WorldWideScience

Sample records for devices film badge

  1. Measurement error in longitudinal film badge data

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, J.L

    2002-04-01

    The classical measurement error model is that of a simple linear regression with unobservable variables. Information about the covariates is available only through error-prone measurements, usually with an additive structure. Ignoring errors has been shown to result in biased regression coefficients, reduced power of hypothesis tests and increased variability of parameter estimates. Radiation is known to be a causal factor for certain types of leukaemia. This link is mainly substantiated by the Atomic Bomb Survivor study, the Ankylosing Spondylitis Patients study, and studies of various other patients irradiated for therapeutic purposes. The carcinogenic relationship is believed to be a linear or quadratic function of dose but the risk estimates differ widely for the different studies. Previous cohort studies of the Sellafield workforce have used the cumulative annual exposure data for their risk estimates. The current 1:4 matched case-control study also uses the individual worker's film badge data, the majority of which has been unavailable in computerised form. The results from the 1:4 matched (on dates of birth and employment, sex and industrial status) case-control study are compared and contrasted with those for a 1:4 nested (within the worker cohort and matched on the same factors) case-control study using annual doses. The data consist of 186 cases and 744 controls from the work forces of four BNFL sites: Springfields, Sellafield, Capenhurst and Chapelcross. Initial logistic regressions turned up some surprising contradictory results which led to a re-sampling of Sellafield mortality controls without the date of employment matching factor. It is suggested that over matching is the cause of the contradictory results. Comparisons of the two measurements of radiation exposure suggest a strongly linear relationship with non-Normal errors. A method has been developed using the technique of Regression Calibration to deal with these in a case-control study

  2. Effect of environmental factors on film badge dosimetry readings of dental office personnel

    Energy Technology Data Exchange (ETDEWEB)

    Collett, W.K.; Kaugars, G.E.; Broga, D.W. (Univ. of Florida, Gainesville (USA))

    1990-12-01

    Inadvertent exposure of film badges to environmental factors may produce fogging of the film and yield higher radiation exposure readings. Common environmental factors in everyday living were studied to assess their effect on film badge readings. Only heat appeared to have any significant effect, because moisture, chemicals, pressure, cold temperature, and non-work-related electromagnetic radiation did not substantially alter film badge readings. Therefore not all unexplained high readings on personnel film badge reports may be due to heat or other common environmental factors evaluated in this study.

  3. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  4. Digital Badges in Education

    Science.gov (United States)

    Gibson, David; Ostashewski, Nathaniel; Flintoff, Kim; Grant, Sheryl; Knight, Erin

    2015-01-01

    Digital badges provide new affordances for online educational activities and experiences. When used with points and leaderboards, a badge can become a gamification element allowing learners to compete with themselves or others, and to know how close they are to accomplishing a goal and acquiring its accompanying reputation. In this role, badges…

  5. Badge Office Process Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Haurykiewicz, John Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dinehart, Timothy Grant [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parker, Robert Young [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-12

    The purpose of this process analysis was to analyze the Badge Offices’ current processes from a systems perspective and consider ways of pursuing objectives set forth by SEC-PS, namely increased customer flow (throughput) and reduced customer wait times. Information for the analysis was gathered for the project primarily through Badge Office Subject Matter Experts (SMEs), and in-person observation of prevailing processes. Using the information gathered, a process simulation model was constructed to represent current operations and allow assessment of potential process changes relative to factors mentioned previously. The overall purpose of the analysis was to provide SEC-PS management with information and recommendations to serve as a basis for additional focused study and areas for potential process improvements in the future.

  6. IDENTIFICATION BADGE WITH DETACHABLE CLIP

    Science.gov (United States)

    Burns, M.T.

    1962-09-18

    The clip has a long slot with a round enlarged end, flat on one side. The badge has a headed member that is circular except for a flat side. The badge is connected to, or disconnected from, the clip by insertion of the headed member through the enlarged end of the slot in the clip. The badge is unlikely to be accidentally disconnected from the clip while being worn on a worker's clothing, because the weight of the badge keeps the headed member away from the enlarged end of the slot in the clip, and the headed member can pass through the enlarged end of the slot only at one relative angular position between badge and clip, namely, that angle at which the flat side of the headed member is coincident with the flat side of the enlarged end of the slot. (AEC)

  7. Open Badges for Education: What Are the Implications at the Intersection of Open Systems and Badging?

    Science.gov (United States)

    Ahn, June; Pellicone, Anthony; Butler, Brian S.

    2014-01-01

    Badges have garnered great interest among scholars of digital media and learning. In addition, widespread initiatives such as Mozilla's Open Badge Framework expand the potential of badging into the realm of open education. In this paper, we explicate the concept of open badges. We highlight some of the ways that researchers have examined…

  8. Career/College Readiness: Digital Badges

    Science.gov (United States)

    Waters, John K.

    2013-01-01

    March was a big month in the world of digital badging. The MacArthur Foundation showcased winners of its Badges of Lifelong Learning competition at the Digital Media and Learning Conference in Chicago--one year after awarding those winners $2 million worth of development grants. The city of Chicago itself announced that badging would be a key…

  9. INVESTIGATION OF PHOTOELECTROCHROMIC THIN FILM AND DEVICE

    Institute of Scientific and Technical Information of China (English)

    M.J. Chen; H. Shen

    2005-01-01

    Photoelectrochromic device is a combination of dye-sensitized solar cells and electrochromic WO3 layers. Ectrochroelmic WO3 layer and TiO2 layer had been prepared by the sol-gel process, then be assembled to pohotoelectrochromic device. The effects of heating temperature on photoelectrochromic were investigated. The results showed that thin films prepared by dip-coating and spin-coating had good film quality and the device made by the method mentioned in the paper had good photoelectrochromie properties.

  10. Infrared control coating of thin film devices

    Science.gov (United States)

    Berland, Brian Spencer; Stowell, Jr., Michael Wayne; Hollingsworth, Russell

    2017-02-28

    Systems and methods for creating an infrared-control coated thin film device with certain visible light transmittance and infrared reflectance properties are disclosed. The device may be made using various techniques including physical vapor deposition, chemical vapor deposition, thermal evaporation, pulsed laser deposition, sputter deposition, and sol-gel processes. In particular, a pulsed energy microwave plasma enhanced chemical vapor deposition process may be used. Production of the device may occur at speeds greater than 50 Angstroms/second and temperatures lower than 200.degree. C.

  11. Infrared control coating of thin film devices

    Energy Technology Data Exchange (ETDEWEB)

    Berland, Brian Spencer; Stowell, Jr., Michael Wayne; Hollingsworth, Russell

    2017-02-28

    Systems and methods for creating an infrared-control coated thin film device with certain visible light transmittance and infrared reflectance properties are disclosed. The device may be made using various techniques including physical vapor deposition, chemical vapor deposition, thermal evaporation, pulsed laser deposition, sputter deposition, and sol-gel processes. In particular, a pulsed energy microwave plasma enhanced chemical vapor deposition process may be used. Production of the device may occur at speeds greater than 50 Angstroms/second and temperatures lower than 200.degree. C.

  12. Using badges to motivate and engage students

    DEFF Research Database (Denmark)

    Christensen, Inger-Marie F.; Hansen, Pernille Stenkil

    The gap between educational institutions and students is widening. Many institutions maintain traditional methods and adopt new at a slow pace. Some educators and developers are looking to gamification to bridge the gap. This workshop will help participants’ explore the potential of badges...... in education. An introduction to badges and the purposes of using these in education will be provided. Ways of integrating badges into courses will be explained. Furthermore, the process of designing and issuing badges in Blackboard Learn will be demonstrated. Participants will get the opportunity to discuss...

  13. Quantum device prospects of superconducting nanodiamond films

    Science.gov (United States)

    Mtsuko, D.; Churochkin, D.; Bhattacharyya, S.

    2016-02-01

    Nanostructured semiconducting carbon system, described by as a superlattice-like structure demonstrated its potential in switching device applications based on the quantum tunneling through the insulating carbon layer. This switching property can be enhanced further with the association of Josephson's tunneling between two superconducting carbon (diamond) grains separated by a very thin layer of carbon which holds the structure of the film firmly. The superconducting nanodiamond heterostructures form qubits which can lead to the development of quantum computers provided the effect of disorder present in these structure can be firmly understood. Presently we concentrate on electrical transport properties of heavily boron-doped nanocrystalline diamond films around the superconducting transition temperature measured as a function of magnetic fields and the applied bias current. Microstructure of these films is described by a two dimensional superlattice system which can also contain paramagnetic impurities. We report observation of anomalous negative Hall resistance in these films close to the superconductor-insulator-normal phase transition in the resistance versus temperature plots at low bias currents at zero and low magnetic field. The negative Hall effect is found to be suppressed as the bias current increase. Magnetoresistance study shows a distinct peak at zero field when measured in the low current regimes which suggest a superconductor-insulator-superconductor structure of films. Current vs. voltage characteristics show signature of π-Josephson like behaviour which can give rise to a characteristic frequency of several hundred of gigahertz. Signature of spin flipping also shows novel spintronic device applications.

  14. Additives to silane for thin film silicon photovoltaic devices

    Science.gov (United States)

    Hurley, Patrick Timothy; Ridgeway, Robert Gordon; Hutchison, Katherine Anne; Langan, John Giles

    2013-09-17

    Chemical additives are used to increase the rate of deposition for the amorphous silicon film (.alpha.Si:H) and/or the microcrystalline silicon film (.mu.CSi:H). The electrical current is improved to generate solar grade films as photoconductive films used in the manufacturing of Thin Film based Photovoltaic (TFPV) devices.

  15. 49 CFR 230.46 - Badge plates.

    Science.gov (United States)

    2010-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Gauges § 230.46 Badge plates. A metal badge plate showing the allowed steam pressure shall be attached to the boiler backhead in the cab. If boiler backhead is lagged, the lagging and jacket shall be cut away...

  16. Process compilation methods for thin film devices

    Science.gov (United States)

    Zaman, Mohammed Hasanuz

    This doctoral thesis presents the development of a systematic method of automatic generation of fabrication processes (or process flows) for thin film devices starting from schematics of the device structures. This new top-down design methodology combines formal mathematical flow construction methods with a set of library-specific available resources to generate flows compatible with a particular laboratory. Because this methodology combines laboratory resource libraries with a logical description of thin film device structure and generates a set of sequential fabrication processing instructions, this procedure is referred to as process compilation, in analogy to the procedure used for compilation of computer programs. Basically, the method developed uses a partially ordered set (poset) representation of the final device structure which describes the order between its various components expressed in the form of a directed graph. Each of these components are essentially fabricated "one at a time" in a sequential fashion. If the directed graph is acyclic, the sequence in which these components are fabricated is determined from the poset linear extensions, and the component sequence is finally expanded into the corresponding process flow. This graph-theoretic process flow construction method is powerful enough to formally prove the existence and multiplicity of flows thus creating a design space {cal D} suitable for optimization. The cardinality Vert{cal D}Vert for a device with N components can be large with a worst case Vert{cal D}Vert≤(N-1)! yielding in general a combinatorial explosion of solutions. The number of solutions is hence controlled through a-priori estimates of Vert{cal D}Vert and condensation (i.e., reduction) of the device component graph. The mathematical method has been implemented in a set of algorithms that are parts of the software tool MISTIC (Michigan Synthesis Tools for Integrated Circuits). MISTIC is a planar process compiler that generates

  17. Polycrystalline thin film materials and devices

    Energy Technology Data Exchange (ETDEWEB)

    Baron, B.N.; Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E. (Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion)

    1992-10-01

    Results of Phase II of a research program on polycrystalline thin film heterojunction solar cells are presented. Relations between processing, materials properties and device performance were studied. The analysis of these solar cells explains how minority carrier recombination at the interface and at grain boundaries can be reduced by doping of windows and absorber layers, such as in high efficiency CdTe and CuInSe{sub 2} based solar cells. The additional geometric dimension introduced by the polycrystallinity must be taken into consideration. The solar cells are limited by the diode current, caused by recombination in the space charge region. J-V characteristics of CuInSe{sub 2}/(CdZn)S cells were analyzed. Current-voltage and spectral response measurements were also made on high efficiency CdTe/CdS thin film solar cells prepared by vacuum evaporation. Cu-In bilayers were reacted with Se and H{sub 2}Se gas to form CuInSe{sub 2} films; the reaction pathways and the precursor were studied. Several approaches to fabrication of these thin film solar cells in a superstrate configuration were explored. A self-consistent picture of the effects of processing on the evolution of CdTe cells was developed.

  18. Open badges for education: what are the implications at the intersection of open systems and badging?

    Directory of Open Access Journals (Sweden)

    June Ahn

    2014-08-01

    Full Text Available Badges have garnered great interest among scholars of digital media and learning. In addition, widespread initiatives such as Mozilla’s Open Badge Framework expand the potential of badging into the realm of open education. In this paper, we explicate the concept of open badges. We highlight some of the ways that researchers have examined badges as part of educational practice and also highlight the different definitions of open-ness that are employed in popular and scholarly thought. By considering badges from three different perspectives (motivation, pedagogy, and credential and the concept of openness from three different perspectives (production, access and appropriation we develop a framework to consider the tensions where these competing conceptions meet. This explication illuminates how the ideas of open and badges intersect, and clarifies situations where these concepts come into direct conflict or mutually enhance each other. Our analysis pinpoints and elucidates particular areas where research is needed to better understand the complex phenomenon of open badges, and also offers design considerations for developers, educators, and organizations that are actively involved in open badges.

  19. Inorganic and Organic Solution-Processed Thin Film Devices

    Institute of Scientific and Technical Information of China (English)

    Morteza Eslamian

    2017-01-01

    Thin films and thin film devices have a ubiquitous presence in numerous conventional and emerging tech-nologies. This is because of the recent advances in nanotechnology, the development of functional and smart materials, conducting polymers, molecular semiconductors, carbon nanotubes, and graphene, and the employment of unique prop-erties of thin films and ultrathin films, such as high surface area, controlled nanostructure for effective charge transfer, and special physical and chemical properties, to develop new thin film devices. This paper is therefore intended to provide a concise critical review and research directions on most thin film devices, including thin film transistors, data storage memory, solar cells, organic light-emitting diodes, thermoelectric devices, smart materials, sensors, and actuators. The thin film devices may consist of organic, inorganic, and composite thin layers, and share similar functionality, properties, and fabrication routes. Therefore, due to the multidisciplinary nature of thin film devices, knowledge and advances already made in one area may be applicable to other similar areas. Owing to the importance of developing low-cost, scalable, and vacuum-free fabrication routes, this paper focuses on thin film devices that may be processed and deposited from solution.

  20. A thin-film device for detecting hydrogen

    NARCIS (Netherlands)

    Westerwaal, R.J.; Szilagyi, P.A.; Dam, B.

    2014-01-01

    The present invention relates to a thin-film device, to a method for producing a thin-film device, to a protective layer for shielding an oxygen, moisture and/or carbon monoxide sensitive surface, to a method for shielding such a surface, to a method for forming a metal framework material, to a hydr

  1. Optical noise suppression device and method. [laser light exposing film

    Science.gov (United States)

    Horner, J. L. (Inventor)

    1976-01-01

    A device and method is disclosed for suppression of optical noise in an optical spatial filtering system using highly coherent light. In the disclosed embodiment, input photographic film to be processed in the system, and output photographic film to be exposed, are each mounted on lateral translation devices. During application of the coherent light for exposure of the output film, the two translation devices are moved in synchronism by a motor-driven gear and linkage assembly. The ratio of the resulting output film translation to the input film translation is equal to the magnification of the optical data processing system. The noise pattern associated with the lenses and other elements in the optical processing system remains stationary while the image-producing light moves laterally through the pattern with the output film, thus averaging out the noise effect at the output film.

  2. Optical modeling and simulation of thin-film photovoltaic devices

    CERN Document Server

    Krc, Janez

    2013-01-01

    In wafer-based and thin-film photovoltaic (PV) devices, the management of light is a crucial aspect of optimization since trapping sunlight in active parts of PV devices is essential for efficient energy conversions. Optical modeling and simulation enable efficient analysis and optimization of the optical situation in optoelectronic and PV devices. Optical Modeling and Simulation of Thin-Film Photovoltaic Devices provides readers with a thorough guide to performing optical modeling and simulations of thin-film solar cells and PV modules. It offers insight on examples of existing optical models

  3. Magnesium diboride thin films and devices

    Science.gov (United States)

    Cui, Yi

    Magnesium diboride (MgB2) is a binary compound superconductor with a superconducting transition temperature Tc of ˜40 K. MgB2 has two conduction bands: a two-dimensional sigma band and a three-dimensional pi band with weak interband scattering. The two gap superconductivity in MgB2 gives rise to many interesting physical properties not possible in other superconductors. The relatively high Tc combined with phonon mediated superconductivity and relatively long coherence length makes MgB2 promising for electronics applications like rapid single flux quantum (RSFQ) logics and superconducting quantum interference devices (SQUID). The high current density and record-high upper critical field in pure or alloyed MgB2 are also attractive to a variety of high field applications including cryogen-free Magnetic Resonance Imaging (MRI) systems. MgB2 may also be used in RF cavity coatings due to its low surface resistance and in photo detection due to its fast photoresponse coupled with relatively high Tc. High quality epitaxial thin films are produced by the hybrid physical-chemical vapor deposition (HPCVD) technique. The HPCVD MgB2 thin films have the highest Tc and lowest resistivity with sharp transition of all MgB2 materials reported. The HPCVD MgB2 material is free of dendritic flux jumps due to its low resistivity. The root-mean-square (RMS) surface roughness of HPCVD MgB2 films can be ˜1 nm when ˜1% of nitrogen is added to the hydrogen carrier gas during the growth. The stability of MgB2 films in water is studied; it is found that degradation can be prevented by a thin (10 nm) MgO layer deposited on the film surface. The Tc is enhanced by tensile strain due to the Volmer-Weber growth mode and the mismatches between MgB2 and the substrate in the lattice constants and the coefficients of thermal expansion. High quality superconductor-insulator-superconductor Josephson tunnel junctions were made with various barrier formation techniques. The junction critical current

  4. Front and backside processed thin film electronic devices

    Science.gov (United States)

    Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang; Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.

