bluuebunny/crossref_metadata_2025 huggingface dataset:
A SYSTEM MAINTENANCE PROCESS FOR FACILIATING REQUESTS MANAGEMENT AND CONFLICTS RESOLUTION
Authors: LIU CHI-LUN , YANG HENG-LI
Published: March 2011

Managing maintenance requests in information systems from stakeholders has been relatively neglected by academic researchers. This study proposes Enhancive Request Management (ERM), a method of managing enhancive requests from multiple stakeholders. The proposed method, based on hermeneutics, includes request formation, feedback, and conflict resolution processes. The request formation process is designed to handle the maintenance requests. The feedback process controls the changes of request formation results. And the conflict resolution process deals with diverse opinions. Besides, this work introduces a blog-based tool to support ERM. Two companies have tried this tool and provided some usage opinions. The empirical data reveals that the ERM methodology can improve request management works.
USING RULE STRUCTURE TO EVALUATE THE COMPLETENESS OF RULE-BASED SYSTEM TESTING: A CASE STUDY
Authors: MEDDERS STEPHEN C. , ALLEN EDWARD B. , LUKE EDWARD A.
Published: March 2011

Rule-based systems are typically tested using a set of inputs which will produce known outputs. However, one does not know how thoroughly the software has been exercised. Traditional test-coverage metrics do not account for the dynamic data-driven flow of control in rule-based systems. Our literature review found that there has been little prior work on coverage metrics for rule-based systems. This paper proposes test-coverage metrics for rule-based systems derived from metrics defined by prior work, and presents an industrial scale case study.

We conducted a case study to evaluate the practicality and usefulness of the proposed metrics. The case study applied the metrics to a system for computational fluid-dynamics models based on a rule-based application framework. These models were tested using a regression-test suite. The data-flow structure built by the application framework, along with the regression-test suite, provided case-study data. The test suite was evaluated against three kinds of coverage. The measurements indicated that complete coverage was not achieved, even at the lowest level definition. Lists of rules not covered provided insight into how to improve the test suite. The case study illustrated that structural coverage measures can be utilized to measure the completeness of rule-based system testing.
FORMAL ANALYSIS OF BPMN MODELS: A NuSMV-BASED APPROACH
Authors: LAM VITUS S. W.
Published: March 2011

Business Process Modeling Notation (BPMN) plays a significant role in the specification of business processes. To ascertain the validity of BPMN models, a disciplined approach to analyze their behavior is of particular interest to the field of business process management. This paper advocates a semantics-preserving method for transforming BPMN models into New Symbolic Model Verifier (NuSMV) language as a means to verify the models. A subset of BPMN is specified rigorously in the form of a mathematical model. With this foundation in place, the translation for the subset of BPMN notational elements is then driven by a set of formally defined rules. The practicality of our approach is exemplified using an on-line flight reservation service.
UNIFIED CONTINUUM MODELING OF FLUID-STRUCTURE INTERACTION
Authors: HOFFMAN JOHAN , JANSSON JOHAN , STÖCKLI MICHAEL
Published: March 2011

In this paper, we describe an incompressible Unified Continuum (UC) model in Euler (laboratory) coordinates with a moving mesh for tracking the fluid-structure interface as part of the discretization, allowing simple and general formulation and efficient computation. The model consists of conservation equations for mass and momentum, a phase convection equation and a Cauchy stress and phase variable θ as data for defining material properties and constitutive laws. We target realistic 3D turbulent fluid-structure interaction (FSI) applications, where we show simulation results of a flexible flag mounted in the turbulent wake behind a cube as a qualitative test of the method, and quantitative results for 2D benchmarks, leaving adaptive error control for future work. We compute piecewise linear continuous discrete solutions in space and time by a general Galerkin (G2) finite element method (FEM). We introduce and compensate for mesh motion by defining a local arbitrary Euler–Lagrange (ALE) map on each space-time slab as part of the discretization, allowing a sharp phase interface given by θ on cell facets. The Unicorn implementation is published as part of the FEniCS Free Software system for automation of computational mathematical modeling. Simulation results are given for a 2D stationary convergence test, indicating quadratic convergence of the displacement, a simple 2D Poiseuille test for verifying correct treatment of the fluid-structure interface, showing quadratic convergence to the exact drag value, an established 2D dynamic flag benchmark test, showing a good match to published reference solutions and a 3D turbulent flag test as indicated above.
ELECTRONIC PROPERTIES OF CALCIUM ULTRATHIN LAYERS ON Cu(111): A HIGH-RESOLUTION ELECTRON ENERGY LOSS SPECTROSCOPY STUDY
Authors: POLITANO ANTONIO
Published: March 2011

The electronic properties of a Ca bilayer deposited on Cu(111) have been investigated by high-resolution electron energy loss spectroscopy. For the as-deposited Ca bilayer, the surface plasmon was recorded at 3.3eV. Temperature induces a surface metal-insulator transition (evidenced by the shift of the surface plasmon energy), leading to the formation of CaO thin layers which are highly reactive towards water molecules. The presence of occupied d band in the calcium overlayer modifies surface plasmon frequency and strongly influences its dispersion relation. Results are well explained within the framework of the s-d polarization theory.
CHARACTERIZATION OF SURFACE DEFECTS THROUGH THE MODIFICATION OF THE INFRARED PROFILE OF ADMOLECULES: APPLICATION TO CO MOLECULES ADSORBED ON (100) MgO AND NaCl SURFACES
Authors: ZORGATI HANEN , SAID MONCEF , RAMSEYER CHRISTOPHE , GIRARDET CLAUDE
Published: March 2011

