bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suppression of Staebler-Wronski Effect Induced Electrical Crosstalk in a-Si:H-Based Image Sensors
Authors: Theil Jeremy A. 
Published: April 2011

ABSTRACTHydrogenated amorphous silicon photodiodes have been considered for use in array-based image sensors. They promise to significantly reduce the size and cost of CMOS image sensors, while offering the promise of improved pixel sensitivity. However, Staebler-Wronski Effect (SWE) based electrical crosstalk degradation has been a major concern in their acceptance, due to degraded spatial contrast and color fidelity. Since the SWE is a fundamental mechanism of a Si:H, solutions to this issue must look to ways of mitigating the SWE on diode array performance rather than elimination of SWE. In order to study electrical crosstalk, a novel device structure that inhibits light from reaching portions of the a-Si:H/dielectric interface was designed and fabricated to directly measure interpixel leakage currents. Results from these structures indicate that edge leakage can be a significant contributing component to the measured signal. In addition, a CMOS-compatible structure to suppress electrical crosstalk was designed and fabricated. Results from these structures demonstrate suppression of crosstalk up to lateral electric fields of at least 2 x 104 V/cm. Such suppression is adequate for densely packed minimum-size pixel arrays. Aspects of the design and implementation of the structure will also be discussed.
Low Temperature (<150°C) Doping Techniques for Polysilicon TFT's
Authors: Hong W.S. , Kim J.M. , Han S.H. , Lee Y.H. , Kim Y.W. , Lee S.H. , Kim D.Y. 
Published: April 2011

ABSTRACTDoping of polysilicon (poly-Si) films was performed at a low temperature (<150°C), by using three different dopant incorporation methods: ion shower, dopant layer deposition and plasma immersion. All three techniques were shown to be capable of obtaining sheet resistance values that were smaller than 104 Ω/sq., which were considered to be sufficient to form good source-drain contacts. Also, a sheet resistance value that is as low as 300 Ω/sq. was demonstrated. It was found that the laser energy used for dopant activation was the major parameter to control the sheet resistance of the poly-Si films. The lowest attainable sheet resistance was not affected much by the ion dose, as long as the initial dose is higher than 1015 cm−2. The plasma immersion method was shown to be a good alternative to the ion shower, as the doping could be performed in a relatively short time without causing a structural damage to the poly-Si film.
Silicon-Hydrogen Bonds in Boron and Phosphorous Doped Polycrystalline Silicon Thin Films
Authors: Saleh R. , Nickel N. H. 
Published: April 2011

ABSTRACTHydrogen bonding in laser crystallized boron and phosphorous doped polycrystalline silicon is investigated using Raman spectroscopy and hydrogen effusion measurements. During laser crystallization the intensity of the local vibration modes near 2000 and 2100 cm−1 decreases. The intensity of vibration mode at 2000 cm−1 decreases faster than the one at 2100 cm−1. From H effusion measurements, the hydrogen density-of-states (H DOS) distribution is derived. For undoped amorphous silicon the H DOS exhibits two prominent peaks at hydrogen binding energies of E– μH = –1.1 and –1.5 eV. In B doped a-Si:H the peak at –1.1 eV is less pronounced while in P doped a-Si:H the H binding energy increases by about 0.1 eV. In all samples laser crystallization causes an increase of the H binding energy by about 0.2 – 0.3 eV. However, the peaks in the H DOS observed in B-doped samples are preserved during laser crystallization.
CW Argon-ion laser initiated aluminum induced crystallization of amorphous silicon thin films
Authors: Paduru Sampath K. , Abu-safe Husam H. , Naseem Hameed A. , Al-Shariah Adnan , Brown William D. 
Published: April 2011

ABSTRACTCW Argon-ion laser initiated aluminum induced crystallization (AIC) of RF magnetron sputtered amorphous silicon (a-Si) thin films has been investigated. It was found that lasers could be effectively used to initiate AIC process at very low threshold power densities. An argon-ion laser (λ=514.5 nm) was used to anneal Al/a-Si/glass structures with varying power densities ranging between 55 and 125 W/cm2 and exposure times ranging from 10 to 120 s. X-ray diffraction analysis showed the resulting films to be polycrystalline. The crystallization rate increased both with power density and exposure time. Environmental scanning electron microscopy (ESEM) analysis showed that the surface features change with increasing power density and irradiation time. A dendritic growth pattern was observed in the initial stages of interaction between the films. A strong crystalline Raman peak at around 520 cm-1 was observed in the Raman spectra of the crystallized samples.
Defect Densities, Diffusion Lengths and Device Physics in Nanocrystalline Si:H Solar Cells
Authors: Dalal Vikram L. , Sharma Puneet , Staab David , Noack Max , Han Keqin 
Published: April 2011