    2012-01-03

    This invention provides thin film devices that have been processed on their front- and backside. The devices include an active layer that is sufficiently thin to be mechanically flexible. Examples of the devices include back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

  5. Digital Badging at The Open University: Recognition for Informal Learning

    Science.gov (United States)

    Law, Patrina

    2015-01-01

    Awarding badges to recognise achievement is not a new development. Digital badging now offers new ways to recognise learning and motivate learners, providing evidence of skills and achievements in a variety of formal and informal settings. Badged open courses (BOCs) were piloted in various forms by the Open University (OU) in 2013 to provide a…

  6. Electrocaloric devices based on thini-film heat switches

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, Richard I [Los Alamos National Laboratory; Malloy, Kevin J [UNM

    2009-01-01

    We describe a new approach to refrigeration and electrical generation that exploits the attractive properties of thin films of electrocaloric materials. Layers of electrocaloric material coupled with thin-film heat switches can work as either refrigerators or electrical generators, depending on the phasing of the applied voltages and heat switching. With heat switches based on thin layers of liquid crystals, the efficiency of these thin-film heat engines can be at least as high as that of current thermoelectric devices. Advanced heat switches would enable thin-film heat engines to outperform conventional vaporcompression devices.

  7. Measurement error in longitudinal film badge data

    CERN Document Server

    Marsh, J L

    2002-01-01

    Initial logistic regressions turned up some surprising contradictory results which led to a re-sampling of Sellafield mortality controls without the date of employment matching factor. It is suggested that over matching is the cause of the contradictory results. Comparisons of the two measurements of radiation exposure suggest a strongly linear relationship with non-Normal errors. A method has been developed using the technique of Regression Calibration to deal with these in a case-control study context, and applied to this Sellafield study. The classical measurement error model is that of a simple linear regression with unobservable variables. Information about the covariates is available only through error-prone measurements, usually with an additive structure. Ignoring errors has been shown to result in biased regression coefficients, reduced power of hypothesis tests and increased variability of parameter estimates. Radiation is known to be a causal factor for certain types of leukaemia. This link is main...

  8. An overview of thin film nitinol endovascular devices.

    Science.gov (United States)

    Shayan, Mahdis; Chun, Youngjae

    2015-07-01

    Thin film nitinol has unique mechanical properties (e.g., superelasticity), excellent biocompatibility, and ultra-smooth surface, as well as shape memory behavior. All these features along with its low-profile physical dimension (i.e., a few micrometers thick) make this material an ideal candidate in developing low-profile medical devices (e.g., endovascular devices). Thin film nitinol-based devices can be collapsed and inserted in remarkably smaller diameter catheters for a wide range of catheter-based procedures; therefore, it can be easily delivered through highly tortuous or narrow vascular system. A high-quality thin film nitinol can be fabricated by vacuum sputter deposition technique. Micromachining techniques were used to create micro patterns on the thin film nitinol to provide fenestrations for nutrition and oxygen transport and to increase the device's flexibility for the devices used as thin film nitinol covered stent. In addition, a new surface treatment method has been developed for improving the hemocompatibility of thin film nitinol when it is used as a graft material in endovascular devices. Both in vitro and in vivo test data demonstrated a superior hemocompatibility of the thin film nitinol when compared with commercially available endovascular graft materials such as ePTFE or Dacron polyester. Promising features like these have motivated the development of thin film nitinol as a novel biomaterial for creating endovascular devices such as stent grafts, neurovascular flow diverters, and heart valves. This review focuses on thin film nitinol fabrication processes, mechanical and biological properties of the material, as well as current and potential thin film nitinol medical applications.

  9. Solid-State Imaging Device With Carbon Film

    Science.gov (United States)

    Frazer, Robert E.

    1992-01-01

    Performance of solid-state imaging device enhanced by coating surface through which photons enter with thin film of carbon or diamondlike carbon. Film beneficial in two ways: acts as antireflection coat, and helps to dissipate undesired static electric charges that otherwise accumulate on surface.

  10. Badges: A Common Currency for Learning

    Science.gov (United States)

    Bowen, Kyle; Thomas, Andrea

    2014-01-01

    Digital Badges--icons that can represent skills and achievements at a more fine-grained level than a degree--give colleges and universities a new way to document learning outcomes and to map the pathways students follow to earn a degree. They also provide a common currency to denote learning outcomes and give employers a visual representation and…

  11. Digital Badge Systems: The Promise and Potential

    Science.gov (United States)

    Thigpen, Kamila

    2014-01-01

    Digital badges--defined as digital credentials that convey an array of skills, interests, and achievements--are steadily growing in acceptance as a way to validate learning that takes place not only in school but also at home and in a number of other out-of-school settings. This report builds on the growing body of literature about digital badge…

  12. Improved Response of ZnO Films for Pyroelectric Devices

    Directory of Open Access Journals (Sweden)

    Shih-Yuan Yu

    2012-12-01

    Full Text Available Increasing the temperature variation rate is a useful method for enhancing the response of pyroelectric devices. A three-dimensional ZnO film was fabricated by the aerosol deposition (AD rapid process using the shadow mask method, which induces lateral temperature gradients on the sidewalls of the responsive element, thereby increasing the temperature variation rate. To enhance the quality of the film and reduce the concentration of defects, the film was further treated by laser annealing, and the integration of a comb-like top electrode enhanced the voltage response and reduced the response time of the resulting ZnO pyroelectric devices.

  13. Organic nanostructured thin film devices and coatings for clean energy

    CERN Document Server

    Zhang, Sam

    2010-01-01

    Authored by leading experts from around the world, the three-volume Handbook of Nanostructured Thin Films and Coatings gives scientific researchers and product engineers a resource as dynamic and flexible as the field itself. The first two volumes cover the latest research and application of the mechanical and functional properties of thin films and coatings, while the third volume explores the cutting-edge organic nanostructured devices used to produce clean energy. This third volume, Organic Nanostructured Thin Film Devices and Coatings for Clean Energy, addresses various aspects of the proc

  14. Screen-printed piezoceramic thick films for miniaturised devices

    DEFF Research Database (Denmark)

    Lou-Moeller, R.; Hindrichsen, Christian Carstensen; Thamdrup, Lasse Højlund;

    2007-01-01

    The development towards smaller devices with more functions integrated calls for new and improved manufacturing processes. The screen-printing process is quite well suited for miniaturised and integrated devices, since thick films can be produced in this manner without the need for further machin...

  15. Sputtering materials for VLSI and thin film devices

    CERN Document Server

    Sarkar, Jaydeep

    2010-01-01

    An important resource for students, engineers and researchers working in the area of thin film deposition using physical vapor deposition (e.g. sputtering) for semiconductor, liquid crystal displays, high density recording media and photovoltaic device (e.g. thin film solar cell) manufacturing. This book also reviews microelectronics industry topics such as history of inventions and technology trends, recent developments in sputtering technologies, manufacturing steps that require sputtering of thin films, the properties of thin films and the role of sputtering target performance on overall p

  16. Organic thin film devices with stabilized threshold voltage and mobility, and method for preparing the devices

    Science.gov (United States)

    Nastasi, Michael Anthony; Wang, Yongqiang; Fraboni, Beatrice; Cosseddu, Piero; Bonfiglio, Annalisa

    2013-06-11

    Organic thin film devices that included an organic thin film subjected to a selected dose of a selected energy of ions exhibited a stabilized mobility (.mu.) and threshold voltage (VT), a decrease in contact resistance R.sub.C, and an extended operational lifetime that did not degrade after 2000 hours of operation in the air.

  17. Large-Scale Graphene Film Deposition for Monolithic Device Fabrication

    Science.gov (United States)

    Al-shurman, Khaled

    Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors. The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an urgent need for a new platform material to replace Si. Graphene is considered a promising material with enormous potential applications in many electronic and optoelectronics devices due to its superior properties. There are several techniques to produce graphene films. Among these techniques, chemical vapor deposition (CVD) offers a very convenient method to fabricate films for large-scale graphene films. Though CVD method is suitable for large area growth of graphene, the need for transferring a graphene film to silicon-based substrates is required. Furthermore, the graphene films thus achieved are, in fact, not single crystalline. Also, graphene fabrication utilizing Cu and Ni at high growth temperature contaminates the substrate that holds Si CMOS circuitry and CVD chamber as well. So, lowering the deposition temperature is another technological milestone for the successful adoption of graphene in integrated circuits fabrication. In this research, direct large-scale graphene film fabrication on silicon based platform (i.e. SiO2 and Si3N4) at low temperature was achieved. With a focus on low-temperature graphene growth, hot-filament chemical vapor deposition (HF-CVD) was utilized to synthesize graphene film using 200 nm thick nickel film. Raman spectroscopy was utilized to examine graphene formation on the bottom side of the Ni film

  18. Gamification of Nursing Education With Digital Badges.

    Science.gov (United States)

    White, Meagan; Shellenbarger, Teresa

    2017-08-16

    Digital badges (DBs) serve as an innovative approach to gamifying nursing education by engaging socially connected, technologically savvy nursing students in learning. Because assessment and credentialing mechanisms are housed and managed online, DBs are designed as visible indicators of accomplishment and skill. This article describes important considerations for faculty when incorporating game-based pedagogies such as DB into nursing education and identifies potential pitfalls with DB use that faculty should consider.

  19. Human Connections in Red Badge of Courage

    Directory of Open Access Journals (Sweden)

    Syed Afroz Ashrafi

    2016-05-01

    Full Text Available The paper Human connection in Red badge of Courage sought to reestablish the notion that humanity survives the ravages of war, the war that kills and alienates a good chunk of human populace. The sounds of bullets cannot soften the tissues of heart, rather it only appalls humanity. Crane’s human connection is stressed as the succor for the tormented and oppressed nations mainly through wars.

  20. Optoelectronics Devices Based on Zinc Oxide Thin Films and Nanostructures

    OpenAIRE

    Chu, Sheng

    2011-01-01

    Optoelectronics devices based on ZnO thin films and nanostructures are discussed in this dissertation. A ZnO homojunction LED was demonstrated. Sb-doped p-type ZnO and Ga-doped n-type ZnO on Si (100) substrate were used for the LED device. After achieving ohmic contacts on both types of ZnO, the device showed rectifying current-voltage (I-V) characteristics. Under forward bias, the device successfully showed ultraviolet emissions. The emission properties were analyzed and the emission was con...

  1. Surface acoustic wave devices including Langmuir-Blodgett films (Review)

    Science.gov (United States)

    Plesskii, V. P.

    1991-06-01

    Recent theoretical and experimental research related to the use of Langmuir-Blodgett (LB) films in surface acoustic wave (SAW) devices is reviewed. The sensitivity of the different cuts of quartz and lithium niobate to inertial loading is investigated, and it is shown that some cuts in lithium niobate are twice as sensitive to mass loading than the commonly used YZ-cut. The large variety of organic compounds suitable for the production of LB films makes it possible to create SAW sensors reacting selectively to certain substances. The existing SAW sensors based on LB films are characterized by high sensitivity and fast response.

  2. Electrochromic Devices Based on Porous Tungsten Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Y. Djaoued

    2012-01-01

    Full Text Available Recent developments in the synthesis of transition metal oxides in the form of porous thin films have opened up opportunities in the construction of electrochromic devices with enhanced properties. In this paper, synthesis, characterization and electrochromic applications of porous WO3 thin films with different nanocrystalline phases, such as hexagonal, monoclinic, and orthorhombic, are presented. Asymmetric electrochromic devices have been constructed based on these porous WO3 thin films. XRD measurements of the intercalation/deintercalation of Li+ into/from the WO3 layer of the device as a function of applied coloration/bleaching voltages show systematic changes in the lattice parameters associated with structural phase transitions in LixWO3. Micro-Raman studies show systematic crystalline phase changes in the spectra of WO3 layers during Li+ ion intercalation and deintercalation, which agree with the XRD data. These devices exhibit interesting optical modulation (up to ~70% due to intercalation/deintercalation of Li ions into/from the WO3 layer of the devices as a function of applied coloration/bleaching voltages. The obtained optical modulation of the electrochromic devices indicates that, they are suitable for applications in electrochromic smart windows.

  3. Characterizations of SWNT films to obtain organic optoelectronic device anodes

    Energy Technology Data Exchange (ETDEWEB)

    Antony, R.; Ratier, B. [XLIM UMR 6172, Universite de Limoges, CNRS, 123 av. Albert Thomas, 87060 Limoges Cedex (France); Colas, M. [SPCTS, UMR CNRS6638, Faculte des Sci. et Tech., 123, av. Albert Thomas, 87060 Limoges Cedex (France); Banoukepa, G.R. de

    2010-04-15

    Organic devices such as solar cells or light emitting diodes (OLEDs) have been intensively studied for the last decade, and have now the potential to reach the market for various applications. Nevertheless, various reports have shown that devices based on Indium Tin Oxide anode present a reduced efficiency due to indium diffusion into organic active layers. In this context, our work focus on the development and the characterization of alternative anodes based on Single Walled Carbon Nanotube (SWNT) Films. In particular, this work is devoted to the morphology and charge transport properties of carbon nanotube thin layers. SWNT films were prepared on glass substrates using the vacuum filtration method reported by Wu et al. As a second step, the films were dipped in a nitric acid and subsequently dried in order to reduce their sheet resistances. Raman spectroscopy is then used to chemically map the film surface, and allow us to assess the homogeneity of the achieved films. Finally, optical and electrical characterizations (measurements of the sheet resistance and optical transmission) provide evidence of a correlation between the quality of the surface and the nature of charge transport occurring in the prepared SWNT films (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Thin-film Rechargeable Lithium Batteries for Implantable Devices

    Science.gov (United States)

    Bates, J. B.; Dudney, N. J.

    1997-05-01

    Thin films of LiCoO{sub 2} have been synthesized in which the strongest x ray reflection is either weak or missing, indicating a high degree of preferred orientation. Thin film solid state batteries with these textured cathode films can deliver practical capacities at high current densities. For example, for one of the cells 70% of the maximum capacity between 4.2 V and 3 V ({approximately}0.2 mAh/cm{sup 2}) was delivered at a current of 2 mA/cm{sup 2}. When cycled at rates of 0.1 mA/cm{sup 2}, the capacity loss was 0.001%/cycle or less. The reliability and performance of Li LiCoO{sub 2} thin film batteries make them attractive for application in implantable devices such as neural stimulators, pacemakers, and defibrillators.

  5. Thin-film rechargeable lithium batteries for implantable devices

    Energy Technology Data Exchange (ETDEWEB)

    Bates, J.b.; Dudney, N.J.

    1997-05-01

    Thin films of LiCoO{sub 2} have been synthesized in which the strongest x-ray reflection is either weak or missing, indicating a high degree of preferred orientation. Thin-film solid state batteries with these textured cathode films can deliver practical capacities at high current densities. For example, for one of the cells 70% of the maximum capacity between 4.2 V and 3 V ({approximately}0.2 mAh/cm{sup 2}) was delivered at a current of 2 mA/cm{sup 2}. When cycled at rates of 0.1 mA/cm{sup 2}, the capacity loss was 0.001 %/cycle or less. The reliability and performance of Li-LiCoO{sub 2} thin-film batteries make them attractive for application in implantable devices such as neural stimulators, pacemakers, and defibrillators.

