separation of the nanowire contacts. We present several examples which show how these mechanisms of mechanical failure of thin films can be turned into useful templates for various nanostructures. We will focus here on two thin film systems, that can be easily deposited in every lab. These are wet chemically deposited photo-resist and flash evaporated amorphous carbon. These examples are compared with finite element simulations of the thin film stress with the ANSYS program. Moreover, we show how the delamination cracks can be also used as masks for the removal of material. Channals with a width down to 20 nm produced by ion beam sputtering are shown.
Comparison of Line Stress Predictions with Measured Electromigration Failure Times
Authors: Morusupalli Rao R. , Nix William D. , Patel Jamshed R. , Budiman Arief S. 
Published: June 2019

AbstractReliability of today's interconnect lines in microelectronic devices is critical to product lifetime. The metal interconnects are carriers of large current densities and mechanical stresses, which can cause void formation or metal extrusion into the passivation leading to failure. The modeling and simulation of stress evolution caused by electromigration in interconnect lines and vias can provide a means for predicting the time to failure of the device. A tool was developed using MathCAD for simulation of electromigration-induced stress in VLSI interconnect structures using a model of electromigration induced stress. This model solves the equations governing atomic diffusion and stress evolution in one dimension. A numerical solution scheme has been implemented to calculate the atomic fluxes and the evolution of mechanical stress in interconnects. The effects of line geometries and overhangs, material properties and electromigration stress conditions have been included in the simulation. The tool has been used to simulate electromigration-induced stress in pure Cu interconnects and a comparison of line stress predictions with measured electromigration failure times is studied. Two basic limiting cases were studied to place some bounds on the results. For a lower bound estimate of the stress it was assumed that the interface can be treated like a grain boundary in Cu. For an upper bound estimate it was assumed that the interface can be treated like a free surface of Cu. Existing data from experimental samples with known structure geometries and electromigration failure times were used to compare the electromigration failure times with predicted stress build-up in the interconnect lines.
Low temperature deposition of Indium tin oxide (ITO) films on plastic substrates
Authors: Singh Vandana , Saswat B. , Kumar Satyendra 
Published: June 2019

AbstractOrganic light emitting diodes (OLEDs) require a transparent conducting oxide (TCO) electrode for injection of charge carriers and the emitted light to come out. In order to exploit the full flexibility of organic semiconductor based large area electronic devices, the deposition of TCO on plastic substrates is essential, which prohibits high temperature processing. Therefore, low temperature deposition of Indium tin oxide (ITO) films is very important for flat panel displays and solar cells. Here we have carried out a systematic study of ITO deposition on plastic substrates using RF magnetron sputtering. For the optimization of structural, electrical and optical properties of ITO, various experiments such as X-ray diffractometer, transmission measurements, sheet resistance and AFM were employed. These properties were investigated as a function of substrate temperature, deposition time and RF power. From these experiments, we obtained a reasonably low sheet resistance (˜ 14;Ω / □) and high transmittance (˜75%) in the visible region on plastic substrates. We also observed that these films are not much affected by atmosphere and does not degrade with time. These ITO films deposited by RF magnetron sputtering on plastic substrates can be use as anode for flexible organic light emitting displays.
Surface Acoustic Wave-Induced Electroluminescence Intensity Oscillation in Planar Light-Emitting Devices
Authors: Cecchini Marco , Piazza Vincenzo , Beltram Fabio , Ward Martin , Shields Andrew , Beere Harvey , Ritchie David 
Published: June 2019

AbstractElectroluminescence (EL) emission controlled by means of surface acoustic waves (SAWs) in planar light-emitting diodes (pLEDs) is demonstrated. Interdigital transducers (IDTs) for SAW generation were integrated onto pLEDs fabricated following a scheme compatible with SAW propagation [1]. EL in presence of SAW was studied by time-correlated photon-counting techniques. We found intensity oscillation at the SAW frequency (˜1 GHz) demonstrating electron injection into the p-type region synchronous with the SAW wavefronts.
Fabrication of In2O3 Oxide Semiconductor Nano-Particles Using Apoferritin
Authors: Okuda Mitsuhiro , Yamashita Ichiro , Iwahori Kenji , Yoshimura Hideyuki 
Published: June 2019

AbstractIn2O3 nanoparticles were fabricated in the cavity of the cage-shaped protein, apoferritin by utilizing a quick chemical reaction of indium oxide. Horse spleen apoferritin in the solution of indium ions buffered at pH 9.5 was incubated for 30 minutes. The transmission electron microscopy (TEM) observation with aurothioglucose staining showed that cores were formed in the apoferritin cavity. The sizes of cores were regulated by the cavity size and their diameters were below 7nm. Energy dispersion X-ray analysis (EDX) indicated that indium was contained in the cores. The high-resolution TEM (HR-TEM) revealed that cores are single or poly crystalline and the lattice space was consistent with that of In2O3. These results confirmed that the In2O3 cores were successfully formed in the apoferritin cavity.