ABSTRACTWe report on the properties of nanocrystalline Si:H solar cells. The solar cells were of the p+nn+ type, with the n+ layer deposited first on a stainless steel substrates. The solar cells were prepared under high hydrogen dilution conditions using either ECR plasma deposition, or VHF diode plasma deposition processes. The deposition pressures were kept low, 5 mTorr in the ECR reactor and 50 mTorr in the VHF reactor. All the solar cells reported showed a high Raman ratio of crystalline to amorphous peaks. Properties such as dark current, deep level defects and shallow doping densities, and hole diffusion lengths were measured in these cells. It was found that the base layer was always n type, but that its doping could be changed by adding ppm levels of B during growth. A sufficient B doping even type converted the base layer to p type. It was found that there was a good one-to-one correlation between the shallow doping and deep level defects, suggesting that the same element, probably oxygen, is responsible for generating both shallow dopants and deep levels. The diffusion length of holes was measured in these cells using quantum efficiency vs. voltage techniques, and it was found that the diffusion length data could be explained very well by invoking trap-controlled recombination statistics. The dark I(V) curves could be represented by a standard diode model for highly crystalline materials, but as the degree of crystallinity was reduced, the diode factor increased. Voltage could be improved by reducing the crystallinity of the layer, but doing so resulted in a decrease in quantum efficiency in the infrared regions of the solar spectrum.
Protocrystalline Silicon at High Rate from Undiluted Silane
Authors: Schropp R.E.I. , Veen M.K. van , Werf C.H.M. van der , Williamson D.L. , Mahan A.H. 
Published: April 2011

ABSTRACTHot Wire Chemical Vapor Deposition (HWCVD) is shown to be a fast method for the deposition of protocrystalline silicon films from undiluted silane. Intrinsic silicon-hydrogen films (2 μm thick) have been deposited by HWCVD on plain stainless steel as well as on stainless steel precoated with a n-type doped microcrystalline silicon layer. In X-ray diffraction experiments, the linewidths of the first sharp peak (FSP) were 5.59 ± 0.09 degrees and 5.29 ± 0.11 degrees, respectively, indicating improved medium-range order and a template effect due to the μc-Si:H n-layer. For thinner layers (0.7 μm thick), the linewidths of the FSP were 5.29 ± 0.09 degrees and 5.10 ± 0.09 degrees. These FSPs are as narrow as for optimized i-layers made by H2-diluted plasma deposition, however, at a much higher deposition rate (1 nm/s), at moderate temperature (250°C), and without the use of H2 dilution. In accompanying transmission electron micro-graphs, the layers show a significant concentration of elongated small voids in the growth direction that are not interconnected. Small Angle X-ray Scattering (SAXS) results are consistent with these observations. We suspect that the void nature allows the bulk of the film to be more ordered. The utilization of such layers in n-i- p solar cells on plain stainless steel leads to cells with a remarkably good stability, showing a decrease of the fill factor of less than 10 % during 1500 h of light soaking.
Understanding the structure of Si nanoclusters in a/nc-Si:H films using spherical aberration-corrected transmission electron microscopy
Authors: Perrey Christopher R. , Thompson Siri S. , Lentzen Markus , Kortshagen Uwe , Carter C. Barry 
Published: April 2011

ABSTRACTRecent work has shown that the electrical properties of hydrogenated amorphous Si films with nanocrystalline inclusions (a/nc-Si:H) make this material a promising candidate for applications in solar cells. The present study applies the technique of spherical aberration-corrected high-resolution transmission electron microscopy for the identification and analysis of the crystalline content of an a/nc-Si:H film. By varying both the spherical aberration of the objective lens and the defocus, regions of crystallinity in the a/nc-Si:H film can be identified. This study reports the analysis of Si nanoparticles of approximately 1.5 nm in size. Some of these nanoparticles contain planar defects, such as twin defects and stacking faults. All particles observed were the same crystal structure as bulk Si, which agrees with theoretical cluster calculations. Beam damage was observed in the amorphous matrix for long electron–beam exposures.
Formation of periodic grain boundary in an Si thin film crystallized by a linearly polarized Nd:YAG pulse laser with an ultra sonic oscillator
Authors: Kaki Hirokazu , Ootani Takehiko , Horita Susumu 
Published: April 2011