  6. Employer Perceptions of Critical Information Literacy Skills and Digital Badges

    Science.gov (United States)

    Raish, Victoria; Rimland, Emily

    2016-01-01

    Digital badges are an educational innovation used to measure learning of specific skills, such as information literacy. However, few studies have quantitatively surveyed employers for their perceptions about information literacy skills or digital badges. An online survey was developed and sent to employers to gauge perceptions of information…

  7. Employer Perceptions of Critical Information Literacy Skills and Digital Badges

    Science.gov (United States)

    Raish, Victoria; Rimland, Emily

    2016-01-01

    Digital badges are an educational innovation used to measure learning of specific skills, such as information literacy. However, few studies have quantitatively surveyed employers for their perceptions about information literacy skills or digital badges. An online survey was developed and sent to employers to gauge perceptions of information…

  8. The Effectiveness of Digital Badges on Student Online Contributions

    Science.gov (United States)

    Chou, Chientzu Candace; He, Shi-Jen

    2017-01-01

    Digital badges have been increasingly used to encourage users to achieve specific goals in learning. Recent studies have shown that badges can be effective to incentivize learners to complete specific tasks or increase learning participation in online learning environments. This study utilized a mixed research method to examine the impact of a…

  9. Synthesis, deposition and characterization of ferroelectric films for electrooptic devices

    Science.gov (United States)

    Tunaboylu, Bahadir

    The use of integrable ferroelectric electro-optic thin films is a revolutionary approach in the development of high-speed, low-voltage and high-contrast ratio integrated electro-optic spatial light modulators (SLM) for free-space optoelectronic interconnects. Thin films offer improved performance over bulk ferroelectric (FE) materials because of their lower modulator capacitance and operation at high speeds with low switching energies. Integration of ferroelectric thin films with silicon technology will also impact both the uncooled infrared sensor and dynamic and nonvolatile memory technologies. Ferroelectrics such as lead lanthanum zirconate titanate (PLZT) and patassium tantalate niobate (KTN) present great potential for SLMs due to their large electro-optic (EO) effect in the bulk form. The development of thin-film SLMs require electro-optic films of high optical quality with good dielectric and EO properties. High quality thin films of PLZT and KTN were deposited using RF magnetron sputtering on r-plane sapphire substrates which offer integration capability with semiconductor devices. PLZT films with extremely large peak dielectric constant, 2800 at the Curie temperature of 180sp°C, were achieved with remarkably low dissipation loss factor dielectric frequency dispersion was determined to be very small up to 1 Mhz. Also, the absorption of the light in the films was very low. A giant effective quadratic electrooptic effect was demonstrated in PLZT films. These results represent a huge leap forward for the FE-SLM technology with respect to the goal of fully integrated thin film electrooptic light modulators. Microstructural development and phase transformation kinetics in PLZT films were also analyzed for the first time and are presented here. Energy required for the formation of desirable perovskite phase was determined to be 322 kJ/mol. Single-phase PLZT films with larger average grain size showed higher dielectric constants and better EO properties as

  10. Thin Film Compound Semiconductor Devices for Photonic Interconnects

    Science.gov (United States)

    Calhoun, Kenneth Harold

    The research conducted for this doctoral dissertation involved the experimental investigation of thin film compound devices for use as photonic interconnection components in both external and direct modulated interconnection configurations. The devices were fabricated using a modified epitaxial liftoff procedure developed at Georgia Tech. This technique, by which single crystal semiconductor layers were separated from their growth substrate and subsequently deposited onto host substrates, allowed the development of novel photonic interconnection elements. It also facilitated the investigation of fundamental optical phenomena in compound semiconductors. Specifically, this work focused on an experimental study of the Franz-Keldysh electrorefractive effect in thin film semiconductor structures. This aspect of the research resulted in the first reported direct measurement of electrorefraction in GaAs at large electric fields (10 ^5 V/cm) and at photon energies within several meV of the band edge of GaAs. Related to this effort was the investigation of thin film, surface-normal optical modulators based on the bulk Franz-Keldysh effect. The novel modulators fabricated for this research demonstrated the largest contrast ratios ever reported for surface-normal Franz-Keldysh devices. Further investigation indicated that, with additional optimization, these thin film elements can achieve further improvements in performance. Such devices would present a low cost, easily manufactured alternative to conventional modulators, which are typically quite complex and expensive to fabricate. Finally, as an alternative to externally modulated interconnection schemes, a novel stacked wafer architecture was demonstrated. This configuration, which facilitated through-wafer optical communication, utilized thin film InP/InGaAsP emitters and detectors which were quasi-monolithically integrated onto silicon substrates using the modified epitaxial liftoff process. This through-wafer scheme is

  11. Microfabricated structures and devices featuring nanostructured titania thin films

    Science.gov (United States)

    Monkowski, Adam J.

    2007-05-01

    When titanium reacts with hydrogen peroxide at 80°C--100°C, a nanostructured titania (NST) thin film is formed on the titanium surface. This nanostructured film is particularly suited for integration with thin film and bulk microfabrication techniques. The ability to manufacture devices in a batch format is a principal advantage of microfabrication-based production. To reliably produce arrays of micro-patterned NST thin films on the wafer scale, a patterning guideline must be considered. The formation of NST relies on a re-deposition process; adequate ti-peroxo species must be generated and remain at the solid-solution interface. Numerical analysis of the characteristic transient diffusion behavior for various micro-patterns has been compared with experimental data to generate a criterion to guide the design of NST micro-patterns. Wafer scale arrays of NST micro gas-sensors have been fabricated using standard thin film techniques. Sensing elements are 20 mum on a side. High sensitivity to hydrogen is achieved by modification of the sensors with platinum nanoparticles. When exposed to a 10 mT partial pressure of hydrogen at 250°C, the functionalized devices exhibit more than one order of magnitude resistance decrease with a response time of approximately 7 sec. Titanium microstructures formed using the titanium ICP deep etch (TIDE) process have been integrated with NST films to produce an ordered nanostructure-microstructure composite (3D-NST). The process developed allows for the incorporation of a planar top surface, advantageous for bonding and sealing applications, in which the nanostructured thin film is formed only on feature sidewalls and floors. When titanium microstructures are spaced less than 1 mum apart, titania nanostructures bridge adjacent features. NST and 3D-NST structures have been assembled and tested in a dye-sensitized solar cell (DSSC) device. The NST film is approximately 900nm thick; this yielded a DSSC with an efficiency of 1.8%, similar

  12. Nanostructured thin film polymer devices for constant-rate protein delivery.

    Science.gov (United States)

    Bernards, Daniel A; Lance, Kevin D; Ciaccio, Natalie A; Desai, Tejal A

    2012-10-10

    Herein long-term delivery of proteins from biodegradable thin film devices is demonstrated, where a nanostructured polymer membrane controls release. Protein was sealed between two poly(caprolactone) films, which generated the thin film devices. Protein release for 210 days was shown in vitro, and stable activity was established through 70 days with a model protein. These thin film devices present a promising delivery platform for biologic therapeutics, particularly for application in constrained spaces.

  13. Thin film photovoltaic devices with a minimally conductive buffer layer

    Science.gov (United States)

    Barnes, Teresa M.; Burst, James

    2016-11-15

    A thin film photovoltaic device (100) with a tunable, minimally conductive buffer (128) layer is provided. The photovoltaic device (100) may include a back contact (150), a transparent front contact stack (120), and an absorber (140) positioned between the front contact stack (120) and the back contact (150). The front contact stack (120) may include a low resistivity transparent conductive oxide (TCO) layer (124) and a buffer layer (128) that is proximate to the absorber layer (140). The photovoltaic device (100) may also include a window layer (130) between the buffer layer (128) and the absorber (140). In some cases, the buffer layer (128) is minimally conductive, with its resistivity being tunable, and the buffer layer (128) may be formed as an alloy from a host oxide and a high-permittivity oxide. The high-permittivity oxide may further be chosen to have a bandgap greater than the host oxide.

  14. Nobels Nobels laureates photographed by Peter Badge

    CERN Document Server

    2008-01-01

    A unique photographic record of all living Nobel laureates. In this handsome coffee-table book, photographer Peter Badge captures the likeness of every living Nobel laureate in a lasting black-and-white image -- more than 300 striking portraits in all. Brief biographical sketches accompanying the large-scale photographs pay homage to each laureate's singular contribution to science, literature or world peace. Bringing readers face-to-face with Nelson Mandela, Jimmy Carter, the Dalai Lama, James Watson, Gabriel García Márquez, Toni Morrison, Rita Levi-Montalcini, Linda Buck, and Paul Samuelson among many others, NOBELS offers an intimate and compelling look at well-known honorees as well as lesser-known recipients. A fascinating word/image tableau.

  15. Fundamentals of polycrystalline thin film materials and devices

    Energy Technology Data Exchange (ETDEWEB)

    Baron, B.N.; Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E. (Delaware Univ., Newark, DE (USA). Inst. of Energy Conversion)

    1991-01-01

    This report presents the results of a one-year research program on polycrystalline thin-film solar cells. The research was conducted to better understand the limitations and potential of solar cells using CuInSe{sub 2} and CdTe by systematically investigating the fundamental relationships linking material processing, material properties, and device behavior. By selenizing Cu and In layers, we fabricated device-quality CuInSe{sub 2} thin films and demonstrated a CuInSe{sub 2} solar cell with 7% efficiency. We added Ga, to increase the band gap of CuInSe{sub 2} devices to increase the open-circuit voltage to 0.55 V. We fabricated and analyzed Cu(InGa)Se{sub 2}/CuInSe{sub 2} devices to demonstrate the potential for combining the benefits of higher V{sub oc} while retaining the current-generating capacity of CuInSe{sub 2}. We fabricated an innovative superstrate device design with more than 5% efficiency, as well as a bifacial spectral-response technique for determining the electron diffusion length and optical absorption coefficient of CuInSe{sub 2} in an operational cell. The diffusion length was found to be greater than 1 {mu}m. We qualitatively modeled the effect of reducing heat treatments in hydrogen and oxidizing treatments in air on the I-V behavior of CuInSe{sub 2} devices. We also investigated post-deposition heat treatments and chemical processing and used them to fabricate a 9.6%-efficient CdTe/CdS solar cell using physical vapor deposition.

  16. Aligning the use of portfolios with digital badging.

    Science.gov (United States)

    Doherty, Iain; Sharma, Neel

    2015-10-01

    While the place of portfolios in medical training is established, there are limits to their use. This article discusses the potential use of digital badges to complement portfolios, as these provide a transparent overview of a learner's level of competence.

  17. Magnetic field effect in organic films and devices

    Science.gov (United States)

    Gautam, Bhoj Raj

    In this work, we focused on the magnetic field effect in organic films and devices, including organic light emitting diodes (OLEDs) and organic photovoltaic (OPV) cells. We measured magnetic field effect (MFE) such as magnetoconductance (MC) and magneto-electroluminescence (MEL) in OLEDs based on several pi- conjugated polymers and small molecules for fields |B|˜2mT. Magnetic field effect (MFE) measured on three isotopes of Poly (dioctyloxy) phenylenevinylene (DOO-PPV) showed that both regular and ultra-small effects are isotope dependent. This indicates that MFE response in OLED is mainly due to the hyperfine interaction (HFI). We also performed spectroscopy of the MFE including magneto-photoinduced absorption (MPA) and magneto-photoluminescence (MPL) at steady state conditions in several systems. This includes pristine Poly[2-methoxy-5-(2-ethylhexyl-oxy)-1,4-phenylene-vinylene] (MEH-PPV) films, MEH-PPV films subjected to prolonged illumination, and MEH-PPV/[6,6]-Phenyl C61 butyric acid methyl ester (PCBM) blend, as well as annealed and pristine C60 thin films. For comparison, we also measured MC and MEL in organic diodes based on the same materials. By directly comparing the MPA and MPL responses in films to MC and MEL in organic diodes based on the same active layers, we are able to relate the MFE in organic diodes to the spin densities of the excitations formed in the device, regardless of whether they are formed by photon absorption or carrier injection from the electrodes. We also studied magneto-photocurrent (MPC) and power conversion efficiency (PCE) of a 'standard' Poly (3-hexylthiophene)/PCBM device at various Galvinoxyl radical wt%. We found that the MPC reduction with Galvinoxyl wt% follows the same trend as that of the PCE enhancement. In addition, we also measured the MPC response of a series of OPV cells. We attribute the observed broad MPC to short-lived charge transfer complex species, where spin mixing is caused by the difference, Deltag of the

  18. Chalcogenide photovoltaics physics, technologies, and thin film devices

    CERN Document Server

    Scheer, Roland

    2011-01-01

    This first comprehensive description of the most important material properties and device aspects closes the gap between general books on solar cells and journal articles on chalcogenide-based photovoltaics. Written by two very renowned authors with years of practical experience in the field, the book covers II-VI and I-III-VI2 materials as well as energy conversion at heterojunctions. It also discusses the latest semiconductor heterojunction models and presents modern analysis concepts. Thin film technology is explained with an emphasis on current and future techniques for mass production, a

  19. Thin aligned organic polymer films for liquid crystal devices

    CERN Document Server

    Foster, K E

    1997-01-01

    This project was designed to investigate the possibility of producing alignment layers for liquid crystal devices by cross-linking thin films containing anisotropic polymer bound chromophores via irradiation with polarised ultraviolet light. Photocross-linkable polymers find use in microelectronics, liquid crystal displays, printing and UV curable lacquers and inks; so there is an increasing incentive for the development of new varieties of photopolymers in general. The synthesis and characterisation of two new photopolymers that are suitable as potential alignment layers for liquid crystal devices are reported in this thesis. The first polymer contains the anthracene chromophore attached via a spacer unit to a methacrylate backbone and the second used a similarly attached aryl azide group. Copolymers of the new monomers with methyl methacrylate were investigated to establish reactivity ratios in order to understand composition drift during polymerisation.

  20. SEMICONDUCTOR DEVICES: CuPc/C60 heterojunction thin film optoelectronic devices

    Science.gov (United States)

    Murtaza, Imran; Qazi, Ibrahim; Karimov, Khasan S.

    2010-06-01

    The optoelectronic properties of heterojunction thin film devices with ITO/CuPc/C60/Al structure have been investigated by analyzing their current-voltage characteristics, optical absorption and photocurrent. In this organic photovoltaic device, CuPc acts as an optically active layer, C60 as an electron-transporting layer and ITO and Al as electrodes. It is observed that, under illumination, excitons are formed, which subsequently drift towards the interface with C60, where an internal electric field is present. The excitons that reach the interface are subsequently dissociated into free charge carriers due to the electric field present at the interface. The experimental results show that in this device the total current density is a function of injected carriers at the electrode-organic semiconductor surface, the leakage current through the organic layer and collected photogenerated current that results from the effective dissociation of excitons.

  1. Developing a conceptual model for facilitating the issuing of digital badges in a resource constrained environment

    CSIR Research Space (South Africa)

    Salerno, S

    2015-09-01

    Full Text Available for the issuing, managing and receiving of digital badges in connected environments. These Mozilla Badges are issued to learners by facilitators or organisational representatives acting as a form of accreditation for the skills said individual has learnt...

  2. A scoping review towards the conceptualization of a digital Open Badges ecosystem in South Africa

    CSIR Research Space (South Africa)

    Motheeram, Preia

    2016-11-01

    Full Text Available A scoping review was conducted towards supporting the conceptualization of a Digital Open Badge Ecosystem for South Africa. The scoping review intends to address the conceptualization of a digital Open Badges ecosystem for South Africa by: (1...

  3. Mechanical properties of thin film Parylene-metal-Parylene devices

    Directory of Open Access Journals (Sweden)

    Curtis Dixon Lee

    2015-09-01

    Full Text Available Structures and testing methods for measuring the adhesion strength, minimum bending diameter, and bending fatigue performance of thin film polymer electronic architectures were developed and applied to Parylene-metal-Parylene systems with and without the moisture barrier Al2O3 (deposited using atomic layer deposition (ALD. Parylene-metal-Parylene interfaces had the strongest average peel test strength and Parylene-Parylene interfaces had the weakest peel. Layers of ALD Al2O3 deposited within the device increased the average peel strength for Parylene-Parylene interfaces when combined with silane A-174, but did not increase the Parylene-metal-Parylene interface. Metal traces in the middle of 24 µm thick Parylene-metal-Parylene devices had a minimum bending diameter of ~130 µm before breaking and being measured as an open circuit. The addition of one layer of Al2O3 above the traces allowed them to be completely creased when bent away from the Al2O3 layer without producing an open circuit, but increased the minimum bending diameter to ~450 µm when bent away from the Al2O3. Although fatigue testing produced cracks in all devcies after 100k bends, the insulation of the Parylene-metal-Parylene devices without Al2O3 performed well with electrochemical impedance spectroscopy (EIS showing only small decreases in impedance magnitude and small increases of impedance phase at low frequencies. However, devices with Al2O3 failed during EIS due to Al2O3 being deteriorated by water.

  4. Chitosan microspheres in PLG films as devices for cytarabine release.

    Science.gov (United States)

    Blanco, M D; Gómez, C; Olmo, R; Muñiz, E; Teijón, J M

    2000-07-20

    Cytarabine was included in chitosan microspheres and several of these microspheres were embedded in a poly(lactide-co-glycolide) (PLG) film to constitute a comatrix system, to develop a prolonged release form. Chitosan microspheres, in the range of 92+/-65 microm, having good spherical geometry and a smooth surface incorporating cytarabine, were prepared. The cytarabine amount included in chitosan microspheres was 43.7 microg of ara-C per milligram microsphere. The incorporation efficiency of the cytarabine in microspheres was 70.6%. Total cytarabine release from microspheres in vitro was detected at 48 h. Inclusion of cytarabine-loaded microspheres in poly(lactide-co-glycolide) film initiated a slower release of the drug and, in this way, the maximum of cytarabine released (80%) took place in vitro at 94.5 h. Comatrices, with 8.7 mg of cytarabine, signifying a dose of 34.5 microg/kg, were subcutaneously implanted in the back of rats. Maximum plasma cytarabine concentration was 18.5+/-1.5 microg/ml, 48 h after the device implantation and the drug was detected in plasma for 13 days. The histological studies show a slow degradative process. After 6 months of implantation, most of the microspheres of the matrix seemed to be intact, the comatrix appeared surrounded by conjunctive tissue and small blood vessels and nerve packets were detected in the periphery of the implant.

