bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Design, Implementation and Assessment of an On-Line, Open-Book Quizzing Environment for an Introductory Materials Science Course.
Authors: Locklin Ralph H , Howell Paul R 
Published: April 2011

AbstractThe authors have developed, implemented and assessed an on-line, open-book quizzing environment for the introductory materials science course, “Materials In Today’s World”. The course is offered as an E-Education course and students may complete the course from anywhere that permits access to our course management system, ANGEL. For reasons that were both pragmatic and philosophical, we decided that the exams/quizzes would not be proctored, they would be delivered wholly on-line, and would be open-book.In the current paper, we will present and justify our philosophy, of on-line, open-book quizzes: the rich feedback, which is a feature or our quizzing system, QuestionMark Perception, is used both as a teaching tool, and as a means to refine the quiz database. We have replaced the original “high-stakes” midterm and final exam, with a series of lower-stakes, weekly quizzes, which are generated from a large question database. Student response to the quizzing environment is generally very positive.
The Molecule, The Monomer and Materials Science: A Preliminary Report
Authors: Howell Paul 
Published: April 2011

AbstractThere would appear to be a large disconnect between the content of a typical high school chemistry course, and an introductory, college materials science course. For example, A National Science Foundation report notes that,“the historic bias of chemistry curricula towards small molecule chemistry, generally in the gaseous and liquid states, is out of touch with current opportunities for chemists in research, education and technology”.In contrast, the typical introductory college materials science course concentrates almost exclusively on the solid state, and a discussion of “small molecular” materials is virtually absent.In the present contribution, it will be shown how the “molecule” forms part of a hierarchical series of structures, from the sub-atomic to the macroscopic. It will also be argued that the molecule is but a sub-set of a localized grouping of atoms, which is best described by the term “monomer”.Based on a strict definition of the molecule and monomer, a complete hierarchical scheme for the structure of materials is developed, which should be applicable to both a high school chemistry course, and an introductory materials science course.
Thin Films of GeC Deposited Using a Unique Hollow Cathode Sputtering Technique
Authors: Huguenin-Love James L. , Soukup Rodney J. , Ianno Natale J. , Schrader Jason S. , Dalal Vikram L. 
Published: April 2011

AbstractExperimental results on thin films of the new material GexC1-x, deposited by a unique dual plasma hollow cathode sputtering technique are presented here. The (Ge, C) system is extremely promising since the addition of C to Ge has reduced the lattice dimensions enough to allow a lattice match to silicon, while increasing the bandgap close to that of c-Si. The sputtering is accomplished by igniting a dc plasma of the Ar and H2 gases which are fed through Ge and C nozzles, cylindrical tubes 30 mm in length with an 8 mm O.D. and a 3 mm I.D.The basic material, optical, and structural properties were analyzed. Film characterization was performed using Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Auger electron spectroscopy. Additional measurements such as Tauc bandgap, conductivity as a function of temperature and light intensity, and film uniformity have been made. The film properties from a variety of deposition conditions are discussed. The measurements made indicate that the films can be grown so that the C enters the material at lattice sites. In addition, the GexC1-x films absorb photons much more efficiently than either c-Si or c-Ge.Initial results on Al doped films are presented.
Incubation Layer-Free Nanocrystalline-Si Thin Film Fabricated by ICP-CVD at 150°C for Flexible Electronics
Authors: Han Sang-Myeon , Cha Young-Kwan , Park Joong-Hyun , Park Sang-Geun , Park YoungSoo , Han Min-Koo 
Published: April 2011

AbstractThe nc-Si films where the troublesome incubation layer was almost eliminated were deposited by inductively coupled plasma chemical vapor deposition (ICP-CVD) under various dilution conditions. The nc-Si films were analyzed with cross-sectional high resolution transmission electron microscopy (HR-TEM) images. It was verified that the Si crystalline components formed and grew from the surface of buffer layer. The grain size of 20~50nm was measured. The absence of incubation layer in nc-Si film may be attributed mainly to ICP-CVD which generates remote plasma of high density, the role of hydrogen, and the dilution effect on the growth of crystalline. Our experimental results show that incubation-free nc-Si film deposited by ICP-CVD may be suitable for the active layer of bottom gate nc-Si TFTs as well as top gate nc-Si TFTs.
Effects of HWCVD-deposited Seed Layers on Hydrogenated Microcrystalline Silicon Films on Glass Substrates
Authors: Adachi Michael Musashi , Tse Wing Fai Lydia , Cluff Garnet , Kavanagh Karen L. , Karim Karim S. 
Published: April 2011