Real surfaces display defects originating either from thermodynamic principles or from local instabilities. In order to help and characterize these surfaces and their defects, infrared spectroscopy of physisorbed test molecules can be used. As an example, we study the behavior of the infrared response of CO molecules randomly deposited on ionic surfaces of MgO and NaCl with the concentration of dipolar defects randomly distributed on these surfaces. The vibrational peak is shifted and asymmetrically broadened when the defect concentration increases as a result of surface inhomogeneity, in semi-quantitative agreement with experimental data.
SYNTHESIS AND LUMINESCENCE PROPERTIES OF ZnO NANONEEDLE ARRAYS VIA ELECTRODEPOSITED METHOD
Authors: ZHAO SHIHUA , MA HUANFENG , WANG LINGLING , YANG LEI , CUI YUTING
Published: March 2011

ZnO nanoneedle arrays were obtained from the transformation of ZnC2O4 precipitate, which was synthesized via electrodeposited method at room temperature. The diameter of those grown ZnO nanoneedles is about 80 nm. The XRD pattern and the HRTEM image indicate that the grown ZnO nanoneedles have the preferential growth toward (101) direction. The possible growth mechanism of the ZnC2O4 nanoneedle arrays is proposed and is different from the traditional V-L-S and V-S models. The study on the PL spectrum of those ZnO nanoneedles shows the near band-edge emission band (379 nm) and the green emission band (510 nm). Especially, a red shift of the green emission band emerges with the increase of the annealing temperature and time.
ENHANCEMENT OF SUPERCONDUCTIVITY OF Pb ULTRA-THIN FILMS BY THE INTERFACE EFFECT
Authors: LI WEN-JUAN , SUN YU-JIE , ZHANG TONG , ZHU XIE-GANG , WANG GUANG , JIA JIN-FENG , MA XUCUN , CHEN XI , XUE QI-KUN
Published: March 2011

We have studied the superconductivity of Pb ultra-thin films with thickness from 1 monolayer (ML) to 7 ML grown on Si(111) by molecular beam epitaxy. In situ low temperature scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES) measurements were performed on the films. It is suggested that the interface effect plays a critical role in enhancing the electron-phonon coupling, which consequently increases the superconducting transition temperature when a film reaches to the two-dimensional limit.
SYNTHESIS AND CHARACTERIZATION OF Fe NANOWIRE ARRAYS BY AC ELECTRODEPOSITION IN PAMs
Authors: WANG XUEHUA , LI CHENGYONG , CHEN GUI , PENG CAI , HE LEI , YANG LIANG
Published: March 2011

Fe nanowire arrays were fabricated at lower voltage by alternating current (AC) electrodeposition into the highly ordered nanoholes of the porous alumina membrane (PAM) obtained by two-step anodization in oxalic acid. The morphology, structure and magnetic properties of Fe nanowire arrays were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM), respectively. The results indicate that Fe nanowires are about 50 nm in diameter which were accorded with the pores of the PAM, and stabilized in body-centered cubic (bcc) structure with a preferred orientation along (110). The easy magnetization axis is parallel to the axis of the Fe nanowires, while corresponding coercivity and squareness ratio value is 1674.5 Oe and 0.87, respectively.
In the Virtual Extension
Authors: CACM Staff
Published: March 2011

To ensure the timely publication of articles,
Communications
created the Virtual Extension (VE) to expand the page limitations of the print edition by bringing readers the same high-quality articles in an online-only format. VE articles undergo the same rigorous review process as those in the print edition and are accepted for publication on merit. The following synopses are from articles now available in their entirety to ACM members via the Digital Library.
Matters of design, part II
Authors: Hong Jason
Published: March 2011

The
Communications
Web site, http://cacm.acm.org, features more than a dozen bloggers in the BLOG@CACM community. In each issue of
Communications
, we'll publish selected posts or excerpts.

twitter

Follow us on Twitter at http://twitter.com/blogCACM

http://cacm.acm.org/blogs/blog-cacm

Jason Hong discusses how Apple creates well-designed products and what the human-computer interaction community can learn from its methods.
Engineering sensation in artificial limbs
Authors: Kroeker Kirk L.
Published: March 2011

Advancements in mobile electronics have led to several prosthetics innovations in recent years, but providing reliable touch sensations to users remains an elusive goal.
Social games, virtual goods
Authors: Greengard Samuel
Published: March 2011

The popularity of virtual goods and currencies in online gaming is changing how people think and act about money.
British computer scientists reboot
Authors: Underwood Sarah
Published: March 2011

After a year of turmoil, computer scientists at King's College London have retained their jobs, but substantial challenges lie ahead.
Managing global IT teams
Authors: Niederman Fred , Tan Felix B.
Published: March 2011

Successful global IT team managers combine general distributed team management skills enhanced with cultural sensitivity.
Building castles in the air
Authors: Ensmenger Nathan
Published: March 2011

Reflections on recruiting and training programmers during the early period of computing.
Platform wars come to social media
Authors: Cusumano Michael A.
Published: March 2011

The world can absorb more social media sites, but how many?
Coder's block
Authors: Neville-Neil George V.
Published: March 2011

What does it take to clear the blockage?
Asymmetries and shortages of the network neutrality principle
Authors: Gómez-Barroso José Luis , Feijóo Claudio
Published: March 2011