  5. Digital Badges in Science: A Novel Approach to the Assessment of Student Learning

    Science.gov (United States)

    Hensiek, Sarah; DeKorver, Brittland K.; Harwood, Cynthia J.; Fish, Jason; O'Shea, Kevin; Towns, Marcy

    2017-01-01

    Digital badging is an innovative method of valid, evidence-based assessment that may be used to assess hands-on skills in undergraduate science laboratories, in research laboratories, and in fieldwork. A digital badge contains information about who was awarded the badge, the criteria used, the evidence submitted, the issuer, the date issued, and…

  6. Digital Badges: Recognizing, Assessing, and Motivating Learners in and out of School Contexts

    Science.gov (United States)

    Ian O'Byrne, W.; Schenke, Katerina; Willis, James E., III.; Hickey, Daniel T.

    2015-01-01

    Digital badges are web-enabled tokens of accomplishment that contain specific claims and evidence about learning and achievement along with detailed evidence supporting those claims. Badges traditionally consist of an image and relevant metadata (e.g., badge name, description, criteria, issuer, evidence, date issued, standards, and tags). This…

  7. Adding Badging to a Marketing Simulation to Increase Motivation to Learn

    Science.gov (United States)

    Saxton, M. Kim

    2015-01-01

    Badging has become a popular tool for obtaining social recognition for personal accomplishments. This innovation describes a way to add badging to a marketing simulation to increase student motivation to achieve the simulation's goals. Assessments indicate that badging both motivates students to perform better and helps explain students' perceived…

  8. Using Organic Light-Emitting Electrochemical Thin-Film Devices to Teach Materials Science

    Science.gov (United States)

    Sevian, Hannah; Muller, Sean; Rudmann, Hartmut; Rubner, Michael F.

    2004-01-01

    Materials science can be taught by applying organic light-emitting electrochemical thin-film devices and in this method students were allowed to make a light-emitting device by spin coating a thin film containing ruthenium (II) complex ions onto a glass slide. Through this laboratory method students are provided with the opportunity to learn about…

  9. Polymer−metal organic framework composite films as affinity layer for capacitive sensor devices

    NARCIS (Netherlands)

    Sachdeva, S.; Gravesteijn, Dirk J; Soccol, D.; Kapteijn, F.; Sudhölter, E.J.R.; Gascon, J.; Smet, de L.C.P.M.

    2016-01-01

    We report a simple method for sensor development using polymer-MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer. Sensing

  10. Ionic Self-Assembled Monolayer (ISAM) Nonlinear Optical Thin Films and Devices

    Science.gov (United States)

    1998-05-12

    elevated temperatures that is accompanied by a decreased film thickness. As the temperature is decreased water is reabsorbed , and the film swells to its...Vogtle, Supramolecular Chemistry; Wiley, New York, 1993. ISAM NLO Thin Films and Devices Final Report 28 [6] J. H. Fuhrhop and J. Koning, Membrane and

  11. Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

    Science.gov (United States)

    An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

    2015-02-01

    Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

  12. Calibration of EcoBadge Test-Strips for Ozone Measurement for GLOBE

    Science.gov (United States)

    Bush, Linda C.

    2003-01-01

    The majority of our work, therefore, centered on experiments at an extended exposure period at low ozone concentrations, creating and programming the necessary calibration curve into a Zikua reader. and verifying that the Zikua would use the curve reliably. Zikua is a device supplied by Vistanomics to 'read' the exposed EcoBadge cards and provide a read-out of measured ozone concentration in ppb. This device replaces the visual comparison to a calibrated color chart. For our initial studies, test papers were prepared by the usual method in small batches. Although testing would also eventually include Vistanomics' EcoBadge papers, we began with papers prepared in our lab so that we could be assured of the freshness of each batch. We felt this would allow us better comparison among our runs as we varied exposure time. At the outset, our target acceptable error was about +/- 10%. For example, if the actual ozone concentration was 20 ppb, then we hoped to be in the range 18-22 ppb. If the actual ozone concentration was 100 ppb. then we hoped to fall within 90-110 ppb in our measurements. Clearly a systematic error in the range of 3-4 ppb or more would significantly affect the lower exposure data.

  13. Fabrication and performance of pressure-sensing device consisting of electret film and organic semiconductor

    Science.gov (United States)

    Kodzasa, Takehito; Nobeshima, Daiki; Kuribara, Kazunori; Uemura, Sei; Yoshida, Manabu

    2017-04-01

    We propose a new concept of a pressure-sensitive device that consists of an organic electret film and an organic semiconductor. This device exhibits high sensitivity and selectivity against various types of pressure. The sensing mechanism of this device originates from a modulation of the electric conductivity of the organic semiconductor film induced by the interaction between the semiconductor film and the charged electret film placed face to face. It is expected that a complicated sensor array will be fabricated by using a roll-to-roll manufacturing system, because this device can be prepared by an all-printing and simple lamination process without high-level positional adjustment for printing processes. This also shows that this device with a simple structure is suitable for application to a highly flexible device array sheet for an Internet of Things (IoT) or wearable sensing system.

  14. Fundamentals of photoelectric effects in molecular electronic thin film devices: applications to bacteriorhodopsin-based devices.

    Science.gov (United States)

    Hong, F T

    1995-01-01

    This tutorial lecture focuses on the fundamental mechanistic aspects of light-induced charge movements in pigment-containing membranes. The topic is relevant to molecular electronics because many prototypes optoelectronic devices are configured as pigment-containing thin films. We use reconstituted bacteriorhodopsin membranes as an example to illustrate the underlying principle of measurements and data interpretation. Bacteriorhodopsin, a light-driven proton pump, is the only protein component in the purple membrane of Halobacterium halobium. It resembles the visual pigment rhodopsin chemically but performs the function of photosynthesis. Bacteriorhodopsin thus offers an unprecedented opportunity for us to compare the visual photoreceptor and the photosynthetic apparatus from a mechanistic point of view. Bacteriorhodopsin, well known for its exceptional chemical and mechanical stability, is also a popular advanced biomaterial for molecular device construction. The tutorial approaches the subject from two angles. First, the fundamental photoelectric properties are exploited for device construction. Second, basic design principles for photosensors and photon energy converters can be elucidated via 'reverse engineering'. The concept of molecular intelligence and the principle of biomimetic science are discussed.

  15. Symbolism and Psychological Realism in "The Red Badge of Courage."

    Science.gov (United States)

    McDermott, John J.

    1968-01-01

    In "The Red Badge of Courage," Stephen Crane overcomes serious artistic difficulties to depict a complicated psychological change in his protagonist, Henry Fleming, an unsophisticated and inarticulate farm boy. To embody the development of this protagonist, Crane uses a series of thematically-related incidents and a set of thematic…

  16. Open Badges: Novel Means to Motivate, Scaffold and Recognize Learning

    Science.gov (United States)

    Jovanovic, Jelena; Devedzic, Vladan

    2015-01-01

    This report is centered on the emerging concept and technology of Open Badges (OBs) that are offering novel means and practices of motivating, scaffolding, recognizing, and credentialing learning. OBs are closely associated with values such as openness and learners' agency, participatory learning and peer-learning communities. This report points…

  17. Open Badges: Novel Means to Motivate, Scaffold and Recognize Learning

    Science.gov (United States)

    Jovanovic, Jelena; Devedzic, Vladan

    2015-01-01

    This report is centered on the emerging concept and technology of Open Badges (OBs) that are offering novel means and practices of motivating, scaffolding, recognizing, and credentialing learning. OBs are closely associated with values such as openness and learners' agency, participatory learning and peer-learning communities. This report points…

  18. Device and method for measuring thermal conductivity of thin films

    Science.gov (United States)

    Amer, Tahani R. (Inventor); Subramanian, Chelakara (Inventor); Upchurch, Billy T. (Inventor); Alderfer, David W. (Inventor); Sealey, Bradley S. (Inventor); Burkett, Jr., Cecil G. (Inventor)

    2001-01-01

    A device and method are provided for measuring the thermal conductivity of rigid or flexible, homogeneous or heterogeneous, thin films between 50 .mu.m and 150 .mu.m thick with relative standard deviations of less than five percent. The specimen is sandwiched between like material, highly conductive upper and lower slabs. Each slab is instrumented with six thermocouples embedded within the slab and flush with their corresponding surfaces. A heat source heats the lower slab and a heat sink cools the upper slab. The heat sink also provides sufficient contact pressure onto the specimen. Testing is performed within a vacuum environment (bell-jar) between 10.sup.-3 to 10.sup.-6 Torr. An anti-radiant shield on the interior surface of the bell-jar is used to avoid radiation heat losses. Insulation is placed adjacent to the heat source and adjacent to the heat sink to prevent conduction losses. A temperature controlled water circulator circulates water from a constant temperature bath through the heat sink. Fourier's one-dimensional law of heat conduction is the governing equation. Data, including temperatures, are measured with a multi-channel data acquisition system. On-line computer processing is used for thermal conductivity calculations.

  19. Digital Badges for Teacher Mastery: An Exploratory Study of a Competency-Based Professional Development Badge System. CCT Reports

    Science.gov (United States)

    Diamond, James; Gonzalez, Pilar Carmina

    2014-01-01

    This study contributes knowledge about how a digital badge system integrated into an online, subject-matter-specific, and competency-based professional development (PD) program affected teachers' experiences with and perceptions of the program activities. The report presents findings from a one-year exploratory study of an online PD program, and…

  20. Thin film bismuth iron oxides useful for piezoelectric devices

    Energy Technology Data Exchange (ETDEWEB)

    Zeches, Robert J.; Martin, Lane W.; Ramesh, Ramamoorthy

    2016-05-31

    The present invention provides for a composition comprising a thin film of BiFeO.sub.3 having a thickness ranging from 20 nm to 300 nm, a first electrode in contact with the BiFeO.sub.3 thin film, and a second electrode in contact with the BiFeO.sub.3 thin film; wherein the first and second electrodes are in electrical communication. The composition is free or essentially free of lead (Pb). The BFO thin film is has the piezoelectric property of changing its volume and/or shape when an electric field is applied to the BFO thin film.

  1. Optical constants of electrochromic films and contrast ratio of reflective electrochromic devices.

    Science.gov (United States)

    Jaing, Cheng-Chung; Tang, Chien-Jen; Chan, Chih-Chao; Lee, Kun-Hsien; Kuo, Chien-Cheng; Chen, Hsi-Chao; Lee, Cheng-Chung

    2014-02-01

    This study investigates the optical constants of WO3 electrochromic films and NiO ion-storage films in bleached and colored states and that of a Ta2O5 film used as an ion conductor. These thin films were all prepared by electron-beam evaporation and characterized using a spectroscopic ellipsometer. The spectra obtained using a spectrophotometer and those calculated from the optical constants agreed closely. An all-solid thin-film reflective electrochromic device was fabricated and discussed. Its mean contrast ratio of reflectance in the range of 400-700 nm was 37.91.

  2. Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

    2014-02-04

    Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

  3. Basic Research of Vibration Energy Harvesting Micro Device using Vinylidene Fluoride / Trifluoroethylene Copolymer Thin Film

    Science.gov (United States)

    Takiguchi, T.; Sasaki, T.; Nakajima, T.; Yamaura, S.; Sekiguchi, T.; Shoji, S.

    2014-11-01

    Basic research of MEMS based micro devices for vibration energy harvesting using vinylidene fluoride / trifluoroethylene (VDF/TrFE) copolymer thin film was investigated. The VDF/TrFE copolymer thin film was formed by spin coating. Thickness of VDF/TrFE copolymer thin film was ranged from 375 nm to 2793 nm. Impedance of VDF/TrFE copolymer thin film was measured by LCR meter. Thin film in each thickness was fully poled by voltage based on C-V characteristics result. Generated power of the devices under applied vibration was observed by an oscilloscope. When the film thickness is 2793 nm, the generated power was about 0.815 μJ.

  4. Nanotube Film Electrode and an Electroactive Device Fabricated with the Nanotube Film Electrode and Methods for Making Same

    Science.gov (United States)

    Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor)

    2017-01-01

    Disclosed is a single wall carbon nanotube (SWCNT) film electrode (FE), all-organic electroactive device systems fabricated with the SWNT-FE, and methods for making same. The SWCNT can be replaced by other types of nanotubes. The SWCNT film can be obtained by filtering SWCNT solution onto the surface of an anodized alumina membrane. A freestanding flexible SWCNT film can be collected by breaking up this brittle membrane. The conductivity of this SWCNT film can advantageously be higher than 280 S/cm. An electroactive polymer (EAP) actuator layered with the SWNT-FE shows a higher electric field-induced strain than an EAP layered with metal electrodes because the flexible SWNT-FE relieves the restraint of the displacement of the polymeric active layer as compared to the metal electrode. In addition, if thin enough, the SWNT-FE is transparent in the visible light range, thus making it suitable for use in actuators used in optical devices.

  5. Structure of the Buried Metal-Molecule Interface in Organic Thin Film Devices

    DEFF Research Database (Denmark)

    Hansen, Christian Rein; Sørensen, Thomas Just; Glyvradal, Magni

    2009-01-01

    By use of specular X-ray reflectivity (XR) the structure of a metal-covered organic thin film device is measured with angstrom resolution. The model system is a Langmuir-Blodgett (LB) film, sandwiched between a silicon substrate and a top electrode consisting of 25 Å titanium and 100 Å aluminum...

  6. Growth and characterization of zinc oxide and PZT films for micromachined acoustic wave devices

    Science.gov (United States)

    Yoon, Sang Hoon

    The ability to detect the presence of low concentrations of harmful substances, such as biomolecular agents, warfare agents, and pathogen cells, in our environment and food chain would greatly advance our safety, provide more sensitive tools for medical diagnostics, and protect against terrorism. Acoustic wave (AW) devices have been widely studied for such applications due to several attractive properties, such as rapid response, reliability, portability, ease of use, and low cost. The principle of these sensors is based on a fundamental feature of the acoustic wave that is generated and detected by a piezoelectric material. The performance of the device, therefore, greatly depends on the properties of piezoelectric thin film. The required properties include a high piezoelectric coefficient and high electromechanical coefficients. The surface roughness and the mechanical properties, such as Young's modulus and hardness, are also factors that can affect the wave propagation of the device. Since the film properties are influenced by the structure of the material, understanding thin film structure is very important for the design of high-performance piezoelectric MEMS devices for biosensor applications. In this research, two piezoelectric thin film materials were fabricated and investigated. ZnO films were fabricated by CSD (Chemical Solution Deposition) and sputtering, and PZT films were fabricated by CSD only. The process parameters for solution derived ZnO and PZT films, such as the substrate type, the effect of the chelating agent, and heat treatment, were studied to find the relationship between process parameters and thin film structure. In the case of the sputtered ZnO films, the process gas types and their ratio, heat treatment in situ, and post deposition were investigated. The key results of systematic experiments show that the combined influence of chemical modifiers and substrates in chemical solution deposition have an effect on the crystallographic

  7. Buy badges and help finance Cap Loisirs activities!

    CERN Document Server

    2008-01-01

    Please give a warm welcome to Cap Loisirs’ volunteers who will be manning a stand at the main entrance on Friday 8 February! In honour of St. Valentine’s Day, they will be selling a selection of 5 badges designed by artist Anna Sommer, depicting declarations of love by our friends from the animal kingdom. Price : Frs. 3.- per badge The aim of Fondation Cap Loisirs is to provide leisure activities for mentally handicapped children, adolescents and adults. The Foundation offers a wide range of activities which allow the mentally handicapped to enjoy quality leisure in areas as varied as culture, sport, tourism, travel and artistic expression. Fondation Cap Loisirs Rue de Monthoux 66 – 1201 Geneva – Tel: 022 731 86 00 – CCP Genève 12-5587-5 – caploisirs@caploisirs.ch – http://www.Caploisirs.ch

  8. Damping MEMS Devices in Harsh Environments Using Active Thin Films

    Science.gov (United States)

    2008-06-17

    natural motion of domain walls and twin boundaries to absorb the energy. Therefore, the focus of this research is to develop new microscale damping...film is placed in tension the twin boundaries move and when the tension is released the residual stresses in the film produce a restoring force to move

  9. Tweeting badges: user motivations for displaying achievement in publicly networked environments.

    Science.gov (United States)

    Kwon, K Hazel; Halavais, Alexander; Havener, Shannon

    2015-02-01

    Badge systems, a common mechanism for gamification on social media platforms, provide a way for users to present their knowledge or experience to others. This study aims to contribute to the understanding of why social media users publicize their achievements in the form of online badges. Five motivational factors for badge display in public networked environments are distinguished-self-efficacy, social incentives, networked support, passing time, and inattentive sharing-and it is suggested that different badge types are associated with different motivations. System developers are advised to consider these components in their designs, applying the elements most appropriate to the communities they serve. Comparing user motivations associated with badges shared across boundaries provides a better understanding of how online badges relate to the larger social media ecosystem.