AbstractMicrocrystalline silicon was deposited by hot-wire chemical vapor deposition (HWCVD) using a graphite filament with and without a thin 50 nm microcrystalline silicon seed layer. Increasing silane concentration diluted in H2 led to a decrease in crystalline fraction as well in a decrease in dark conductivity and photo-conductivity. In addition, films deposited with a seed layer were found to have higher dark conductivity and photo-conductivity than those without a seed layer but deposited at slower growth rates. However, Raman spectroscopy showed that use of a seed layer resulted in only a small increase in crystalline fraction at the surface of the films which had thicknesses between 250-400nm. TEM measurements confirmed the crystalline nature of deposited films showing average grain sizes of 25 nm.
Experimental Studies of Photoluminescence in Mn-Ion Implanted Silicon Rich Oxide Thin Film
Authors: Pan Wei , Dunn R.G. , Carroll M.S. , Wang Y.Q. 
Published: April 2011

AbstractIn this paper, we wish to report our preliminary experimental results from the photoluminescence (PL) studies in a Mn-ion implanted silicon-rich oxide (SRO) thin film. At 4 K, a broad PL peak, centered at ~ 1.2 eV, was observed. It is blue-shifted from the Si substrate peak at ~ 1.1 eV. The temperature (T) dependence of PL was carried out at zero magnetic (B) field and B = 0.5 Tesla, respectively, and showed quantitatively different behaviors. At B = 0, the PL intensity increases very slowly at low temperatures and reaches a maximal value at ~ 40 K. It then decreases as T is further increased. At B = 0.5 Tesla, the peak temperature (Tpeak), whether the intensity is maximal, moves to ~ 80-100 K, and the decreasing rate beyond Tpeak is much smaller than that at B = 0. We speculate that these two different behaviors might reveal, possibly, a ferromagnetic ordering in Mn-ion doped silicon nanocrystals.
The Investigation of High Performance TFT by Thin Beam Directional X-stallization Method
Authors: Chao Chihwei , Peng Jiatien , Cheng CW , Chen Chunghung , Turk Brandon A. , Burfeindt Bernd 
Published: April 2011

AbstractThin-beam directional X'tallization (TDX) is a low-temperature-substrate compatible crystallization method that can form directionally solidified poly-si films directly on glass substrates. Without using a mask, extremely long uniformly-spaced poly-Si grains can be formed by TDX. In this paper, we have investigated the influence of laser energy and scan pitch on the properties of the resulting poly-Si films. Grain size and surface morphology of TDX-processed poly-Si films were observed by SEM and AFM. The AFM results demonstrate that, due to the lateral growth phenomenon, TDX poly-Si films are much smoother than films produced by the current industry standard method, Excimer Laser Annealing (ELA). The breakdown of the TDX method is also discussed in this paper. When the laser scan pitch is larger than the lateral growth length that is characteristic of a given poly-Si film and beam property combination, a discontinuous poly-Si film is formed with vertical protrusions and grain boundaries occurring perpendicular to the scan direction. Poly-Si films with vertical protrusions and grain boundaries perpendicular to the direction of current flow will degrade the resulting thin-film transistor (TFT) performance.
Backplane Requirements for Active Matrix Organic Light Emitting Diode Displays
Authors: Nathan Arokia , Striakhilev Denis , Chaji Reza , Ashtiani Shahin , Lee Czang-Ho , Sazonov Andrei , Robertson John , Milne William 
Published: April 2011