ABSTRACTIn order to obtain a large silicon (Si) grain and to control the location of its boundary in a Si film melting-crystallized by a pulse laser, we have proposed to use periodic thermal distribution spontaneously induced by irradiation of a linearly polarized laser beam. We estimated the suitable amorphous Si (a-Si) thickness taking account of multiple reflection theoretically and confirmed it experimentally. Also, we proposed a novel technique to reduce the irradiation pulse number to control the grain boundary location stably in the crystallized Si film, in which the elastic wave was generated on the surface of a-Si film prior to melting-crystallization by using an ultra sonic oscillator. Owing to this technique, we can control the grain boundary location periodically with only 1 pulse irradiation in the crystallized Si film.
A photothermal method of simultaneous determination of ultra-shallow junction depth and abruptness
Authors: Salnick Alex , Nicolaides Lena , Opsal Jon , Jain Amitabh , Rogers Duncan , Robertson Lance 
Published: April 2011

ABSTRACTThermal wave (TW) studies of ultra-shallow junctions (USJ) formed by ion implantation into a semiconductor wafer followed by rapid thermal annealing (RTP) are described. It is shown that using the TW technique allows for a simultaneous determination of the most important USJ parameters – depth and profile abruptness. Experimental results for junction depth and abruptness obtained on a set of B+-implanted, RTP-annealed USJ samples show better than 0.99 correlations to the corresponding secondary ion mass spectroscopy (SIMS) data.
Ultra-Shallow Junction Formation Technology from the 130 to the 45 nm node
Authors: Jain Amitabh 
Published: April 2011

ABSTRACTOne of the main materials challenges of the 130 nm silicon technology node was the need to find a processing solution to the anomalous diffusion behavior of ion-implanted dopants known from three decades of research. Reduction of implantation energy no longer proved sufficient when trying to reduce source/drain extension junction depth, increase abruptness, and limit sheet resistance. Spike-annealing, a new process in which ion implanted silicon could be heated rapidly to temperatures required for dopant activation and then cooled down without dwelling at temperature, adequately addressed the scaling requirements of this node. The resulting junctions achieved high dopant concentration values very close to the surface while limiting junction depth. However, this increased the propensity for dopant migration to overlying layers associated with the source/drain spacer. Loss of device performance due to this and other phenomena became a strong motivating factor for further materials research in order to sustain progress through the 130 nm and 90 nm nodes. Complex interactions between various layers have been understood and the resulting developments in spacer materials have enabled high performance devices. The requirements of the 65 and 45 nm nodes stretch spike-annealing to its limit and newer Ultra-High Temperature anneals must be considered.
Optimization of Fluorine Co-implantation for PMOS Source and Drain Extension Formation for 65nm Technology Node
Authors: Graoui H. , Hilkene M. , McComb B. , Castle M. , Felch S. , Cowern N.E.B. , Al-Bayati A. , Tjandra A. , Foad M. A. 
Published: April 2011

ABSTRACTThe main challenges for PMOS ultra shallow junction formation remain the transient enhanced diffusion (TED) and the solid solubility limit of boron in silicon. It has been demonstrated that low energy boron implantation and spike annealing are key in meeting the 90 nm technology node ITRS requirements. To meet the 65 nm technology requirements many studies have used fluorine co-implantation with boron and Si+ or Ge+ pre-amorphization (PAI) and spike annealing. Although using BF+2 can be attractive for its high throughput, self-amorphization and the presence of fluorine, many studies have shown that for the fluorine to successfully reduce TED its energy needs to be well optimized with respect to the boron's, therefore BF+2 does not present the right fluorine/boron energy ratio for the optimum junction formation. In this work we optimize the fluorine energy when a deep or shallow PAI is used. We also demonstrate that the fluorine dose needs to be carefully optimized otherwise a reverse effect can be observed. We will also show that the optimized junction depends less on the Ge+ energies between 2 keV and 20 keV and when HF etch is implemented after Ge+ PAI, improvements in both the junction depth and the sheet resistance are observed.
Suppression of Boron Diffusion by Fluorine Implantation in Preamorphized Silicon
Authors: Impellizzeri Giuliana , dos Santos José H. R. , Mirabella Salvatore , Priolo Francesco , Napolitani Enrico , Carnera Alberto 
Published: April 2011