  10. Badges to Acknowledge Open Practices: A Simple, Low-Cost, Effective Method for Increasing Transparency.

    Science.gov (United States)

    Kidwell, Mallory C; Lazarević, Ljiljana B; Baranski, Erica; Hardwicke, Tom E; Piechowski, Sarah; Falkenberg, Lina-Sophia; Kennett, Curtis; Slowik, Agnieszka; Sonnleitner, Carina; Hess-Holden, Chelsey; Errington, Timothy M; Fiedler, Susann; Nosek, Brian A

    2016-05-01

    Beginning January 2014, Psychological Science gave authors the opportunity to signal open data and materials if they qualified for badges that accompanied published articles. Before badges, less than 3% of Psychological Science articles reported open data. After badges, 23% reported open data, with an accelerating trend; 39% reported open data in the first half of 2015, an increase of more than an order of magnitude from baseline. There was no change over time in the low rates of data sharing among comparison journals. Moreover, reporting openness does not guarantee openness. When badges were earned, reportedly available data were more likely to be actually available, correct, usable, and complete than when badges were not earned. Open materials also increased to a weaker degree, and there was more variability among comparison journals. Badges are simple, effective signals to promote open practices and improve preservation of data and materials by using independent repositories.

  11. Symbolic Images of Figures in The Red Badge of Courage

    Institute of Scientific and Technical Information of China (English)

    王晓俊

    2014-01-01

    Crane’s most well-known work, The Red Badge of Courage, is commonly believed to be the first great novel of the American Civil War, largely because of its vivid and detailed description of the experience of warfare. This paper conveys figure images symbolize that human life is insignificant in an indifferent universe in the novel, which are perfect symbolic images distin-guish Crane as a forerunner of modernistic writers.

  12. Incorporating Digital Badges and Ontology into Project-Based Learning

    OpenAIRE

    2014-01-01

    The rapid development of technology makes learning goals much more complex, diverse, and keeping changing. In reality, each product of design must be 'ultimately particular', which complicates the holistic learning objectives of a technology training class in the school setting, and, in turn, it runs the risk of becoming disconnected in the minds of learners and teachers. In order to address this issue, a solution named DBOPBL (Digital Badges, Ontology & Project Based Learning) is put forward...

  13. Photovoltaic devices created from electrodeposited nano-textured poly(thiophene) films

    Science.gov (United States)

    Jenkins, Judith L.; Ratcliff, Erin L.; Shallcross, R. Clayton; Head, Jeffrey L.; Armstrong, Neal R.

    2008-08-01

    Polythiophene films can be electrodeposited on modified ITO substrates, textured to increase their active surface area, doped to enhance charge transport, and then interfaced with C60 thin films to create "planar heterojunction" photovoltaic devices with power conversion efficiencies up to 1%. Preliminary results indicate that these electrodeposited films (e-P3HT) modified with appropriate ligands can serve as hosts for semi-conducting nanoparticles (CdSe NPs). These NPs may ultimately extend the device spectral sensitivity into the red and near-IR spectral regions.

  14. Transferred metal electrode films for large-area electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jin-Guo [Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Medical Drive, Singapore S117456 (Singapore); Kam, Fong-Yu [Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); Chua, Lay-Lay [Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore)

    2014-11-10

    The evaporation of metal-film gate electrodes for top-gate organic field-effect transistors (OFETs) limits the minimum thickness of the polymer gate dielectric to typically more than 300 nm due to deep hot metal atom penetration and damage of the dielectric. We show here that the self-release layer transfer method recently developed for high-quality graphene transfer is also capable of giving high-quality metal thin-film transfers to produce high-performance capacitors and OFETs with superior dielectric breakdown strength even for ultrathin polymer dielectric films. Dielectric breakdown strengths up to 5–6 MV cm{sup −1} have been obtained for 50-nm thin films of polystyrene and a cyclic olefin copolymer TOPAS{sup ®} (Zeon). High-quality OFETs with sub-10 V operational voltages have been obtained this way using conventional polymer dielectrics and a high-mobility polymer semiconductor poly[2,5-bis(3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene-2,5-diyl]. The transferred metal films can make reliable contacts without damaging ultrathin polymer films, self-assembled monolayers and graphene, which is not otherwise possible from evaporated or sputtered metal films.

  15. Improving light harvesting in polymer photodetector devices through nanoindented metal mask films

    NARCIS (Netherlands)

    Macedo, A. G.; Zanetti, F.; Mikowski, A.; Hummelen, J. C.; Lepienski, C. M.; da Luz, M. G. E.; Roman, L. S.

    2008-01-01

    To enhance light harvesting in organic photovoltaic devices, we propose the incorporation of a metal (aluminum) mask film in the system's usual layout. We fabricate devices in a sandwich geometry, where the mask (nanoindented with a periodic array of holes of sizes d and spacing s) is added between

  16. Crystalline Molybdenum Oxide Thin-Films for Application as Interfacial Layers in Optoelectronic Devices

    DEFF Research Database (Denmark)

    Fernandes Cauduro, André Luis; dos Reis, Roberto; Chen, Gong

    2017-01-01

    The ability to control the interfacial properties in metal-oxide thin films through surface defect engineering is vital to fine-tune their optoelectronic properties and thus their integration in novel optoelectronic devices. This is exemplified in photovoltaic devices based on organic, inorganic...

  17. Crystalline Molybdenum Oxide Thin-Films for Application as Interfacial Layers in Optoelectronic Devices

    DEFF Research Database (Denmark)

    Fernandes Cauduro, André Luis; dos Reis, Roberto; Chen, Gong

    2017-01-01

    The ability to control the interfacial properties in metal-oxide thin films through surface defect engineering is vital to fine-tune their optoelectronic properties and thus their integration in novel optoelectronic devices. This is exemplified in photovoltaic devices based on organic, inorganic...

  18. Ferroelectric Thin Films Basic Properties and Device Physics for Memory Applications

    CERN Document Server

    Okuyama, Masanori

    2005-01-01

    Ferroelectric thin films continue to attract much attention due to their developing, diverse applications in memory devices, FeRAM, infrared sensors, piezoelectric sensors and actuators. This book, aimed at students, researchers and developers, gives detailed information about the basic properties of these materials and the associated device physics. All authors are acknowledged experts in the field.

  19. Preparation of porous titanium oxide films onto indium tin oxide for application in organic photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, Andreia G. [Laboratorio de Dispositivos Nanoestruturados, Departamento de Fisica, Universidade Federal do Parana, Curitiba, Parana (Brazil); Mattos, Luana L.; Spada, Edna R.; Serpa, Rafael B.; Campos, Cristiani S. [Laboratorio de Sistemas Nanoestruturados, Departamento de Fisica, Universidade Federal de Santa Catarina, Florianopolis, Santa Catarina (Brazil); Grova, Isabel R.; Ackcelrud, Leni [Laboratorio de Polimeros Paulo Scarpa, Departamento de Quimica, Universidade Federal do Parana, Curitiba, Parana (Brazil); Reis, Francoise T.; Sartorelli, Maria L. [Laboratorio de Sistemas Nanoestruturados, Departamento de Fisica, Universidade Federal de Santa Catarina, Florianopolis, Santa Catarina (Brazil); Roman, Lucimara S., E-mail: lsroman@fisica.ufpr.br [Laboratorio de Dispositivos Nanoestruturados, Departamento de Fisica, Universidade Federal do Parana, Curitiba, Parana (Brazil)

    2012-05-01

    In this work, porous ordered TiO{sub 2} films were prepared through sol gel route by using a monolayer of polystyrene spheres as template on indium-tin oxide/glass substrate. These films were characterized by SEM, AFM, Raman spectroscopy, UV-vis absorbance and XRD. The UV-vis absorbance spectrum show a pseudo band gap (PBG) with maxima at 460 nm arising from the light scattering and partial or total suppression of the photon density of states, this PBG can be controlled by the size of the pore. We also propose the use of this porous film as electron acceptor electrode in organic photovoltaic cells; we show that devices prepared with porous titania displayed higher efficiencies than devices using compact titania films as electrode. Such behaviour was observed in both bilayer and bulk heterojunction devices.

  20. Flexible Surface Acoustic Wave Device with AlN Film on Polymer Substrate

    Directory of Open Access Journals (Sweden)

    Jian Zhou

    2012-01-01

    Full Text Available Surface acoustic wave device with c-axis-oriented aluminum nitride (AlN piezoelectric thin films on polymer substrates can be potentially used for development of flexible sensors, flexible microfluidic applications, microsystems, and lab-on-chip systems. In this work, the AlN films have been successfully deposited on polymer substrates using the DC reactive magnetron-sputtering method at room temperature, and the XRD, SEM, and AFM methods reveal that low deposition pressure is beneficial to the highly c-axis-oriented AlN film on polymer substrates. Studies toward the development of AlN thin film-based flexible surface acoustic wave devices on the polymer substrates are initiated and the experimental and simulated results demonstrate the devices showing the acoustic wave velocity of 9000–10000 m/s, which indicate the AlN lamb wave.

  1. An Exploratory Study of Undergraduate Nursing Students' Perceptions of Digital Badges.

    Science.gov (United States)

    Foli, Karen J; Karagory, Pamela; Kirby, Kristen

    2016-11-01

    Digital badges are virtual and visual representations of achievement by an individual learner. Student motivation to attain competencies in quality and safety may be increased through earning badges; however, empirical research in the literature is scarce. Approximately 100 nursing students' perceptions of digital badges were assessed after completing online safety and quality of care modules. The attention, relevance, confidence, and satisfaction (ARCS) model of motivation was used as a theoretical framework. Quantitative findings revealed a range of neutral to positive perceptions of digital badges. Content analysis described polarized opinions of the badges' effect on motivation toward learning; however, the majority of students found digital badges to be meaningful and motivating. Although most nursing students reported that digital badges motivated them in the learning activity, perceptions are contingent on factors that require further exploration: internal versus external motivation, previous exposure to badges, and future uses of digital badges in their professional lives. [J Nurs Educ. 2016;55(11):640-644.]. Copyright 2016, SLACK Incorporated.

  2. Adhesive flexible barrier film, method of forming same, and organic electronic device including same

    Science.gov (United States)

    Blizzard, John Donald; Weidner, William Kenneth

    2013-02-05

    An adhesive flexible barrier film comprises a substrate and a barrier layer disposed on the substrate. The barrier layer is formed from a barrier composition comprising an organosilicon compound. The adhesive flexible barrier film also comprises an adhesive layer disposed on the barrier layer and formed from an adhesive composition. A method of forming the adhesive flexible barrier film comprises the steps of disposing the barrier composition on the substrate to form the barrier layer, disposing the adhesive composition on the barrier layer to form the adhesive layer, and curing the barrier layer and the adhesive layer. The adhesive flexible barrier film may be utilized in organic electronic devices.

  3. Enhancement of high-TC superconducting thin film devices by nanoscale polishing

    Science.gov (United States)

    Michalowski, P.; Shapoval, T.; Meier, D.; Katzer, C.; Schmidl, F.; Schultz, L.; Seidel, P.

    2012-11-01

    The effects of mechanical nanoscale polishing on the superconducting parameters of YBa2Cu3O7-δ (YBCO) thin films and bi-crystal grain boundary Josephson junctions have been investigated. We prepared samples with additional gold nanocrystallites in the YBCO film. As they are distributed throughout the whole YBCO film, they provide a low-resistance ohmic contact even if parts of the film are removed. Polishing was performed either before or after the patterning and did not change the properties of the grain boundary. However, nanopolishing reduces the film roughness in a significant way, which makes it an indispensable tool for the preparation of integrated superconducting circuits. We also succeeded in tuning the IC and RN of the Josephson junctions of direct current superconducting quantum interference devices (dc-SQUIDs) by systematically reducing the film thickness, which opens up new possibilities in the application of magnetic field sensors.

  4. Clean graphene electrodes on organic thin-film devices via orthogonal fluorinated chemistry.

    Science.gov (United States)

    Beck, Jonathan H; Barton, Robert A; Cox, Marshall P; Alexandrou, Konstantinos; Petrone, Nicholas; Olivieri, Giorgia; Yang, Shyuan; Hone, James; Kymissis, Ioannis

    2015-04-08

    Graphene is a promising flexible, highly transparent, and elementally abundant electrode for organic electronics. Typical methods utilized to transfer large-area films of graphene synthesized by chemical vapor deposition on metal catalysts are not compatible with organic thin-films, limiting the integration of graphene into organic optoelectronic devices. This article describes a graphene transfer process onto chemically sensitive organic semiconductor thin-films. The process incorporates an elastomeric stamp with a fluorinated polymer release layer that can be removed, post-transfer, via a fluorinated solvent; neither fluorinated material adversely affects the organic semiconductor materials. We used Raman spectroscopy, atomic force microscopy, and scanning electron microscopy to show that chemical vapor deposition graphene can be successfully transferred without inducing defects in the graphene film. To demonstrate our transfer method's compatibility with organic semiconductors, we fabricate three classes of organic thin-film devices: graphene field effect transistors without additional cleaning processes, transparent organic light-emitting diodes, and transparent small-molecule organic photovoltaic devices. These experiments demonstrate the potential of hybrid graphene/organic devices in which graphene is deposited directly onto underlying organic thin-film structures.

  5. Processing and modeling issues for thin-film solar cell devices. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Birkmire, R.W.; Phillips, J.E. [Univ. of Delaware, Newark, DE (United States). Institute of Energy Conversion

    1997-11-01

    During the third phase of the subcontract, IEC researchers have continued to provide the thin film PV community with greater depth of understanding and insight into a wide variety of issues including: the deposition and characterization of CuIn{sub 1-x}Ga{sub x}Se{sub 2}, a-Si, CdTe, CdS, and TCO thin films; the relationships between film and device properties; and the processing and analysis of thin film PV devices. This has been achieved through the systematic investigation of all aspects of film and device production and through the analysis and quantification of the reaction chemistries involved in thin film deposition. This methodology has led to controlled fabrications of 15% efficient CuIn{sub 1-x}Ga{sub x}Se{sub 2} solar cells over a wide range of Ga compositions, improved process control of the fabrication of 10% efficient a-Si solar cells, and reliable and generally applicable procedures for both contacting and doping films. Additional accomplishments are listed below.

  6. Electrical contacts for a thin-film semiconductor device

    Science.gov (United States)

    Carlson, David E.; Dickson, Charles R.; D'Aiello, Robert V.

    1989-08-08

    A method of fabricating spaced-apart back contacts on a thin film of semiconductor material by forming strips of buffer material on top of the semiconductor material in locations corresponding to the desired dividing lines between back contacts, forming a film of metal substantially covering the semiconductor material and buffer strips, and scribing portions of the metal film overlying the buffer strips with a laser without contacting the underlying semiconductor material to separate the metal layer into a plurality of back contacts. The buffer material serves to protect the underlying semiconductor material from being damaged during the laser scribing. Back contacts and multi-cell photovoltaic modules incorporating such back contacts also are disclosed.

  7. Thermal annealing of arsenic tri-sulphide thin film and its influence on device performance

    Science.gov (United States)

    Choi, Duk-Yong; Madden, Steve; Bulla, Douglas; Wang, Rongping; Rode, Andrei; Luther-Davies, Barry

    2010-03-01

    Arsenic tri-sulphide (As2S3) thin film waveguides have been used successfully as nonlinear optical devices for all-optical signal processors. For such devices, low propagation loss is vital if high performance is to be obtained. In this study, thermal annealing was employed not only to stabilize the physical properties of the films, but also to reduce the sources of light attenuation in the as-deposited material. Here we investigated heat-induced changes to the microstructure and optical properties of As2S3 thin films and, based on this information, determined the best annealing conditions. The refractive index of the films rises with annealing due to thermal densification and increased heteropolar bond density. The growth of surface roughness and thermal stress in the film, however, limits the annealing temperature to ˜130 °C. We fabricated and analyzed waveguides produced from as-deposited and annealed films and found that the propagation loss of the guides dropped by ˜0.2 dB/cm as a result of appropriate annealing. Rayleigh scattering and absorption from defects associated with phase separation, homopolar bonds, voids, and dangling bonds in the as-deposited film are shown to contribute to the higher light attenuation in unannealed films.

  8. Combining the Converse Humidity/Resistance Response Behaviors of RGO Films for Flexible Logic Devices

    KAUST Repository

    Tai, Yanlong

    2017-03-23

    Carbon nanomaterials have excellent humidity sensing performance. Here, we demonstrate that reduced-graphene-oxide- (rGO) based conductive films with different thermal reduction times have gradient and invertible humidity/electrical resistance responses: rGO films (< 11 h, negative response, regarded as a signal of “0”), rGO films (around 11-13 h, balance point) and rGO films (> 13 h, negative response, regarded as a signal of “1”). We propose a new mechanism that describes a “scale”-like model for rGO films to explain these behaviors based on contributions from Ohm-contact resistance and capacitive reactance at interplate junctions, and intrinsic resistances of the nanoplates, respectively. This mechanism is accordingly validated via a series of experiments and electrical impedance spectroscopies, which complement more classical models based on proton conductivity. To explore the practical applications of the converse humidity/resistance responses, three simple flexible logic devices were developed, i) a rGO pattern for humidity-insensitive conductive film, which has the potential to greatly improve the stability of carbon-based electrical device to humidity; ii) a Janus pattern of rGO films for gesture recognition, which is very useful to human/machine interactions; iii) a sandwich pattern of rGO films for 3-dimensional (3D) noncontact sensing, which will be complementary to existing 3D touch technique.