What could neutrality achieve?
A co-relational model of data for large shared data banks
Authors: Meijer Erik , Bierman Gavin
Published: March 2011

Contrary to popular belief, SQL and noSQL are really just two sides of the same coin.
Returning control to the programmer
Authors: Parri Jonathan , Shapiro Daniel , Bolic Miodrag , Groza Voicu
Published: March 2011

Exposing SIMD units within interpreted languages could simplify programs and unleash floods of untapped processor power.
Successful strategies for IPv6 rollouts.
Authors: Limoncelli Thomas A. , Cerf Vinton G.
Published: March 2011

Knowing where to begin is half the battle.
Design principles for visual communication
Authors: Agrawala Maneesh , Li Wilmot , Berthouzoz Floraine
Published: March 2011

How to identify, instantiate, and evaluate domain-specific design principles for creating more effective visualizations.
Why STM can be more than a research toy
Authors: Dragojević Aleksandar , Felber Pascal , Gramoli Vincent , Guerraoui Rachid
Published: March 2011

Despite earlier claims, Software Transactional Memory outperforms sequential code.
Liability issues in software engineering
Authors: Le Métayer Daniel , Maarek Manuel , Mazza Eduardo , Potet Marie-Laure , Frénot Stéphane , Tong Valérie Viet Triem , Craipeau Nicolas , Hardouin Ronan
Published: March 2011

This paper reports on the results of a multidisciplinary project involving lawyers and computer scientists with the aim to put forward a set of methods and tools to (1) define software liability in a precise and unambiguous way and (2) establish such liability in case of incident. The overall approach taken in the project is presented through an electronic signature case study. The case study illustrates a situation where, in order to reduce legal uncertainties, the parties wish to include in the contract specific clauses to define as precisely as possible the share of liabilities between them for the main types of failures of the system.
Q&A: The chief computer
Authors: Hoffmann Leah
Published: March 2011

Kelly Gotlieb recalls the early days of computer science in Canada.
Emergency! Web 2.0 to the rescue!
Authors: Majchrzak Ann , More Philip H. B.
Published: March 2011

Emergent serendipity fosters volunteerism driven by creative problem solving, not simply following directions.
A research doctorate for computing professionals
Authors: Grossman Fred , Tappert Charles , Bergin Joe , Merritt Susan M.
Published: March 2011

Looking back on the first decade of the Doctor of Professional Studies in Computing---an ambitious doctoral track for people who want to do research in an industrial setting.
Achievements and challenges in software reverse engineering
Authors: Canfora Gerardo , Di Penta Massimiliano , Cerulo Luigi
Published: March 2011

Deeply understanding the intricacies of software must always come before any considerations for modifying it.
Calvin's Grace Hopper birthday celebration
Authors: Adams Joel
Published: March 2011

It is a sad fact that most college students today have no idea who Grace Hopper was, or of her pioneering work in computing. The 2010
Computer Science Education Week
provided the perfect opportunity to remedy this situation at Calvin College.
Why Computer Science Ed Week?
Authors: Richardson Debra , Farmer Ruthe
Published: March 2011

Computer Science Education Week (CSEdWeek) is a call to action to raise awareness about computing careers and the critical need to elevate computer science education at all levels. The 2nd annual CSEdWeek, which took place December 5--11, 2010, was a smashing success, thanks to incredible partner support, a new website, and engagement from the computing community. About 280 CSEdWeek-related events and activities engaged students, parents, teachers and the computing community around the world.
SIGCSE by the numbers
Authors: Walker Henry M.
Published: March 2011

Since conferences are a central part of SIGCSE activities, members regularly discuss the submission and reviewing process for various conferences.
What it's like to participate in an ITiCSE working group
Authors: Adams Liz , Börstler Jürgen
Published: March 2011

Have you ever participated in a working group at ITiCSE? No? Then you have missed a great opportunity to meet and work with a group of like-minded educators on a topic of common interest. The actual meeting at ITiCSE translates to hard work, but also a lot of fun.
Confessions of a working group junkie
Authors: Riedesel Charles
Published: March 2011

For years I have attended ITiCSE in exotic locales, only to be willingly sequestered in unremarkable rooms for days, trying to hammer out optimal wording for papers under strict time constraints. Why do I do this to myself? Is it the twinges of guilt I feel for attending ACM's ICPC (International Collegiate Programming Contest) all these years, where I get to relax while watching my teams struggle against the clock with blockbuster programming problems? My answer is a resounding NO!
Computing Education Coordinating Council (CECC)
Authors: Guzdial Mark
Published: March 2011

Professional organizations in computing sometimes collaborate around education (notably in the ACM/IEEE computing curricula volumes). This is, however, too rare. We need our professional organizations to speak with a common voice on computing education issues like public policy and K-12 education to support the critical needs of our information-based world.
A fortran unit-testing framework utilizing templating and the PyF95++ toolset
Authors: List Michael , Car David
Published: March 2011

A simple unit testing framework has been developed utilizing a templating capability and Python based preprocessor for Fortran. The implementation of this framework and its use for testing serial and parallel components is discussed. The capability was successfully applied to the development of a Fortran Standard Template Library and associated toolsets.
Electrochemical Behavior of Nickel ACD-Electroless Deposition
Authors: Magagnin Luca , Cojocaru Paula , Cavallotti Pietro Luigi
Published: March 2011