ABSTRACTWe have investigated the role of fluorine in the reduction of transient enhanced diffusion (TED) and thermal diffusion (TD) of B in preamorphized Si layers implanted with F. For this purpose, we have employed B delta-doped layers, grown by molecular beam epitaxy (MBE), as markers for silicon self-interstitials (Is). We have shown that boron TED decreases with increasing amount of incorporated F up to the complete TED suppression. Furthermore, we have clearly demonstrated that the physical mechanism that suppresses the boron TED is not a B-F chemical bonding, but a strong interaction between F atoms and Is. In addition, we have seen that fluorine strongly reduces B diffusion also under Is thermal equilibrium concentration. Our results clearly show that the presence of F lowers the Is density very effectively, reducing the boron TED as well as the dopant diffusion under equilibrium conditions.
Atomistic Analysis of the Role of Silicon Interstitials in Boron Cluster Dissolution
Authors: Aboy Maria , Pelaz Lourdes , Marqués Luis A. , López Pedro , Barbolla Juan 
Published: April 2011

ABSTRACTBoron implantation into preamorphized Si, followed by low temperature solid phase epitaxial (SPE) regrowth produces high activation combined with low diffusion. However, in the presence of high B concentrations, the activation obtained after the SPE regrowth only can reach concentrations in the order of a few times 1020 cm−3, and even more deactivation occurs during additional annealing. We have analyzed the role of the Si interstitials injected from the end of range (EOR) damage in B deactivation and reactivation by atomistic simulations. We have shown that the B cluster evolution can be clearly correlated to the evolution of Si interstitial defects at EOR. This is also compatible with B cluster stabilization in the presence of excess Si interstitials, observed in oxidation experiments.
Concentration Dependence of Boron-Interstitial Cluster (BIC) Formation in Silicon-on-Insulator (SOI)
Authors: Saavedra A. F. , Jones K. S. , Radic L. , Law M. E. , Chan K. K. 
Published: April 2011

ABSTRACTThe effect of boron concentration on boron-interstitial cluster (BIC) dissolution was studied in separation by implantation of oxygen (SIMOX) and SOITEC silicon-on- insulator (SOI) materials. SOI substrates having surface silicon thickness of 750 Å and 1450 Å were ion implanted with 11B+ at a energy of 15 keV. The dose of the implant was varied from 3×1014 cm−2 to 1×1015 cm−2 to provide different boron peak concentrations. Anneals were performed at 825 °C in a nitrogen ambient using RTA for short times and furnace anneals for longer times. The retained dose of boron in the surface silicon layer was estimated using simulations from UT-Marlowe 5.0. Hall Effect was used to measure the sheet resistance, mobility, sheet number, and fraction of active boron. At lower concentrations, SOI exhibited significantly lower sheet numbers. As the boron concentration was increased SOI began to approach bulk Si. However, degraded mobility and sheet resistance was observed at all concentrations. Truncating the boron profile over the surface Si/buried oxide interface enhanced the fraction of active boron in the 750 Å SOI. This also lead to a higher fractional activation in 750 Å SOI than bulk Si as the concentration increased due to a loss of interstitials, effectively reducing the BIC population.
Deposition and Integration of a Novel Ultra-Low k (2.2) Material
Authors: Schulberg Michelle T. , Humayun Raashina , Sengupta Archita , Sun Jia-Ning 
Published: April 2011