  9. Recent progress on thin-film encapsulation technologies for organic electronic devices

    Science.gov (United States)

    Yu, Duan; Yang, Yong-Qiang; Chen, Zheng; Tao, Ye; Liu, Yun-Fei

    2016-03-01

    Among the advanced electronic devices, flexible organic electronic devices with rapid development are the most promising technologies to customers and industries. Organic thin films accommodate low-cost fabrication and can exploit diverse molecules in inexpensive plastic light emitting diodes, plastic solar cells, and even plastic lasers. These properties may ultimately enable organic materials for practical applications in industry. However, the stability of organic electronic devices still remains a big challenge, because of the difficulty in fabricating commercial products with flexibility. These organic materials can be protected using substrates and barriers such as glass and metal; however, this results in a rigid device and does not satisfy the applications demanding flexible devices. Plastic substrates and transparent flexible encapsulation barriers are other possible alternatives; however, these offer little protection to oxygen and water, thus rapidly degrading the devices. Thin-film encapsulation (TFE) technology is most effective in preventing water vapor and oxygen permeation into the flexible devices. Because of these (and other) reasons, there has been an intense interest in developing transparent barrier materials with much lower permeabilities, and their market is expected to reach over 550 million by 2025. In this study, the degradation mechanism of organic electronic devices is reviewed. To increase the stability of devices in air, several TFE technologies were applied to provide efficient barrier performance. In this review, the degradation mechanism of organic electronic devices, permeation rate measurement, traditional encapsulation technologies, and TFE technologies are presented.

  10. Thermoelastic stress analysis of multilayered films in a micro-thermoelectric cooling device

    Institute of Scientific and Technical Information of China (English)

    Yu-Mei Yang; Xing-Zhe Wang; Wen-Jie Zhang

    2012-01-01

    This paper presents an analytical solution for the thermoelastic stress in a typical in-plane's thin-film microthermoelectric cooling device under different operating conditions.The distributions of the permissible temperature fields in multilayered thin-films are analytically obtained,and the characteristics,including maximum temperature difference and maximum refrigerating output of the thermoelectric device,are discussed for two operating conditions.Analytical expressions of the thermoelastic stresses in the layered thermoelectric thin-films induced by the temperature difference are formulated based on the theory of multilayer system.The results demonstrate that,the geometric dimension is a significant factor which remarkably affects the thermoelastic stresses.The stress distributions in layers of semiconductor thermoelements,insulating and supporting membrane show distinctly different features.The present work may profitably guide the optimization design of highefficiency micro-thermoelectric cooling devices.

  11. Bendable ZnO thin film surface acoustic wave devices on polyethylene terephthalate substrate

    Science.gov (United States)

    He, Xingli; Guo, Hongwei; Chen, Jinkai; Wang, Wenbo; Xuan, Weipeng; Xu, Yang; Luo, Jikui

    2014-05-01

    Bendable surface acoustic wave (SAW) devices were fabricated using high quality c-axis orientation ZnO films deposited on flexible polyethylene terephthalate substrates at 120 °C. Dual resonance modes, namely, the zero order pseudo asymmetric (A0) and symmetric (S0) Lamb wave modes, have been obtained from the SAW devices. The SAW devices perform well even after repeated flexion up to 2500 μɛ for 100 times, demonstrating its suitability for flexible electronics application. The SAW devices are also highly sensitive to compressive and tensile strains, exhibiting excellent anti-strain deterioration property, thus, they are particularly suitable for sensing large strains.

  12. Recognising Informal Elearning with Digital Badging: Evidence for a Sustainable Business Model

    Science.gov (United States)

    Law, Patrina

    2015-01-01

    Digital badging as a trend in education is now recognised. It offers a way to reward and motivate, providing evidence of skills and achievements. Badged Open Courses (BOCs) were piloted by The Open University (OU) in 2013. The project built on research into the motivations and profiles of learners using free educational resources which the OU…

  13. Students' Perceptions of Digital Badges in a Public Library Management Course

    Science.gov (United States)

    Harmon, Jennifer; Copeland, Andrea

    2016-01-01

    For the Spring 2015 semester of the Public Library Management course, students were given digital badges along with grades for their coursework. For each topic's corresponding assignment, students received a traditional grade and those achieving at least an A- received a digital badge that represented the skill or knowledge demonstrated. By using…

  14. Fabricating thin-film photovoltaic devices using ultra-sonic spray-coating (Presentation Recording)

    Science.gov (United States)

    Lidzey, David G.

    2015-10-01

    The scale-up of thin-film electronic devices requires a manufacture tool set that is capable of fabricating thin films at high speed over large areas. One such technique capable of such a task is ultra-sonic spray coating. Here, a target solution is fed onto a vibrating tip that breaks the solution up into very fine droplets, with such droplets being carried to a surface by a gas stream. Such ultra-sonic coating processes are already widely used in Electronics, Medical and Displays industries to create films having excellent smoothness and homogeneity. In this talk, I describe the use of ultra-sonic spray-coating to deposit a range of materials for thin-film optoelectronics. As our spray-coating system operates in air, it was first necessary to explore the relative sensitivity of various conjugated polymer / fullerene blends to an air-based process route. It is found that carbazole based co-polymers are particularly stable, and can be processed in air (by spin-coating) into organic photovoltaic devices (OPV) without any apparent loss in device efficiency. I then show that spray-coating can be used to deposit a range of semiconductor materials into smooth, thin-films, including PEDOT:PSS, MoOx (from a precursor) and a series of polymer:fullerene blends. Using such a technique, we are able to scale up an array of devices having an area of 7 cm2, and using a PBDTTT-EFT:PC70BM blend, obtain OPVs having a power conversion efficiency (PCE) of 8.7%. I then discuss spray-coating as a method to fabricate photovoltaic devices based on CH3NH3PbI(3-x)Clx perovskite films. Here, by optimization of deposition parameters, devices are created having a PCE of 11.1%.

  15. Integrated Production of Ultra-Low Defect GaN Films and Devices for High-Power Amplifiers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High quality GaN epitaxial films are key to current efforts for development of both high-power/high-speed electronic devices and optoelectronic devices. In fact,...

  16. Integrated Production of Ultra-Low Defect GaN Films and Devices for High-Power Amplifiers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High quality GaN epitaxial films are one of the keys to current efforts for development of both high-power/high-speed electronic devices and optoelectronic devices....

  17. A new analytical model of high voltage silicon on insulator (SOI) thin film devices

    Institute of Scientific and Technical Information of China (English)

    Hu Sheng-Dong; Zhang Bo; Li Zhao-Ji

    2009-01-01

    A new analytical model of high voltage silicon on insulator (SOI) thin film devices is proposed, and a formula of silicon critical electric field is derived as a function of silicon film thickness by solving a 2D Poisson equation from an effective ionization rate, with a threshold energy taken into account for electron multiplying. Unlike a conventional silicon critical electric field that is constant and independent of silicon film thickness, the proposed silicon critical electric field increases sharply with silicon film thickness decreasing especially in the case of thin films, and can come to 141 V/μm at a film thickness of 0.1 μm which is much larger than the normal value of about 30 V/μm. From the proposed formula of silicon critical electric field, the expressions of dielectric layer electric field and vertical breakdown voltage (VB,V) are obtained. Based on the model, an ultra thin film can be used to enhance dielectric layer electric field and so increase vertical breakdown voltage for SOI devices because of its high silicon critical electric field, and with a dielectric layer thickness of 2 μm the vertical breakdown voltages reach 852 and 300V for the silicon film thicknesses of 0.1 and 5μm, respectively. In addition, a relation between dielectric layer thickness and silicon film thickness is obtained, indicating a minimum vertical breakdown voltage that should be avoided when an SOI device is designed. 2D simulated results and some experimental results are in good agreement with analytical results.

  18. Single crystal Fe1-xGax thin films for monolithic microwave devices

    Science.gov (United States)

    Kuanr, Bijoy K.; Camley, R. E.; Celinski, Z.; McClure, Adam; Idzerda, Yves

    2014-05-01

    Modern, high frequency, microwave devices for communications technologies can be made with thin ferromagnetic films with narrow microwave resonance linewidths. Recently, there has been interest in magnetostrictive materials where the material constants can change substantially with stresses and applied magnetic fields. We report the development of single crystal thin (20 nm thick) magnetostrictive films of Fe1-xGax (x = 0.20 FeGa(A), 0.23 FeGa(B), 0.28 FeGa(C) on GaAs(001) substrates and on their use in prototype microwave devices. These Galfenol films have a narrower linewidth than any previously reported similar thin films. We fabricate and characterize novel microstrip-based monolithic microwave devices using Galfenol thin films as an active element. We find a number of important features: (1) There is a large absorption (up to 30 dB/cm) at the resonance frequency. (2) The linewidth of the device is narrow ˜1.5 GHz. (3) The saturation magnetization of the samples decreases with the increase in Ga contents. (4) The cubic anisotropy is close to zero (˜0.06 kOe for FeGa(A)) and becomes negative for higher concentration of Ga content in the samples, and (5) the damping increases with increase in Ga concentration.

  19. Secondary treatment of films of colloidal quantum dots for optoelectronics and devices produced thereby

    Energy Technology Data Exchange (ETDEWEB)

    Semonin, Octavi Escala; Luther, Joseph M; Beard, Matthew C; Chen, Hsiang-Yu

    2014-04-01

    A method of forming an optoelectronic device. The method includes providing a deposition surface and contacting the deposition surface with a ligand exchange chemical and contacting the deposition surface with a quantum dot (QD) colloid. This initial process is repeated over one or more cycles to form an initial QD film on the deposition surface. The method further includes subsequently contacting the QD film with a secondary treatment chemical and optionally contacting the surface with additional QDs to form an enhanced QD layer exhibiting multiple exciton generation (MEG) upon absorption of high energy photons by the QD active layer. Devices having an enhanced QD active layer as described above are also disclosed.

  20. Pulsed laser deposition of silicon dioxide thin films with silicone targets for fabricating waveguide devices

    Science.gov (United States)

    Okoshi, Masayuki; Kuramatsu, Masaaki; Inoue, Narumi

    2002-06-01

    Silicon dioxide (SiO2) thin films were deposited at room temperature by 193-nm ArF excimer laser ablation of silicone in oxygen atmosphere. Only the side chains of the target were photo-dissociated during ablation to deposit Si-O bonds on a substrate in high laser fluence at about 10 J/cm2. Oxygen gas worked to oxidize the Si-O bonds ejected from the target to from SiO2 thin films at the gas pressure of 4.4 X 10-2 Torr, in addition to reducing the isolated carbon mixed into the films. We also found that the deposited rate could control refractive index of the films. The refractive index of the film deposited at 0.05 nm/pulse is greater than that of the film at 0.1 nm/pulse. Thus, a 0.2-micrometers thick SiO2 cladding film deposited at 0.1 nm/pulse was firstly formed on the whole surface of a 100- micrometers -thick polyester film, and then a 0.6 micrometers -thick SiO2 core film at 0.05 nm/pulse was fabricated in a line on the sample. The sample functioned as a waveguide device for a 633-nm line of He-Ne laser.

  1. Experiment and optimal design of a collection device for a residual plastic film baler

    Directory of Open Access Journals (Sweden)

    Qi NIU,Xuegeng CHEN,Chao JI,Jie WU

    2015-12-01

    Full Text Available It is imperative to carry out research on residual plastic film collection technology to solve the serious problem of farmland pollution. The residual plastic film baler was designed as a package for film strip collection, cleaning and baling. The collection device is a core component of the baler. Response surface analysis was used in this study to optimize the structure and working parameters for improving the collection efficiency of residual film and the impurity of film package. The results show that the factors affecting the collection rate of residual film and the impurity of the film package are the speed ratio (k between the trash removal roller and eccentric collection mechanism, the number (z and the mounting angle (θ of spring teeth in the same revolution plane. For the collection rate, the importance of the three factors are in the order, k>z>θ. Meanwhile, for the impurity, the importance of three factors are in the order, z>k>θ. When the speed ratio, the mounting angle and the number of spring teeth was set at 1.6º, 45º, and 8º, respectively, the collection rate of residual film was 88.9% and the impurity of residual film package was 14.2% for the baler.

  2. Nanopatterned Metallic Films for Use As Transparent Conductive Electrodes in Optoelectronic Devices

    KAUST Repository

    Catrysse, Peter B.

    2010-08-11

    We investigate the use of nanopatterned metallic films as transparent conductive electrodes in optoelectronic devices. We find that the physics of nanopatterned electrodes, which are often optically thin metallic films, differs from that of optically thick metallic films. We analyze the optical properties when performing a geometrical transformation that maintains the electrical properties. For one-dimensional patterns of metallic wires, the analysis favors tall and narrow wires. Our design principles remain valid for oblique incidence and readily carry over to two-dimensional patterns. © 2010 American Chemical Society.

  3. Electrical phase change of CVD-grown Ge-Sb-Te thin film device

    OpenAIRE

    Huang, C.C.; B. Gholipour; Ou, J.Y.; Knight, K.J.; Hewak, D. W.

    2011-01-01

    A prototype Ge-Sb-Te thin film phase-change memory device has been fabricated and reversible threshold and phase change switching demonstrated electrically, with a threshold voltage of 1.5 – 1.7 V. The Ge-Sb-Te thin film was fabricated by chemical vapour deposition (CVD) at atmospheric pressure using GeCl4, SbCl5, and Te precursors with reactive gas H2 at reaction temperature 780 °C and substrate temperature 250 °C. The surface morphology and composition of the CVD-grown Ge-Sb-Te thin film ha...

  4. Flexible barrier film, method of forming same, and organic electronic device including same

    Science.gov (United States)

    Blizzard, John; Tonge, James Steven; Weidner, William Kenneth

    2013-03-26

    A flexible barrier film has a thickness of from greater than zero to less than 5,000 nanometers and a water vapor transmission rate of no more than 1.times.10.sup.-2 g/m.sup.2/day at 22.degree. C. and 47% relative humidity. The flexible barrier film is formed from a composition, which comprises a multi-functional acrylate. The composition further comprises the reaction product of an alkoxy-functional organometallic compound and an alkoxy-functional organosilicon compound. A method of forming the flexible barrier film includes the steps of disposing the composition on a substrate and curing the composition to form the flexible barrier film. The flexible barrier film may be utilized in organic electronic devices.

  5. Optical meta-films of alumina nanowire arrays for solar evaporation and optoelectronic devices (Conference Presentation)

    Science.gov (United States)

    Kim, Kyoungsik; Bae, Kyuyoung; Kang, Gumin; Baek, Seunghwa

    2017-05-01

    Nanowires with metallic or dielectric materials have received considerable interest in many research fields for optical and optoelectronic devices. Metal nanowires have been extensively studied due to the high optical and electrical properties and dielectric nanowires are also investigated owing to the multiple scattering of light. In this research, we report optical meta-films of alumina nanowire arrays with nanometer scale diameters by fabrication method of self-aggregate process. The aluminum oxide nanowires are transparent from ultraviolet to near infrared wavelength regions and array structures have strong diffusive light scattering. We integrate those optical properties from the material and structure, and produce efficient an optical haze meta-film which has high transparency and transmission haze at the same time. The film enhances efficiencies of optical devices by applying on complete products, such as organic solar cells and LEDs, because of an expanded optical path length and light trapping in active layers maintaining high transparency. On the other hands, the meta-film also produces solar steam by sputtering metal on the aluminum oxide nanowire arrays. The nanowire array film with metal coating exhibits ultrabroadband light absorption from ultraviolet to mid-infrared range which is caused by nanofocusing of plasmons. The meta-film efficiently produces water steam under the solar light by metal-coated alumina arrays which have high light-to-heat conversion efficiency. The design, fabrication, and evaluation of our light management platforms and their applications of the meta-films will be introduced.

  6. Design and fabrication of a MEMS Lamb wave device based on ZnO thin film

    Energy Technology Data Exchange (ETDEWEB)

    Liu Mengwei; Li Junhong; Ma Jun; Wang Chenghao, E-mail: liumw@mail.ioa.ac.cn [Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-04-15

    This paper presents the design and fabrication of a Lamb wave device based on ZnO piezoelectric film. The Lamb waves were respectively launched and received by both Al interdigital transducers. In order to reduce the stress of the thin membrane, the ZnO/Al/LTO/Si{sub 3}N{sub 4}/Si multilayered thin plate was designed and fabricated. A novel method to obtain the piezoelectric constant of the ZnO film was used. The experimental results for characterizing the wave propagation modes and their frequencies of the Lamb wave device indicated that the measured center frequency of antisymmetric A{sub 0} and symmetric S{sub 0} modes Lamb wave agree with the theoretical predictions. The mass sensitivity of the MEMS Lamb wave device was also characterized for gravimetric sensing application. (semiconductor devices)

  7. The potential and device physics of interdigitated thin-film solar cells

    Science.gov (United States)

    Metzger, Wyatt K.