AbstractOrganic light emitting diode (OLED) displays are a serious competitor to liquid crystal displays in view of their superior picture quality, higher contrast, faster on/off response, thinner profile, and high power efficiency. For large area and/or high-resolution applications, an active matrix OLED (AMOLED) addressing scheme is vital. The active matrix backplane can be made with amorphous silicon (a-Si), polysilicon, or organic technology, all of which suffer from threshold voltage shift and/or mismatch problems, causing temporal or spatial variations in the OLED brightness. In addition, the efficiency of the OLED itself degrades over time. Despite these shortcomings, there has been considerable progress in development of AMOLED displays using circuit solutions engineered to provide stable and uniform brightness. Indeed the design of AMOLED pixel circuits, particularly in low-mobility TFT technologies such as a-Si, is challenging due to the stringent requirements of timing, current matching, and low voltage operation. While circuit solutions are necessary, they are not sufficient. Process improvements to enhance TFT performance are becoming inevitable. This paper will review pertinent material requirements of AMOLED backplanes along with design considerations that address pixel architecture, contact resistance, and more importantly, the threshold voltage stability and associated gate overdrive voltage. In particular, we address the question of whether conventional PECVD can be deployed for high mobility and high stability TFTs, and if micro-/nano-crystalline silicon could provide the solution.
Effect of Light Illumination on Threshold Voltage and Sub-threshold Slope of Amorphous Silicon Thin Film Transistors
Authors: Jiao Lihong , Wronski Christopher R. , Jackson Thomas N. 
Published: April 2011

AbstractIn this study the light induced defect state creation under 1 sun illumination is investigated through changes in sub-threshold slope, Δ, and threshold voltage, VT, in a-Si:H TFT structures. Threshold voltage changes can be due to either charge trapping or defect state creation near the interface of gate insulator and a-Si:H active layer. By incorporating high quality thermal silicon dioxide in the a-Si:H TFT, the charge trapping effects have been minimized and the changes in threshold voltage can be attributed to induced defect states in the a-Si:H. Since the sub-threshold current is closely related to the band gap defect states, both VT and Δ can be used as a new probe to study the light induced defect creation in the a-Si:H. The information obtained about the nature of gap defect states from the analysis of changes in VT and Δ under light illumination is presented. The results obtained show that under 1 sun illumination there are very fast increases (within 10 seconds) in VT with subsequent slow increases and no observable changes in Δ, similar to those observed in the light induced photoconductivity changes in a-Si:H thin films. The increase in VT under the initial light illumination are associated with the Fermi level in a-Si:H active layers moving downward and causing band bending near the interface region of the gate insulator and a-Si:H active layer. Results are also presented on changes in VT under gate-bias stressing. Comparisons are then made between the results obtained under 1 sun light illumination and those under gate-bias stressing. The information obtained in this study about the nature of the gap defect states derived from characterization of the sub-threshold regimes is discussed.
Metal-Induced Nickel Silicide Nanowire Growth Mechanism in the Solid State Reaction
Authors: Kim Joondong , Bae Jong-Uk , Anderson Wayne A. , Kim Hyun-Mi , Kim Ki-Bum 
Published: April 2011

AbstractA unique nanowire growth was accomplished at 575 oC by the metal-induced growth (MIG). That is a spontaneous reaction between metal and Si. The deposited metal worked as a catalyst layer to grow nanowire in the solid-state. Various metals (Ni, Co, and Pd) were used in MIG nanowire fabrication and Ni-induced case was successful in demonstrating that metal species should be a dominant mover in nanowire growth. Transmission electron microscopy investigation was performed to observe the nanowire growth direction. The Ni to Si composition was studied by energy dispersive spectroscopy showing the Ni diffusion inside the nanowire as well as the Ni silicide layer. The practical application MIG nanowire was proven by fabricating nanoscale contacts.
Local Current Flow in Mixed-Phase Silicon Solar Cells and Correlation to Light-Induced Open-Circuit Voltage Enhancement
Authors: Yan Baojie , Jiang C.-S. , Moutinho H. R. , Al-Jassim M. M. , Yang Jeffrey , Guha Subhendu 
Published: April 2011