AbstractIncreasing demands for faster chip speed and reduced power consumption are driving the semiconductor industry to develop insulating layers with lower dielectric constants. As the dielectric constant of a material is reduced, however, it becomes increasingly difficult to achieve the mechanical strength required to manufacture a multilevel interconnect. A new route to the synthesis of mesoporous silica has been demonstrated on 200 mm wafers. Silicate precursors dissolved in supercritical CO2 are infused into a block copolymer film. The polymer is then removed, but the resulting porous SiO2 replicates its ordered structure, enhancing the strength of the network. Incorporation of alkyl silicates further improves the film properties. Post-treatment to cap residual silanol groups renders the surface of the film hydrophobic and stabilizes it to air exposure. By appropriate choice of the block copolymer and other process parameters, the pore size and density can be varied and k values as low as 1.8 can be achieved. For a film with a dielectric constant of 2.25, the pore size is ∼4 nm. The hardness and modulus are 1.1 GPa and 7.8 GPa, respectively, as measured by nanoindentation. Four-point bend measurements yield fracture energies of 9.8 J/m2. More importantly, the film can withstand chemical mechanical planarization (CMP) using standard oxide polishing conditions.
Polyimide as a Plastic Substrate for the Flexible Organic Electroluminescent Device
Authors: Park Jin-Woo , Kim Youngkyoo , Lim Hyuntaek , Bae Cheol Min , Kim Il , Ando Shinji , Ha Chang-Sik 
Published: April 2011

AbstractIn this work, transparent flexible substrates based on polyimides(PI) with indium tin oxide (ITO) thin films for organic electroluminescent devices have been prepared. 2,2'-bis-(3,4- dicarboxyphenyl) hexafluoropropanedianhydride (6FDA) and 2,2'-bis-(trifluoromethyl)-4,4'- diaminobiphenyl (TFDB) PI films were used for transparent flexible substrates. ITO thin films were prepared at two substrate deposition temperatures of 25°C and 150°C with a typical radio- frequency (r.f.) planar magnetron sputtering system. The sheet resistance and the optical transmission properties of the fluorinated PI substrate were comparable with those for the slide glass substrate. The substrate properties are better when the deposition temperature is higher. SiO2 coating onto the fluorinated PI substrate by sol-gel reaction was also attempted to improve the optical transmission of the ITO/PI substrate. It was found that the coating of SiO2 affected on the morphology of the PI substrates.
Roll-to-Roll Processes for the Manufacturing of Patterned Conductive Electrodes on Flexible Substrates
Authors: Chaug Y.S. , Haubrich Jeanne E. , Sereda Mike , Liang R.C. 
Published: April 2011

AbstractSimple, cost-effective roll-to-roll processes for the manufacturing of patterned conductor films have been developed. The technique involves printing proprietary masking patterns, depositing conductive material, and stripping away undesired areas. In one approach, a pattern is printed on the plastic substrate with a masking coating. Then, conductive material is deposited on the patterned substrate and the undesired areas are stripped away, leaving behind the patterned electrode structures. In another approach, a first masking pattern is printed, followed by a second masking coating which is repelled by the first masking layer and forms the negative pattern. The first masking pattern is stripped off, a conductive layer is deposited, and the second masking pattern is stripped off, leaving a high resolution conductor pattern on the web. No photolithographic exposure, development or chemical etching is needed. These processes are useful for producing rolls of electrodes with features as small as 25 microns for the roll-to-roll manufacturing of flexible display applications.
Flexible electronics for space applications
Authors: Brandon Erik , West William , Zhou Lisong , Jackson Tom , Theriot Greg , Devine Rod A.B. , Binkley David , Verma Nikhil , Crawford Robert 
Published: April 2011

AbstractNASA is currently developing a host of deployable structures for the exploration of space. These include balloons, solar sails, space-borne telescopes and membrane-based synthetic aperture radar. Each of these applications is driven by the need for a thin, low mass, large area structure (e.g., polymer-based) which could not be implemented using conventional engineering materials such as metals and alloys. In each case, there is also the need to integrate sensing and control electronics within the structure. However, conventional silicon-based electronics are difficult to integrate with such large, thin structures, due to a variety of concerns including mass, reliability and manufacturing issues. Flexible electronics, particularly thin film transistors (TFTs), are a potentially key enabling technology that may allow the integration of a wide range of sensors and actuators into these types of structures. There are numerous challenges, however, regarding the survivability of such devices during stowage and deployment of the structure, as well as during operation in the harsh environments of space. We have fabricated TFTs on polyimide substrates, and are investigating the durability of these devices with respect to relevant space environments. We are also developing flexible sensor technologies for the integration of distributed sensor networks on large area structures.