Deposition of metals and other materials (oxide, polymer, salt) from aqueous solutions without an external current are described in the literature as electroless deposition. The mechanism to explain ACD-electroless deposition of nickel layers are reviewed and the fundamental characteristics of the process underlined, in comparison with the nickel electrodeposition. Results obtained with the secondary current pulse method during deposition with the ACD-electroless process are presented and show the main differences between the two processes: ACD-electroless process shows a reversible behaviour, whilst electroplating process is strongly irreversible. The results are interpreted according to the reactions prevailing at the reacting surface and strengthened by the electrochemical characterization performed in the ACD electrolyte and in sodium hypophosphite only solution.
New Surface-Activation-Process for Electroless Deposition of Adhesive Metal (Ni, Cu) Films on Si Substrates
Authors: Yae Shinji , Sakabe Keisuke , Fukumuro Naoki , Sakamoto Susumu , Matsuda Hitoshi
Published: March 2011

We report a new surface-activation process for direct electroless deposition of adhesive metal films on silicon (Si) substrates. This process, which electrolessly forms metal nanorods in Si, consists of three steps: Step 1) displacement deposition of metal nanoparticles; Step 2) metal-particle-assisted hydrofluoric acid etching for catalytic nanopore formation; and Step 3) autocatalytic electroless deposition of metal film on the Si surface. In this study, our new surface-activation process is successfully applied not only to nickel and cobalt but also to adhesive copper film deposition on Si substrates.
Activation Free Electroless Ni for High Aspect Ratio Submicron Vias for Microchip Application
Authors: Tiwari Chandra S.
Published: March 2011

Electroless (EL) processes have been explored for multiple applications in chip manufacturing over last decade. This paper presents the application of EL Ni for via fill. The inherent seam and void in traditional TiN/W processes for high-aspect-ratio vias pose reliability issues. The approach discussed in this article demonstrates that EL Ni is a feasible alternative to TiN/W for high-aspect-ratio vias. The EL Ni fill provides a void- and seam-free fill; it also presents some unique challenges.
Investigation of Dimethyl Sulfoxide Electrolytes for Electrodepositing Thermoelectric Bismuth Telluride Films
Authors: Nguyen Hai P. , Su Jiale , Wang Ziyang , Vullers Ruud J. M. , Vereecken Philippe M. , Fransaer Jan
Published: March 2011

Dimethyl sulfoxide (DMSO) electrolytes were investigated for the electrodeposition of bismuth telluride films for thermoelectric applications. The investigation revealed the influences of electrolyte ion concentration, deposition potential, and temperature on the alloy composition. Full composition range of bismuth telluride BixTey materials could be prepared by varying either electrolyte ion concentration or deposition potential. The film morphology was found smooth at the stoichiometric composition and affected by the film composition, rather than deposition conditions. The highest Seebeck coefficient observed for n-type films was -134 uV/K (unannealed) and +150 uV/K for p-type (annealed).
Electrodeposition of Semiconductor n-CdTe and p-CdTe in Aqueous Medium and Aluminum Metal in a Nonaqueous Medium
Authors: Ashead Brian , Khan Shahed U.
Published: March 2011

Both n-type and p-type semiconductor CdTe were synthesized by electrodeposition from an aqueous deposition bath. Electrodeposition potential was found to be the key factor to synthesize the CdTe semiconductor of any specific conductivity type. The electrodeposition potentials of -0.4 V and 0.4 V versus Ag/AgCl generated the p-type and n-type CdTe respectively. The optimum deposition time was found to be 90 minutes for the best photoresponce of CdTe during water-splitting reaction. The indirect band gap energy of CdTe was found tunable from 1.55 to 2.00 eV by controlling both electrodeposition potential and the annealing time. Crystalline aluminum metal was deposited on a platinum electrode tip at room temperature in a non-aqueous deposition bath of anhydrous toluene containing aluminum bromide and the supporting electrolyte, tetra butyle ammonium bromide. Anhydrous condition was found to be the critical factor for the success of electrodeposition and production of aluminum metal at room temperature in a non-aqueous deposition bath.
Cationic and Anionic Transport through Single Quartz Nanopipettes
Authors: Brown Warren , Kvetny Maksim , Liu Juan , Wang Gangli
Published: March 2011

Ionic transport through single quartz nanopipettes is studied by cyclic voltammetry and multi-frequency impedance spectroscopy. DC current rectification is correlated to the features in the two dimensional impedance Nyquist plots, by varying the ionic strength tailored by solution electrolyte concentration. Normalized conductivity is relatively comparable in different electrolyte concentrations at negative potentials, but is drastically enhanced at lower concentration at positive bias potentials. By employing electrolytes with common anions but different cations, the respective contribution of cation and anion transport to the overall ionic current is qualitatively differentiated. The phenomena are attributed to the fixed charges at the substrate-solution interface. Interestingly, the amount of fixed interfacial charges, or surface charge density at the mass transport limiting region, was found to develop over time, which results in more significant current rectification.
(Invited) Remembering Ulrich Gösele
Authors: Föll Helmut
Published: March 2011

Prof. Dr. Ulrich M. Gösele died unexpectedly and far too early in Nov. 2009. He would certainly have participated in several ses-sions of this meeting; his untimely death deprived us of that pleasure. Prof. Ulrich Gösele was an outstanding scientist with a distinguished record in many fields, including porous semicon-ductor science and technology. In this contribution for "Pits and Pores" a personal account of his life is given, based not only on scientific collaboration but also on a longstanding friendship. He will be remembered not only for his outstanding contributions to science but also as a reliable and witty friend and a highly motivating mentor.
Silicon Nanowire Arrays Combining Nanosphere Lithography and Metal-Assisted Etching
Authors: Lévy-Clément Claude , Wang Xiaodong , Pittet Patrick
Published: March 2011