AbstractWe use conductive atomic force microscopy (C-AFM) to measure the local current flow in the mixed-phase hydrogenated silicon n-i-p solar cell structure without the top ITO contact. The forward biased C-AFM images reveal that for the fully amorphous region the current is very low on the entire surface. However, high current spikes appear in the mixed-phase region, where the current spikes are correlated to the formation of nanocrystallite aggregations with a diameter of ~500 nm. Furthermore, the density of the current spikes increases from the mixed-phase to the substantially nanocrystalline regions. The nanocrystallite aggregation supports our previously proposed parallel-connected two-diode model for Voc drops with crystalline volume fraction and light-induced Voc increase in the mixed-phase solar cells. Adding a 50-nm thick a-Si:H buffer layer between the p and i layers significantly reduces the magnitude of the high current spikes, even the top morphology appears unaffected. This result is also consistent with the previously proposed two-diode model for explaining the carrier transport in the mixed-phase solar cells.
Production Technologies of Film Solar Cell
Authors: Takano Akihiro , Tabuchi Katsuya , Uno Masayoshi , Tanda Masayuki , Wada Takehito , Shimosawa Makoto , Sakakibara Yasushi , Kiyofuji Shinji , Nishihara Hironori , Enomoto Hirofumi , Kamoshita Tomoyoshi 
Published: April 2011

AbstractLight-weight, large-area and flexible solar cells and modules were developed. Roll-to-roll processes including an improved film deposition process named “Stepping-roll process” are used to fabricate large-area hydrogenated amorphous silicon-based solar cells in succession on plastic film substrates. A unique device having through-hole contacts was developed and applied to simplify the production processes and to generate high voltage using connection in series. Production technologies, such as (1) light-weight and large area module fabrication, (2) plasma condition controlled chemical vapor deposition, (3) low substrate temperature selective reactive sputtering, and (4) large-area uniform transparent conductive oxide film deposition are reviewed.
Highly Efficient Microcrystalline Silicon Solar Cells Deposited from a Pure SiH4 Flow
Authors: van den Donker Menno , Rech B. , Schmitz R. , Klomfass J. , Dingemans G. , Finger F. , Houben L. , Kessels W.M.M. , van de Sanden M.C.M. 
Published: April 2011

AbstractThe effect of conventional process parameters on the deposition of μc-Si:H solar cells is reviewed. Then, an approach to solar cell optimization is presented in which hidden, internal parameters are adjusted rather than conventional, external process parameters. The investigation focuses on deposition at low H2 dilution ratio and low total gas flow. A hidden parameter is identified through time resolved optical emission spectroscopy on SiH emission: Transient depletion of the SiH4 source gas leads to uncontrolled deposition conditions during the first 90 s after plasma ignition. There hardly is any effect on plasma properties and deposited film properties for the remainder of deposition after the transient depletion phase. As demonstrator a 9.5 % efficient single junction μc-Si:H solar cell was deposited from a pure SiH4 flow. A reinterpretation of the role of H2 dilution is discussed.
Ge out-diffusion and its Effect on Electrical Properties in s-Si/SiGe Devices
Authors: Uppal Suresh , Kanoun Mehdi , Chattopadhyay Sanatan , Agaiby Rimoon , Olsen Sarah H. , Bull Steve J. , O'Neill Anthony 
Published: April 2011

AbstractIn this paper we report on the quantification of Ge diffusion in strained Si/SiGe (s-Si/SiGe) structures for different Ge content in the SiGe virtual substrate. Using TCAD tools, the diffusivity has been calculated by varying pre-exponential factor and activation energy for Ge diffusion in s-Si and SiGe layers separately and obtaining a fit to the SIMS profiles. We observe an exponential and a linear dependence of pre-factor and activation energy for Ge diffusion in s-Si and SiGe, respectively, which is in agreement with literature. As a result of diffusion, the carrier confinement in thin strained layer reduces and the mobility is affected. Using C-V measurements on MOS capacitors fabricated along with devices, a shift in the flat band voltage has been observed and is attributed to a change in the interface trapped and fixed oxide charge. We observe a stronger effect of the variation of strained layer thickness than Ge content on the change in the flatband voltage. This observation is consistent with an exponential increase in Ge arriving at the interface with decrease in strained layer thickness.
Interaction Between Low Temperatures Spacers and Source Drain Extensions and Pockets for Both NMOS and PMOS of the 65 nm Node Technology
Authors: Cagnat Nathalie , Laviron Cyrille , Mathiot Daniel , Morin Pierre , Salvetti Frédéric , Villanueva Davy , Juhel Marc , Hopstaken Marco , Wacquant François 
Published: April 2011