    2008-05-01

    The device physics of thin-film solar cells with interdigitated p-n junctions is examined for a range of spatial sizes, band offsets, and material parameters. The results are illustrated by focusing on recent nanoscale concepts for Cu(In,Ga)Se2 solar cells. Ideally, nanoscale interdigitated junctions can improve solar cell performance relative to planar-junction devices, and make reasonably high solar cell efficiencies (>15%) attainable even with mediocre electro-optical materials.

  8. Applications of HTSC films in hybrid optoelectronic devices

    Science.gov (United States)

    Pavuna, Davor

    1992-03-01

    An overview is given of potential applications of high-Tc superconductors (HTSC) in the context of hybrid optoelectronic technology. The main requirements are described for the in situ growth of epitaxial YBa2Cu3O(7-delta) (YBCO) films on SrTiO3 and discuss the properties of YBCO layers grown on Si and GaAs substrates with intermediate, conducting indium-tin-oxide buffer layers. The performances of the microbridge and the meander type of HTSC bolometer are compared, and several concepts are discussed that may become relevant for future hybrid optoelectronic technology.

  9. Transparent electrode of nanoscale metal film for optoelectronic devices

    Science.gov (United States)

    Lee, Illhwan; Lee, Jong-Lam

    2015-01-01

    This paper reviews the principles, impediments, and recent progress in the development of ultrathin flexible Ag electrodes for use in flexible optoelectronic devices. Thin Ag-based electrodes are promising candidates for next-generation flexible transparent electrodes. Thin Ag-based electrodes that have a microcavity structure show the best device performance, but have relatively low optical transmittance (OT) due to reflection and absorption of photons by the thin Ag; this trait causes problems such as spectral narrowing and change of emission color with viewing angle in white organic light-emitting diodes. Thinning the Ag electrode to overcome these problems. This ultrathin Ag electrode has a high OT, while providing comparable sheet resistance similar to indium tin oxide. As the OT of the electrode increases, the cavity is weakened, so the spectral width of the emission and the angular color stability are increased.

  10. Shrink-film microfluidic education modules: Complete devices within minutes.

    Science.gov (United States)

    Nguyen, Diep; McLane, Jolie; Lew, Valerie; Pegan, Jonathan; Khine, Michelle

    2011-06-01

    As advances in microfluidics continue to make contributions to diagnostics and life sciences, broader awareness of this expanding field becomes necessary. By leveraging low-cost microfabrication techniques that require no capital equipment or infrastructure, simple, accessible, and effective educational modules can be made available for a broad range of educational needs from middle school demonstrations to college laboratory classes. These modules demonstrate key microfluidic concepts such as diffusion and separation as well as "laboratory on-chip" applications including chemical reactions and biological assays. These modules are intended to provide an interdisciplinary hands-on experience, including chip design, fabrication of functional devices, and experiments at the microscale. Consequently, students will be able to conceptualize physics at small scales, gain experience in computer-aided design and microfabrication, and perform experiments-all in the context of addressing real-world challenges by making their own lab-on-chip devices.

  11. A Sandwiched/Cracked Flexible Film for Multi-Thermal Monitoring and Switching Devices

    KAUST Repository

    Tai, Yanlong

    2017-08-30

    Polydimethylsiloxane (PDMS)-based flexible films have substantiated advantages in various sensing applications. Here, we demonstrate the highly sensitive and programmable thermal-sensing capability (thermal index, B, up to 126 × 103 K) of flexible films with tunable sandwiched microstructures (PDMS/cracked single-walled carbon nanotube (SWCNT) film/PDMS) when a thermal stimulus is applied. We found that this excellent performance results from the following features of the film\\'s structural and material design: (1) the sandwiched structure allows the film to switch from a three-dimensional to a two-dimensional in-plane deformation and (2) the stiffness of the SWCNT film is decreased by introducing microcracks that make deformation easy and that promote the macroscopic piezoresistive behavior of SWCNT crack islands and the microscopic piezoresistive behavior of SWCNT bundles. The PDMS layer is characterized by a high coefficient of thermal expansion (α = 310 × 10-6 K-1) and low stiffness (∼2 MPa) that allow for greater flexibility and higher temperature sensitivity. We determined the efficacy of our sandwiched, cracked, flexible films in monitoring and switching flexible devices when subjected to various stimuli, including thermal conduction, thermal radiation, and light radiation.

  12. Photovoltaic material and device measurements workshop: focus on polycrystalline thin film cells

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-01-01

    The general purpose of the workshop was to accelerate the development of thin film solar cells by improving the versatility and reliability of material and device measurement techniques. Papers were presented under the following sessions: structural/chemical session; optical/electro-optical session; charge transport session; and poster session. Each paper was processed for EDB.

  13. Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting

    DEFF Research Database (Denmark)

    Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian

    2012-01-01

    We present a microelectromechanical system (MEMS) based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. Most piezoelectric energy harvesting devices use a cantilever beam of a non piezoelectric material as support beneath or in-between the piezoelectri...

  14. AlScN thin film based surface acoustic wave devices with enhanced microfluidic performance

    Science.gov (United States)

    Wang, W. B.; Fu, Y. Q.; Chen, J. J.; Xuan, W. P.; Chen, J. K.; Wang, X. Z.; Mayrhofer, P.; Duan, P. F.; Bittner, A.; Schmid, U.; Luo, J. K.

    2016-07-01

    This paper reports the characterization of scandium aluminum nitride (Al1-x Sc x N, x  =  27%) films and discusses surface acoustic wave (SAW) devices based on them. Both AlScN and AlN films were deposited on silicon by sputtering and possessed columnar microstructures with (0 0 0 2) crystal orientation. The AlScN/Si SAW devices showed improved electromechanical coupling coefficients (K 2, ~2%) compared with pure AlN films (droplets, and the acoustic streaming and pumping velocities were 2  ×  and 3  ×  those of the AlN/Si SAW devices, respectively. Mechanical characterization showed that the Young’s modulus and hardness of the AlN film decreased significantly when Sc was doped, and this was responsible for the decreased acoustic velocity and resonant frequency, and the increased temperature coefficient of frequency, of the AlScN SAW devices.

  15. Design of nanocomposite film-based plasmonic device for gas sensing

    Indian Academy of Sciences (India)

    Kaushik Brahmachari; Mina Ray

    2014-07-01

    Surface plasmon resonance (SPR) is a very efficient tool for chemical and biological sensing in nanotechnology, nanobiotechnology, medicine and environmental monitoring. A theoretical simulation study incorporating the use of admittance loci design methodology in SPR-based sensing device using gold-tungsten trioxide (Au-WO3−) nanocomposite film is reported in this paper. A simple Kretschmann–Raether-type prism-based plasmonic device consisting of a glass prism, Au-WO3− nanocomposite film and various gas samples is considered. Complex permittivity for both stoichiometric and non-stoichiometric Au-WO3− nanocomposite films has been used for the simulation of the admittance loci plots, resonance curves and sensitivity curves by considering angular interrogation at a fixed wavelength of 632.8 nm.

  16. The ion capturing effect of 5° SiOx alignment films in liquid crystal devices

    Science.gov (United States)

    Huang, Yi; Bos, Philip J.; Bhowmik, Achintya

    2010-09-01

    We show that SiOx, deposited at 5° to the interior surface of a liquid crystal cell allows for a surprisingly substantial reduction in the ion concentration of liquid crystal devices. We have investigated this effect and found that this type of film, due to its surface morphology, captures ions from the liquid crystal material. Ion adsorption on 5° SiOx film obeys the Langmuir isotherm. Experimental results shown allow estimation of the ion capturing capacity of these films to be more than an order of 10 000/μm2. These types of materials are useful for new types of very low power liquid crystal devices such as e-books.

  17. Lanthanide doped ceria thin films as possible counter electrode materials in electrochromic devices

    CERN Document Server

    Hartridge, A

    2000-01-01

    suitability of these thin films as counter electrodes in electrochromic devices. The final chapter then turns to the electrochemical insertion of lithium into these materials using cyclic voltammetry. All films studied enabled the reversible insertion of lithium with varying potentials and charge capacities without the loss of transmission of light common to other potential counter electrode materials. Certain compositions however, comprising ceria doped with Dy, Y, Nd and Pr, allowed enough lithium insertion (charge capacity) to fulfil the requirements of counter electrode materials in electrochromic devices. These materials are therefore worthy of further study. Crystalline solid solutions of lanthanide doped ceria have long been known for their high ionic conductivity and as such have found applications as oxygen sensors and in solid oxide fuel cells. With advances in preparative techniques over the years, thin films of ceria doped with zirconia and titania have been studied and found to possess the necess...

  18. Digital Badges for STEM Learning in Secondary Contexts: A Mixed Methods Study

    Science.gov (United States)

    Elkordy, Angela

    The deficit in STEM skills is a matter of concern for national economies and a major focus for educational policy makers. The development of Information and Communications Technologies (ICT) has resulted in a rapidly changing workforce of global scale. In addition, ICT have fostered the growth of digital and mobile technologies which have been the learning context, formal and informal, for a generation of youth. The purpose of this study was to design an intervention based upon a competency-based, digitally-mediated, learning intervention: digital badges for learning STEM habits of mind and practices. Designed purposefully, digital badge learning trajectories and criteria can be flexible tools for scaffolding, measuring, and communicating the acquisition of knowledge, skills, or competencies. One of the most often discussed attributes of digital badges, is the ability of badges to motivate learners. However, the research base to support this claim is in its infancy; there is little empirical evidence. A skills-based digital badge intervention was designed to demonstrate mastery learning in key, age-appropriate, STEM competencies aligned with Next Generation Science Standards (NGSS) and other educational standards. A mixed methods approach was used to study the impact of a digital badge intervention in the sample middle and high school population. Among the findings were statistically significant measures which substantiate that in this student population, the digital badges increased perceived competence and motivated learners to persist at task.

  19. Lanthanide doped ceria thin films as possible counter electrode materials in electrochromic devices

    Energy Technology Data Exchange (ETDEWEB)

    Hartridge, A

    2000-09-01

    Crystalline solid solutions of lanthanide doped ceria have long been known for their high ionic conductivity and as such have found applications as oxygen sensors and in solid oxide fuel cells. With advances in preparative techniques over the years, thin films of ceria doped with zirconia and titania have been studied and found to possess the necessary criteria to meet the requirements of counter electrode materials in solid state electrochromic devices. Existing preparative techniques however, have failed to produce thin films of lanthanide doped ceria for study of their optical and electrochemical properties. This thesis therefore presents in the first chapter, existing knowledge of these materials, a novel preparation technique developed as part of the thesis to prepare these materials as crystalline aqueous dispersions suitable for the preparation of quality thin films and the subsequent characterisation of sols and gels of these materials compared to the same materials prepared by conventional techniques. High-resolution transmission electron microscopy has also been used to assess the homogeneity of these nanocrystals on a nanoscale for the first time. The second chapter then discusses the optical properties of solids and thin films in general before using the crystalline sols produced in chapter 1 to fabricate thin films of these materials for the first time. The optical properties of these materials is then discussed in detail and the results show the optical suitability of these thin films as counter electrodes in electrochromic devices. The final chapter then turns to the electrochemical insertion of lithium into these materials using cyclic voltammetry. All films studied enabled the reversible insertion of lithium with varying potentials and charge capacities without the loss of transmission of light common to other potential counter electrode materials. Certain compositions however, comprising ceria doped with Dy, Y, Nd and Pr, allowed enough lithium

  20. Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Repins, Ingrid L.; Kuciauskas, Darius

    2015-07-07

    A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

  1. Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

    Science.gov (United States)

    Repins, Ingrid L.; Kuciauskas, Darius

    2015-07-07

    A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

  2. Degradation process in organic thin film devices fabricated using P3HT

    Indian Academy of Sciences (India)

    Rashmi; Ashok K Kapoor; Upendra Kumar; V R Balakrishnan; P K Basu

    2007-03-01

    The stability of regioregular poly(3-hexylthiophene 2,5-diyl) (P3HT) thin films sandwiched between indium tin oxide (ITO) and aluminium (Al) electrodes have been investigated under normal environmental conditions (25°C and RH ∼ 45-50%). Electrical and optical properties of ITO/P3HT/Al devices have been studied over a period of 30 days. Mobility of the order of 10-4 cm2/V-s has been obtained from the 2 law in the as- deposited P3HT films. Scanning electron microscopy (SEM) investigations show blistering of Al contacts in devices with a poly(3,4-ethylenedioxythiophene) (PEDOT) interlayer on application of voltage whereas no blistering is seen in devices without PEDOT. The results have been explained in terms of trap generation and propagation and the moisture-absorbing nature of PEDOT.

  3. Design and fabrication of a MEMS Lamb wave device based on ZnO thin film*

    Institute of Scientific and Technical Information of China (English)

    Liu Mengwei; Li Junhong; Ma Jun; Wang Chenghao

    2011-01-01

    This paper presents the design and fabrication of a Lamb wave device based on ZnO piezoelectric film.The Lamb waves were respectively launched and received by both Al interdigital transducers. In order to reduce the stress of the thin membrane, the ZnO/A1/LTO/Si3N4/Si multilayered thin plate was designed and fabricated. A novel method to obtain the piezoelectric constant of the ZnO film was used. The experimental results for characterizing the wave propagation modes and their frequencies of the Lamb wave device indicated that the measured center frequency of antisymmetric A0 and symmetric S0 modes Lamb wave agree with the theoretical predictions. The mass sensitivity of the MEMS Lamb wave device was also characterized for gravimetric sensing application.

  4. 25th anniversary article: carbon nanotube- and graphene-based transparent conductive films for optoelectronic devices.

    Science.gov (United States)

    Du, Jinhong; Pei, Songfeng; Ma, Laipeng; Cheng, Hui-Ming

    2014-04-02

    Carbon nanotube (CNT)- and graphene (G)-based transparent conductive films (TCFs) are two promising alternatives for commonly-used indium tin oxide-based TCFs for future flexible optoelectronic devices. This review comprehensively summarizes recent progress in the fabrication, properties, modification, patterning, and integration of CNT- and G-TCFs into optoelectronic devices. Their potential applications and challenges in optoelectronic devices, such as organic photovoltaic cells, organic light emitting diodes and touch panels, are discussed in detail. More importantly, their key characteristics and advantages for use in these devices are compared. Despite many challenges, CNT- and G-TCFs have demonstrated great potential in various optoelectronic devices and have already been used for some products like touch panels of smartphones. This illustrates the significant opportunities for the industrial use of CNTs and graphene, and hence pushes nanoscience and nanotechnology one step towards practical applications.

  5. Investigation of structural properties of chromium thin films prepared by a plasma focus device

    Science.gov (United States)

    Javadi, S.; Habibi, M.; Ghoranneviss, M.; Lee, S.; Saw, S. H.; Behbahani, R. A.

    2012-08-01

    We report the synthesis of chromium thin films on Si(400) substrates by utilizing a low-energy (1.6 kJ) plasma focus device. The films of chromium are deposited with different numbers of focus shots (15, 25 and 35) at a distance of 8 cm and at 0° angular position with respect to the anode axis. The films are investigated structurally by x-ray diffraction analysis and morphologically by atomic force microscopy and scanning electron microscopy. The elemental composition is characterized by energy dispersive x-ray analysis. Furthermore, Vicker's micro hardness is used to study the mechanical properties of the deposited films. The degree of crystallinity of chromium films, the size of the particles and the hardness values of the films increase when the number of focus shots is raised from 15 to 25 and then decrease when the substrate is treated with 35 shots. We discuss the dynamic processes involved in the formation of the chromium films.

  6. Finite-size scaling in silver nanowire films: design considerations for practical devices

    Science.gov (United States)

    Large, Matthew J.; Cann, Maria; Ogilvie, Sean P.; King, Alice A. K.; Jurewicz, Izabela; Dalton, Alan B.