Arrays of vertically aligned Silicon nanowires (SiNWs) were obtained using a top-down multistep method that combined nanosphere lithography and metal-assisted etching of bulk Si. This combined technique is a very simple and fast preparation method, which enables the formation of large-scale arrays with long-range periodicity of vertically standing nanorods/nanowires with well-controlled diameter, length and density. After deposition of a monolayer of polystyrene (PS) spheres with a diameter of 200 or 100 nm, on a Si wafer, they were subjected to a reactive ion etching treatment in oxidizing atmosphere. The PS spheres were used as a mask to deposit a thin layer of gold (Au) on Si, between the spheres. The etching occurring preferentially at the interface between Au and Si, the Si surface protected by the spheres was not dissolved resulting in free standing SiNWs. Progress made in the development of the multistep method was reported, enabling the formation of SiNWs with uniform diameter as small as 60 nm.
(Invited) Rational Design of Etchants for Electroless Porous Silicon Formation
Authors: Kolasinski Kurt W. , Gogola Jacob W.
Published: March 2011

From fundamental considerations of the surface chemistry of Si etching in fluoride solutions as well as pore formation and propagation, we develop a mechanistic understanding of what must be known for rational development of etchants: (1) an acidic fluoride solution because the presence of OH- promotes step flow etching, (2) sufficiently high fluoride concentration compared to the oxidant concentration, (3) the oxidant must be able to inject holes into the Si valance band at a sufficient rate, hence E° > ~0.7 V is required, (4) oxide formation needs to be slow or nonexistent so as to avoid the formation of a uniform oxide and associated electropolishing, (5) reduction of the oxidant must lead to soluble products, (6) film homogeneity is enhanced if the oxidant's half-reaction does not evolve gas, and finally (7) the net etching reaction has to be sufficiently anisotropic to support pore nucleation and propagation.
Ellipsometry, Reflectometry, and XPS Comparative Studies of Oxidation Effects on Graded Porous Silicon Antireflection Coatings
Authors: Selj Josefine H. , Tho̸gersen Annett , Stensrud Marstein Erik
Published: March 2011

Efficient antireflection coatings (ARC) improve the light collection and thereby increase the current output of solar cells. By simple electrochemical etching of the Si wafer, porous silicon (PS) layers with excellent broadband antireflective properties can be fabricated. The close relation between porosity and refractive index, modeled using the Bruggeman effective medium approximation, allows PS multilayers to be tailored to fabricate ARCs optimized for use in solar cells. In this work, the effect of ageing on the reflection properties of multilayered PS ARCs is studied. The reflection is correlated to the oxidation of the structures through the use of x-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE). It is found that even after extensive oxidation, very small changes in reflectivity are measured.
A Correlation between the Kinetics and Thermodynamics for the Photo-Electrochemical Etching of N-Si in 2MHF-Ethanolic Solutions
Authors: Jehng Wern-Dare , Lin Jing-Chie
Published: March 2011

In the photo-electrochemical etching of Si/HF system, the kinetics was investigated extensively in the literature. Usually, any problem belonging to science and engineering was solved using both thermodynamic and kinetic aspects. In this work, the kinetic of the system was correlated with the thermodynamics, by introducing the energy bend diagrams, to comprehend the etching trend. The effect of ethanol added into the system was concerned. The results from photo-electrochemical kinetics (i.e., i-v diagram) are in agreement with that expected from thermodynamics via estimation of activation energy estimation from the corresponding energy band diagrams. The SEM morphology reconfirmed the result inferred from both aspects.
Area Selective Formation of Porous Type Aluminum Anodic Oxide Film by a Solution Flow-Type Micro Droplet Cell
Authors: Murata Takuya , Goto Yoshihito , Sakairi Masatoshi , Fushimi Koji , Kikuchi Tatsuya
Published: March 2011

A novel solution flow-type micro droplet cell with co-axial dual capillary tubes (Sf-MDC) was applied to form porous type aluminum anodic oxide film locally. This technique makes it possible to form porous type anodic oxide film on aluminum locally. When the droplet cell remains stationary, the oxide film was growing both vertically and laterally. The growth rate in the lateral direction can be controlled by moving the droplet cell. By moving the droplet cell, a porous type anodic oxide film line was successfully formed. The thickness of the oxide film increases with decreasing scanning speed of the cell. The oxide film growth rate was greatly affected by specimen temperature.
Nanoimprinting Process Using Highly Ordered Anodic Porous Alumina
Authors: Yanagishita Takashi , Nishio Kazuyuki , Masuda Hideki
Published: March 2011

An anodic porous alumina with precisely controlled size and depth of holes was prepared and used for nanoimprinting of a polymer. As a typical application of nanoimprinting, antireflection (AR) structures of polymer were prepared. The obtained AR structure with optimized geometrical structures exhibited a low reflectance of less than 0.2 %. The present process allows the high throughput production of polymer AR structures with large sizes.
Pt Filling within Mesoporous Silicon by Electrodeposition
Authors: Fukami Kazuhiro , Shiojima Daichi , Sakka Tetsuo , Ogata Yukio H.
Published: March 2011