AbstractDuring the MOS transistors fabrication process, the source-drain extension areas are directly in contact with the oxide liner of the spacers stack. In previous works [1, 2, 3] it has been established that boron can diffuse from the source-drain extensions into the spacer oxide liner during the subsequent annealing steps, and that the amount of boron loss depends on the hydrogen content in the oxide, because it enhances B diffusivity in SiO2.In order to characterize and quantify the above phenomena, we performed test experiments on full sheet samples, which mimic either BF2 source-drain extensions over arsenic pockets implants, or BF2 pockets under arsenic or phosphorus source-drain extensions implants. Following the corresponding implants, the wafers were covered with different spacer stacks (oxide + nitride) deposited either by LPCVD, or PECVD. After appropriate activation annealing steps, SIMS measurements were used to characterize the profiles of the various dopants, and the corresponding dose loss was evaluated for each species.Our experimental results clearly evidence that LPCVD or PECVD spacer stacks have no influence on the arsenic profiles. On the other hand, phosphorus and boron profiles are affected. For boron profiles, each spacer type has a different influence. It is also shown that boron out-diffuses not only from the B doped source-drain extension in direct contact with the oxide layer, but also from the "buried" B pockets lying under n-doped source drain extension areas. All these results are discussed in term of the possible relevant mechanism.
The Behavior of Ion Implanted Silicon During Ultra-High Temperature Annealing
Authors: Jain Amitabh 
Published: April 2011

AbstractUltra-high temperature annealing is emerging as a promising technique for annealing ion implanted layers with a view to maximizing electrical activation while minimizing dopant diffusion. In order to ensure successful implementation, several materials-related problems have been under study. Since the time scale of the process is short, diffusion in the amorphous phase may dominate the final profile. In general, the residual disorder after anneal can be higher than with current anneal processes. However, the short time scale of the process curtails the opportunity for movement of dislocations into regions where the electrical behavior of a device would be affected. An additional effect of the limited time scale is the ability of silicon to plasto-elastically support the high strain-rates that may arise during the anneal.
Electrical Characterization of Residual Implantation-Induced Defects in the Vicinity of Laser-Annealed Implanted Ultrashallow Junctions
Authors: Gonda V. , Liu S. , Scholtes T.L.M. , Nanver L.K. 
Published: April 2011

AbstractUltrashallow junctions (USJ) were created by tilted 5 keV As+ implantation to a dose of 3x1015 cm−2 followed by excimer laser annealing (ELA). Sheet resistance and capacitances were measured in the background layer below the USJ. Results showed that sheet resistance was dependent on the laser energies in the close vicinity of these diodes. Doping profiles extracted from the capacitances indicated electrical deactivation here caused by the residual implantation defects. The extent and location of the residual damage is shown to be strongly dependent on the implantation dose and tilt angles, and also influenced by the laser annealing.
Modeling and Experiments of Boron Diffusion During Sub-Millisecond Non-Melt Laser Annealing in Silicon
Authors: Noda Taiji , Felch Susan , Parihar Vijay , Vrancken Christa , Janssens Tom , Bender Hugo , Vandervorst Wilfried 
Published: April 2011

AbstractBoron diffusion and defect evolution during sub-millisecond (ms) laser annealing with partial SPER are investigated using secondary ion mass spectrometry and transmission electron microscopy. Boron diffusivity enhancement in amorphous-Si is observed during partial SPER at 550 °C. It is shown that boron diffusion during the laser annealing process is a 2-step diffusion (SPER + Laser). The depth of the amorphous layer affects the dopant activation behavior. During sub-ms laser annealing, end-of-range defects are formed and show an evolution behavior. {311} defects cannot completely transfer to dislocation loops after 1300 °C laser annealing. It is considered that the thermal budget of sub-ms laser is too small for full defect evolution. Atomistic diffusion modeling using a kinetic Monte Carlo method can explain the defect behavior during laser annealing.