The filling of platinum within mesoporous silicon prepared in highly doped p-type silicon was investigated. The deposition of platinum within the mesopores was achieved when using a solution with Pt (II), while the pores were kept empty in a solution with Pt (IV). The particles of platinum were obtained by displacement deposition. The particles were distributed uniformly within the mesopores. The electrodeposition under a weak cathodic polarization resulted in the formation of platinum rods due to the continuous filling from the bottom. The displacement deposition was successfully suppressed by modifying the pore wall by an organic group. The amount of platinum deposition obtained under the cathodic polarization was significantly decreased when using the wall-modified mesoporous silicon. These results suggest that the electrodeposition and displacement deposition occur simultaneously within as-prepared mesoporous silicon.
A Porous Silicon/Iron Oxide Nanocomposite with Superparamagnetic and Ferromagnetic Behavior
Authors: Granitzer Petra , Rumpf Klemens , Venkatesan Munuswamy , Cabrera Lourisa , Roca Alejandro , Morales M. Puerto , Poelt Peter , Albu Mihaela
Published: March 2011

The infiltration of iron oxide nanoparticles into mesoporous silicon is performed to investigate the influence of different arrangements of the particles on the magnetic behaviour of the achieved nanocomposite consisting of a semiconductor and a magnetic material. The porous silicon is fabricated from a highly doped n-type silicon wafer by anodization. The Fe3O4 particles fabricated by high temperature decomposition offer a size of 5 and 8 nm, respectively. In the present work the influence of the porous silicon matrix on the magnetic behaviour of such hybrid materials is figured out. In general iron oxide particles of a few nanometer in size are superparamagnetic but due to dipolar coupling between them the blocking temperature can be shifted, which is demonstrated by modification of the particle size and the distance between the particles.
Nano-Branched Gold Deposits Prepared by Electrochemical Deposition Using Porous Silicon
Authors: Miyagawa Ryohei , Fukami Kazuhiro , Chourou Mohamed L. , Sakka Tetsuo , Ogata Yukio H.
Published: March 2011

As an SERS-active template, Au deposited mesoporous silicon and nano-branched Au rod array was prepared by anodization of Si in hydrofluoric acid solutions, followed by the displacement deposition of Au in solution containing AuCl4− or by the electrodeposition in solution containing Au(S2O3)(SO3)25−. The SERS-activity measured with 4-4' bipyridine as the target molecule was strongly affected by the morphology of Au structures.
Gold Electrodeposition into Mesoporous Silicon: The Effect of Solution Composition
Authors: Chourou Mohamed L. , Fukami Kazuhiro , Miyagawa Ryohei , Sakka Tetsuo , Ogata Yukio H.
Published: March 2011

Electrodeposition of Au in mesoporous Si prepared in a highly doped p-type Si was investigated. When the Au electrodeposition was carried out using the complex Au(S2O3)23-, the mesopores with 5 µm depth were filled with Au continuously from the bottom to the opening. When the Au electrodeposition was carried out using the complex AuCl4-, the openings of the mesopores were covered with an Au film. The solution composition has a strong influence on the electrodeposition behavior. The effect of the displacement deposition occurring at the initial few seconds before conducting the Au electrodeposition seems to be a key factor for the difference. The different behaviors of the electrodeposition with different supporting electrolytes were compared and discussed.
Porous Silicon as a Nanostructured Template for Enhanced Immobilization and Crystallization of Inorganic and Biomaterials
Authors: Stolyarova Sara , Nemirovsky Yael
Published: March 2011

In the current paper, we review our experimental and theoretical results demonstrating enhanced immobilization and crystallization of inorganic and biological materials on porous silicon and present additional explanation of observed effects. The examples of experimental results on room-temperature crystallization of SiO2 as well as of enhanced adhesion and crystallization of ceramic sol-gel derived films on porous silicon are shown. These phenomena have been observed at conditions which were insufficient for crystallization on flat silicon surfaces. The facilitation of crystallization on porous silicon is explained by surface fractality as well as by the decrease of potential barrier of nucleation related to the decrease of the critical nucleus volume at heterogeneous nucleation in pores.
Optical Properties of Germanium Dots Self-Assembled on Porous TiO2 Templates
Authors: Lockwood D. J. , Rowell N.L. , Berbezier I. , Amiard G. , Favre L. , Ronda A. , Faustini M. , Grosso D.
Published: March 2011

Self-assembled Ge quantum dots were formed by in-situ thermal annealing of a thin amorphous Ge layer deposited by molecular beam epitaxy on a thin porous TiO2 layer grown on SiO2 on Si(001). For samples with dot diameters ranging from 10 to 35 nm, the dot photoluminescence (PL) appeared primarily as a wide near-infrared band peaked near 800 meV. The peak energy of the PL band reflects the average dot size and its shape depends on the dot size distribution. Using a tight binding bandgap model, we have analyzed the PL spectrum in terms of the dot size distribution. The observed size distribution determined from transmission electron and atomic force microscopy allowed the determination of the nonlinear increase in the PL efficiency with decreasing dot diameter. Knowing this generic PL efficiency, we show that it is possible to evaluate the size distribution of Ge dots from their PL energy dependence.
Nanostructure Directed Gas-Surface Physisorption Based on Selective Modification of Nanopore Coated Micropores
Authors: Gole James L. , Ozdemir Serdar
Published: March 2011

Rapidly responding, reversible, sensitive, and selective gas sensors are formed with a highly efficient electrical contact to a nanopore covered micropore array. Significant changes are created with selective nanostructure deposition, based on a novel acid-base concept and correlating with a basis in "directed" physisorption. Highly selective surface coatings on 'phase matched' silicon nanopores placed on porous silicon micropores facilitate the application of nanostructured metal oxide fractional surface depositions, and provide for higher sensitivities and selectivity. Nanostructure depositions, which include AuxO, SnO2, CuxO, and NiO, as well as nano-alumina, and titania provide for the detection of gases including NO, NO2, CO, NH3, PH3, SO2, H2S, HCl, and toluene in an array-based format at the sub-ppm level. Detection is dependent on [1] the nature of the combined pore structure (hybrid), [2] the generation of low-resistance contacts to this structure, and [3] the positioning of select nanostructures onto the structure.
Pd Assisted HF Etching of Si: Electrochemical Measurement
Authors: Tashiro Masayuki , Yae Shinji , Morii Yuma , Fukumuro Naoki , Matsuda Hitoshi
Published: March 2011

Metal-assisted HF etching of Si has attracted considerable attention as a new electroless method that can produce porous Si by immersing metal-modified Si in a HF solution without bias. Such etching generally uses not only metal-modified Si but also an oxidizing agent. Palladium exhibits high activity in assisted etching under dissolved-oxygen-free and dark conditions. In this study, we investigate the Pd assisted HF etching of n-Si by electrochemical measurements. The potential of Pd metal on Si is more negative than the potential of hydrogen evolution at open circuit conditions. Anodic current generation of Pd-modified Si electrodes at positive bias and the localization of etching under Pd films at low thickness indicate that Pd catalyzes the anodic dissolution of Si and the cathodic hydrogen evolution.
Thin Porous Silicon Films Displaying a Near-Surface Dip in Porosity
Authors: Selj Josefine H. , Tho̸gersen Annett , Bergstrom Paul , Foss Sean Erik , Stensrud Marstein Erik
Published: March 2011

Studies of the depth profile of Porous Silicon (PS) structures etched under a wide span of different formation parameters have been performed using Spectroscopic Ellipsometry (SE) and Transmission Electron Microscopy (TEM). Incorporation of a sharp dip in the porosity profiles close to the sample surface was required for several types of PS films in order to successfully fit ellipsometric data to a Bruggeman Effective Medium Model (BEMA). TEM studies show a corresponding lower porosity region near the sample surface. Investigations have been performed in order to understand the origin of this dip and to explore the parameter space where it is detected. The detected low porosity region is discussed in the context of current knowledge on pore nucleation and growth mechanisms of PS.
Production and Investigation of Porous Si-Ge Structures for Thermoelectric Application
Authors: Cojocaru Ala , Carstensen Juergen , De Boor Johannes , Kim Dong Sin , Schmidt Volker , Föll Helmut
Published: March 2011

Mesoporous Si and Si-Ge are promising candidates for efficient thermoelectric converters needed for energy harvesting, e.g. from hot exhaust pipes of cars. Suitable mesoporous structures must meet a number of requirements concerning their geometry and processing costs, and suitable pore etching techniques have been developed. The paper addresses these issues, including the use of Si-Ge substrates from specially grown Si-Ge crystals. It is shown that most geometric and process requirements can be met by etching so-called current line pores under special conditions. First results concerning thermal and electrical properties are also presented.
Nanotubes Consisting of Ni-Particles Covering the Walls of Porous Silicon
Authors: Rumpf Klemens , Granitzer Petra , Poelt Peter , Albu Mihaela , Ali Kamran , Reissner Michael
Published: March 2011

Ni-nanostructures are electrochemically deposited within the pores of mesoporous silicon. The porous silicon template is fabricated with straight and separated pores. The geometry of the metal deposits can be tuned in a wide size range between 50 nm and a few micrometers and thus specimens with specific magnetic properties can be achieved. Furthermore small Ni-particles between 3 and 6 nm in size can be precipitated on the pore walls with various distances. In the case of a closely packed distribution the particle arrangement results in metal tubes which cover the pore walls. The superparamagnetic Ni-particles forming such a tube are magnetically interacting which leads to a ferromagnetic behavior of the system.
Corrosion Inhibition of 304 Stainless Steel, Copper and Nickel Metals Using Mesoporous Silicate (MCM- 41) and 2, 5-Distyrylpyrazine Photopolymer
Authors: Zakaria Mohamed B. , Elmorsi Mohamed A. , Ebied El-Zeiny M.
Published: March 2011

Mesoporous silicate (MCM-41) and 2, 5-distyrylpyrazine photo- polymer (poly-DSP) were used as corrosion protective coatings for 304 stainless steel, copper and nickel metals. Films on metal surfaces were prepared by dip-coating and vapor deposition (CVD, PVD) methods. Poly-DSP thin films formed by vapor deposition are expected to be incorporated through pores and micro-cracks of SiO2 thin film resulting in extra corrosion protection upon photo polymerization. MCM-41 thin films were characterized by x-ray diffraction (XRD), infrared (IR), BET and electron microscopy (SEM, TEM) techniques. Corrosion protection was studied in 2M HCl aqueous solutions using weight loss and potentiodynamic polarization techniques. The temperature effect on corrosion rates was also studied and the thermodynamic activation parameters of the corrosion reaction were determined. Different corrosion parameters were evaluated including, corrosion current density, corrosion potential, corrosion rate and Tafel constants. The calculated percentage of inhibition efficiencies of the coated electrodes reaches ca 93% in some cases
Natural Resource Limitations to Terawatt Solar Cell Deployment
Authors: Tao Coby , Jiang Jiechao , Tao M.
Published: March 2011

The predicted energy demands will reach 28 terawatts by 2050 and 46 terawatts by 2100. The deployment of solar cells as a source of energy will have to expand to a scale of tens of peak terawatts in order to become a noticeable source of energy in the future. Of the current commercial and developmental solar cell technologies, the majority have natural resource limitations that prevent them from reaching a terawatt scale. These limitations include high energy input for crystalline-Si cells, limited material production for GaAs cells, and material scarcity for CdTe, CIGS, dye-sensitized, crystalline-Si, and amorphous Si cells. In this paper, we examine these resource limitations under the best scenarios, i.e. the maximum possible power from each of these solar cell technologies. Without significant technological breakthroughs, these technologies combined would meet only 1 - 2% of our energy demands in 2100.
Yttrium-Doped Zinc Oxide as a Terawatt-Scale Transparent Conducting Oxide
Authors: Tao M. , Han Xiaofei
Published: March 2011

The desirable features of an ideal transparent conducting oxide for terawatt-scale solar cells include abundant raw materials, low cost, high performance, and low process temperature. In this paper we examine all the Group IIIA and IIIB elements as potential n-type dopants for ZnO and suggest yttrium as an ideal dopant for this purpose. Experimental results on electrodeposited yttrium-doped ZnO are presented. The lowest resistivity in yttrium-doped ZnO is 6.3E-5 Ohm-cm, while the average resistivity is ~2E-4 Ohm-cm. The maximum process temperature is 300°. The transmittance of yttrium-doped ZnO is ~80%. Thermal stability of yttrium-doped ZnO is also investigated. It has a real chance to become an industry standard transparent conducting oxide for terawatt-scale solar cells, as its performance is comparable to indium tin oxide, its deposition is solution-based, and yttrium is abundant.
Crack Propagation in Large Diameter PV Silicon
Authors: Kulshreshtha Prashant K. , Witting Ian T. , Youssef Khaled , Good Ethan , Rozgonyi George
Published: March 2011

We report on crack propagation in CZ silicon wafers grown for photovoltaic (PV) applications at faster growth rates than those typical for 200 mm diameter ingots. Enhanced thermal gradients and point defect/impurity distributions associated with rapid growth produces large localized stresses in the wafer core which impacts the direction of propagating cracks. The stress modified crack behavior deviates considerably from the energetically favorable Si[110]/(111) systems enabling scenarios that behave like a ductile fracture following a radial path. Minority carrier lifetime mapping and microscopic etch pit measurements confirmed the presence of a series of radial oxygen precipitate (OP) rings, which impact the energy transfer process at the expanding crack-tip, thereby modifying the crack stress path. Raman spectroscopy was used to quantify the local stresses due to radial oxygen precipitate variations, whereas TEM studies confirmed the presence of OP's, their influence on defect generation and probable role on crack path deviation.
Mono-Crystalline Silicon Solar Cell Optimization and Modeling
Authors: Huang Joanne , Moroz Victor
Published: March 2011

The optimization of a mono-crystalline silicon solar cell is complicated due to various competing physical mechanisms that determine its performance. In this paper a three-dimensional (3D) electrical simulation template for mono-crystalline silicon solar cell optimization is developed using Synopsys Sentaurus tool suite, and is used to demonstrate an optimization space of over 1 percent in terms of cell power conversion efficiency. The key design parameters include rear point contact area coverage, substrate doping concentration, cell thickness, and the junction. Comparison between three-dimensional analysis and the simplified two-dimensional and one-dimensional cases is also provided.
Electrochemical Etching of Zinc Oxide for Silicon Thin Film Solar Cell Applications
Authors: Pust Sascha E. , Worbs Janine , Hüpkes Juergen , Klemm Sebastian O. , Mayrhofer Karl J.
Published: March 2011

A novel approach is presented for introducing a surface morphology with beneficial light scattering properties to sputter-deposited ZnO:Al films, being used as front contact in Si thin film photovoltaic devices. Electrochemical anodization was used to trigger local corrosion, leading to interfacial structures complementary to those commonly prepared by an etching step in diluted HCl. By systematic variation of electrochemical etching conditions and electrolytes, sensible experimental parameters were evaluated for the preparation of ZnO films that can be applied in Si thin film solar cells. The prepared films were characterized by scanning electron microscopy, four-point resistance and Hall measurements. Furthermore, the kinetics of the heterogeneous interfacial reaction during the corrosion process were studied utilizing electroanalytical techniques. This allowed the identification of the processes occurring at the solid/liquid interface. Application of such films in microcrystalline Si single junction solar cells has shown promising initial results.
Recovery of Light Induced Degradation of Micromorph Solar Cells by Reverse Bias
Authors: Sun Hung-Chang , Chen Wei-Di , Cheng Tzu-Huan , Yang Ying-Jhe , Liu C. W. , Shih Hung-Tao
Published: March 2011

The recovery of light induced degradation of the micromorph solar cells is investigated by applying reverse bias for the first time. The illuminated current density-voltage (J-V) characteristics and external quantum efficiency (EQE) show that the degraded efficiency can be recovered by applying reverse bias. The efficiency recovered ratio increases with the field strength, and the efficiency has higher recovery rate under more intense illumination intensity