    2016-07-01

    We report the first application of finite-size scaling theory to nanostructured percolating networks, using silver nanowire (AgNW) films as a model system for experiment and simulation. AgNWs have been shown to be a prime candidate for replacing Indium Tin Oxide (ITO) in applications such as capacitive touch sensing. While their performance as large area films is well-studied, the production of working devices involves patterning of the films to produce isolated electrode structures, which exhibit finite-size scaling when these features are sufficiently small. We demonstrate a generalised method for understanding this behaviour in practical rod percolation systems, such as AgNW films, and study the effect of systematic variation of the length distribution of the percolating material. We derive a design rule for the minimum viable feature size in a device pattern, relating it to parameters which can be derived from a transmittance-sheet resistance data series for the material in question. This understanding has direct implications for the industrial adoption of silver nanowire electrodes in applications where small features are required including single-layer capacitive touch sensors, LCD and OLED display panels.We report the first application of finite-size scaling theory to nanostructured percolating networks, using silver nanowire (AgNW) films as a model system for experiment and simulation. AgNWs have been shown to be a prime candidate for replacing Indium Tin Oxide (ITO) in applications such as capacitive touch sensing. While their performance as large area films is well-studied, the production of working devices involves patterning of the films to produce isolated electrode structures, which exhibit finite-size scaling when these features are sufficiently small. We demonstrate a generalised method for understanding this behaviour in practical rod percolation systems, such as AgNW films, and study the effect of systematic variation of the length distribution of

  7. Thin film design for advanced thermochromic smart radiator devices

    Institute of Scientific and Technical Information of China (English)

    Feng Yu-Dong; Wang Zhi-Min; Ma Ya-Li; Zhang Fu-Jia

    2007-01-01

    This paper describes the research on the materials and design methods for advanced smart radiator devices (SRDs) on large-area flexible substrates utilized on spacecraft. The functional material is thermochromic vanadium dioxide. The coating design of 3RD is similar to the design of broadband filter coatings in a mid-infrared region. The multilayer coatings have complex structures. Coating materials must be highly transparent in a required spectrum region and also mechanically robust enough to endure the influence from the rigorous environments of outer space. The number of layers must be very small, suitable for the deposition on large-area flexible substrates. All the coatings are designed initially based on optical calculation and practical experience, and then optimized by the TFCALC software. Several designs are described and compared with each other. The results show that the emittance variability of the designed SRDs is great than 400%, more advanced than the reported ones.

  8. Mesoporous nanocrystalline film architecture for capacitive storage devices

    Science.gov (United States)

    Dunn, Bruce S.; Tolbert, Sarah H.; Wang, John; Brezesinski, Torsten; Gruner, George

    2017-05-16

    A mesoporous, nanocrystalline, metal oxide construct particularly suited for capacitive energy storage that has an architecture with short diffusion path lengths and large surface areas and a method for production are provided. Energy density is substantially increased without compromising the capacitive charge storage kinetics and electrode demonstrates long term cycling stability. Charge storage devices with electrodes using the construct can use three different charge storage mechanisms immersed in an electrolyte: (1) cations can be stored in a thin double layer at the electrode/electrolyte interface (non-faradaic mechanism); (2) cations can interact with the bulk of an electroactive material which then undergoes a redox reaction or phase change, as in conventional batteries (faradaic mechanism); or (3) cations can electrochemically adsorb onto the surface of a material through charge transfer processes (faradaic mechanism).

  9. Blue and green organic light-emitting devices with various film thicknesses for color tuning

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Blue and green organic light-emitting devices with a structure of indium tin oxide (ITO)/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1 '-biphenyl-4,4'-diamine (NPB)/aluminum(Ⅲ) bis(2-methyl-8-quinolinato)4 -phenylphenolato (BAlq)/tris(8-hydroxyquinolate)-aluminum (Alq3)/Mg:Ag have been fabricated. Blue to green light emission has been achieved with the change of organic film thickness. Based on energy band diagram and charge carrier tunneling theory, it is concluded that the films of different thicknesses play a role as a color-tuning layer and the color-variable electroluminescence (EL) is ascribed to the modulation function within the charge carrier recombination zone. In the case of heterostructure devices with high performance, the observed EL spectra varies significantly with the thickness of organic films, which is resulted from the shift of recombination region site. It has not been hitherto indicated that the devices compose of identical components could be implemented to realize different color emission by changing the film thickness of functional layers.

  10. Organic Thin Film Devices for Displays and Lighting

    Science.gov (United States)

    Weiss, Oliver J.; Krause, Ralf; Paetzold, Ralph

    Organic materials can be used for fabrication of, e.g., electronic circuits, solar cells, light sensors, memory cells and light emitting diodes. Especially organic light emitting diodes (OLEDs) are increasingly attractive because of their huge market potential. The feasibility of efficient OLEDs was first shown in 1987 [3]. Only about ten years later the first product, a display for car radios, entered the market. Today monochrome and full colour OLED-displays can be found in many applications replacing established flat panel display technologies like TFT-LCDs. This substitution is a consequence of the outstanding attributes of OLED technology: Organic light emitting displays are self-emissive, thin, video capable and in addition they show a wide temperature operation range and allow a viewing angle of nearly 180 degree in conjunction with a low power consumption. As performance has steadily increased over the last years, today OLEDs are also under investigation as next generation light source. In contrast to inorganic LEDs, they can be built as flat 2-dimensional light sources that are lightweight, colour tunable, and potentially cheap. This will open up new degrees of freedom in design leading also to completely new applications. In this contribution we will have a brief view on the history of organic electroluminescent materials before we introduce the basic principles of OLEDs with a focus on the physical processes leading to light generation in thin organic films. Along with an overview of different concepts and technologies used to build OLEDs, the current status of OLED development will be illustrated. The last part focuses on the challenges that have to be overcome to enable a sustainable success in the display and lighting markets.

  11. Fabrication of thermally evaporated Al thin film on cylindrical PET monofilament for wearable computing devices

    Science.gov (United States)

    Liu, Yang; Kim, Eunju; Han, Jeong In

    2016-01-01

    During the initial development of wearable computing devices, the conductive fibers of Al thin film on cylindrical PET monofilament were fabricated by thermal evaporation. Their electrical current-voltage characteristics curves were excellent for incorporation into wearable devices such as fiber-based cylindrical capacitors or thin film transistors. Their surfaces were modified by UV exposure and dip coating of acryl or PVP to investigate the surface effect. The conductive fiber with PVP coating showed the best conductivities because the rough surface of the PET substrate transformed into a smooth surface. The conductivities of PET fiber with and without PVP were 6.81 × 103 Ω-1cm-1 and 5.62 × 103 Ω-1cm-1, respectively. In order to understand the deposition process of Al thin film on cylindrical PET, Al thin film on PET fiber was studied using SEM (Scanning Electron Microscope), conductivities and thickness measurements. Hillocks on the surface of conductive PET fibers were observed and investigated by AFM on the surface. Hillocks were formed and grown during Al thermal evaporation because of severe compressive strain and plastic deformation induced by large differences in thermal expansion between PET substrate and Al thin film. From the analysis of hillock size distribution, it turns out that hillocks grew not transversely but longitudinally. [Figure not available: see fulltext.

  12. Method for Fabricating Miniaturized NiTi Self-Expandable Thin Film Devices with Increased Radiopacity

    Science.gov (United States)

    Bechtold, Christoph; Lima de Miranda, Rodrigo; Chluba, Christoph; Zamponi, Christiane; Quandt, Eckhard

    2016-12-01

    Nitinol is the material of choice for many medical applications, in particular for minimally invasive implants due to its superelasticity and biocompatibility. However, NiTi has limited radiopacity which complicates positioning in the body. A common strategy to increase the radiopacity of NiTi devices is the addition of radiopaque markers by micro-riveting or micro-welding. The recent trend of miniaturizing medical devices, however, reduces their radiopacity further, and makes the addition of radiopaque markers to these miniaturized devices difficult. NiTi thin film technology has great potential to overcome such limitations and to fabricate new generations of miniaturized, self-expandable NiTi medical devices with additional functionalities, such as structured multilayer devices with increased radiopacity. For this purpose, we have produced superelastic thin film NiTi samples covered locally with Tantalum structures of different thickness and different shape. These multilayer devices were characterized regarding their mechanical and corrosion properties as well as their X-ray visibility. The superelastic behavior of the underlying NiTi layer is impeded by the Ta layer, and shows therefore a dependence on the Tantalum patterning geometry and thickness. No delamination was observed after mechanical and corrosion tests. The multilayers reveal excellent corrosion resistance, as well as a significant increase in radiopacity.

  13. Accelerated development of CuSbS2 thin film photovoltaic device prototypes

    Energy Technology Data Exchange (ETDEWEB)

    Welch, Adam W. [National Renewable Energy Laboratory, Golden CO 80401 USA; Colorado School of Mines, Golden CO USA; Baranowski, Lauryn L. [National Renewable Energy Laboratory, Golden CO 80401 USA; Colorado School of Mines, Golden CO USA; Zawadzki, Pawel [National Renewable Energy Laboratory, Golden CO 80401 USA; DeHart, Clay [National Renewable Energy Laboratory, Golden CO 80401 USA; Johnston, Steve [National Renewable Energy Laboratory, Golden CO 80401 USA; Lany, Stephan [National Renewable Energy Laboratory, Golden CO 80401 USA; Wolden, Colin A. [Colorado School of Mines, Golden CO USA; Zakutayev, Andriy [National Renewable Energy Laboratory, Golden CO 80401 USA

    2016-02-03

    Development of alternative thin film photovoltaic technologies is an important research topic because of the potential of low-cost, high-efficiency solar cells to produce terawatt levels of clean power. However, this development of unexplored yet promising absorbers can be hindered by complications that arise during solar cell fabrication. Here, a high-throughput combinatorial method is applied to accelerate development of photovoltaic devices, in this case, using the novel CuSbS2 absorber via a newly developed three-stage self-regulated growth process to control absorber purity and orientation. Photovoltaic performance of the absorber, using the typical substrate CuInxGa1 - xSe2 (CIGS) device architecture, is explored as a function of absorber quality and thickness using a variety of back contacts. This study yields CuSbS2 device prototypes with ~1% conversion efficiency, suggesting that the optimal CuSbS2 device fabrication parameters and contact selection criteria are quite different than for CIGS, despite the similarity of these two absorbers. The CuSbS2 device efficiency is at present limited by low short-circuit current because of bulk recombination related to defects, and a small open-circuit voltage because of a theoretically predicted cliff-type conduction band offset between CuSbS2 and CdS. Overall, these results illustrate both the potential and limits of combinatorial methods to accelerate the development of thin film photovoltaic devices using novel absorbers.

  14. Fabrication of 3D Microfluidic Devices by Thermal Bonding of Thin Poly(methyl methacrylate) Films

    KAUST Repository

    Perez, Paul

    2012-07-01

    The use of thin-film techniques for the fabrication of microfluidic devices has gained attention over the last decade, particularly for three-dimensional channel structures. The reasons for this include effective use of chip volume, mechanical flexibility, dead volume reduction, enhanced design capabilities, integration of passive elements, and scalability. Several fabrication techniques have been adapted for use on thin films: laser ablation and hot embossing are popular for channel fabrication, and lamination is widely used for channel enclosure. However, none of the previous studies have been able to achieve a strong bond that is reliable under moderate positive pressures. The present work aims to develop a thin-film process that provides design versatility, speed, channel profile homogeneity, and the reliability that others fail to achieve. The three building blocks of the proposed baseline were fifty-micron poly(methyl methacrylate) thin films as substrates, channel patterning by laser ablation, and device assembly by thermal-fusion bonding. Channel fabrication was characterized and tuned to produce the desired dimensions and surface roughness. Thermal bonding was performed using an adapted mechanical testing device and optimized to produce the maximum bonding strength without significant channel deformation. Bonding multilayered devices, incorporating conduction lines, and integrating various types of membranes as passive elements demonstrated the versatility of the process. Finally, this baseline was used to fabricate a droplet generator and a DNA detection chip based on micro-bead agglomeration. It was found that a combination of low laser power and scanning speed produced channel surfaces with better uniformity than those obtained with higher values. In addition, the implemented bonding technique provided the process with the most reliable bond strength reported, so far, for thin-film microfluidics. Overall, the present work proved to be versatile

  15. Correlation between propagation loss and silicon dioxide film properties for surface acoustic wave devices.

    Science.gov (United States)

    Matsuda, Satoru; Miura, Michio; Matsuda, Takashi; Ueda, Masanori; Satoh, Yoshio; Hashimoto, Ken-Ya

    2013-05-01

    The correlation between the propagation loss and SiO2 film properties has been studied for temperature-compensated SAW devices using the SiO2/LiNbO3 structure. The SAW devices were prepared under different deposition temperatures for SiO2 film. Although they possessed excellent temperature coefficient of elasticity characteristics, devices prepared at lower temperature showed lower Q-factors. The SiO2 films were also deposited on a Si substrate under the same deposition conditions used for the SAW device preparation. Optical characterization was performed with Fourier transform infrared spectroscopy (FT-IR), spectrometer measurement, and Raman spectroscopy. IR absorbance spectra were almost same in the FT-IR measurement. However, optical attenuation in the UV region decreased with the deposition temperature in the spectrometer measurement. The optical attenuation is caused by the increase of the extinction coefficient in the SiO2 layer, and its optical wavelength dependence indicated that observed excess attenuation is caused by Rayleigh scattering. The Raman scattering also decreased with the deposition temperature in the Raman spectroscopy. The scattering is caused by the distortion of the SiO2 network. These results indicate that the Rayleigh scattering caused by the distortion of the SiO2 network is the main contributor to the excess SAW propagation loss in this case.

  16. Dispersion-model-free determination of optical constants: application to materials for organic thin film devices.

    Science.gov (United States)

    Flämmich, Michael; Danz, Norbert; Michaelis, Dirk; Bräuer, Andreas; Gather, Malte C; Kremer, Jonas H-W M; Meerholz, Klaus

    2009-03-10

    We describe a method to determine the refractive index and extinction coefficient of thin film materials without prior knowledge of the film thickness and without the assumption of a dispersion model. A straightforward back calculation to the optical parameters can be performed starting from simple measurements of reflection and transmission spectra of a 100-250 nm thick supported film. The exact film thickness is found simultaneously by fulfilling the intrinsic demand of continuity of the refractive index as a function of wavelength. If both the layer and the substrate are homogeneous and isotropic media with plane and parallel interfaces, effects like surface roughness, scattering, or thickness inhomogeneities can be neglected. Then, the accuracy of the measurement is approximately 10(-2) and 10(-3) for the refractive index and the extinction coefficient, respectively. The error of the thin film thickness determination is well below 1 nm. Thus this technique is well suited to determine the input parameters for optical simulations of organic thin film devices, such as organic light-emitting diodes (OLEDs) or organic photovoltaic (OPV) cells. We apply the method to the electroluminescent polymer poly(2,5-dioctyl-p-phenylene vinylene) (PDO-PPV) and show its applicability by comparing the measured and calculated reflection and transmission spectra of OLED stacks with up to five layers.

  17. Deposition of Low Stress Silicon Nitride Thin Film and Its Application in Surface Micromachining Device Structures

    Directory of Open Access Journals (Sweden)

    Beirong Zheng

    2013-01-01

    Full Text Available Surface machining processes are responsible for creating microstructures that reside near the surfaces of a substrate and are characterized by the fabrication of micromechanical structures from deposited thin films. These films can be selectively removed to build three-dimensional structures whose functionality typically requires that they should be freed from the planar substrate. Silicon nitride thin film is one of these important materials. In this paper, by adjusting the SiH2Cl2/NH3 gaseous ratio, low stress silicon nitride (LS SiN is deposited by the low pressure chemical vapor deposition (LPCVD process. The internal stress generally in 135 MPa has been detected using an FLX-2320 film stress tester. Based on the wide application in surface micromachining devices, the mechanical properties of LS SiN are measured by nanoindentation, giving the value of Young’s modulus of 224 GPa and the hardness of 22.5 GPa, respectively. Dry etching and wet etching are utilized to fabricate the LS SiN thin film for structural layers. The etching rate compared with normal Si3N4 film by LPCVD is demonstrated for silicon chip manufacture.

  18. Monitoring of bisphenol-A-diglycidyl-ether (BADGE) in canned fish in oil.

    Science.gov (United States)

    Simoneau, C; Theobald, A; Hannaert, P; Roncari, P; Roncari, A; Rudolph, T; Anklam, E

    1999-05-01

    A survey at the European levels was initiated on the quantification of bisphenol-A-diglycidyl-ether (BADGE) in canned fish in oil in order to assess the exposure of BADGE. A total of 382 canned fish sample were collected from all 15 Member States and Switzerland and analysed for BADGE in fish. The fish was extracted first with hexane and reextracted with acetonitrile, followed by a membrane filtration and reverse phase HPLC analysis with fluorescence detection. The analysis of the fish showed that about 3% of the samples contained BADGE at a level above 1 mg/kg. The samples exceeding the limit by a larger margin were mostly from anchovy cans and cans manufactured in 1991-1995.

  19. Restorative effect of oxygen annealing on device performance in HfIZO thin-film transistors

    Directory of Open Access Journals (Sweden)

    Tae-Jun Ha

    2015-03-01

    Full Text Available Metal-oxide based thin-film transistors (oxide-TFTs are very promising for use in next generation electronics such as transparent displays requiring high switching and driving performance. In this study, we demonstrate an optimized process to secure excellent device performance with a favorable shift of the threshold voltage toward 0V in amorphous hafnium-indium-zinc-oxide (a-HfIZO TFTs by using post-treatment with oxygen annealing. This enhancement results from the improved interfacial characteristics between gate dielectric and semiconductor layers due to the reduction in the density of interfacial states related to oxygen vacancies afforded by oxygen annealing. The device statistics confirm the improvement in the device-to-device and run-to-run uniformity. We also report on the photo-induced stability in such oxide-TFTs against long-term UV irradiation, which is significant for transparent displays.

  20. Synthesis and characterization of thin film electroluminescent devices all-prepared by ultrasonic spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez, E.B. [Universidad Autónoma de la Ciudad de México, Calle Prolongación San Isidro Núm. 151, Col. San Lorenzo Tezonco, Iztapalapa 09790, D. F., México (Mexico); Bizarro, M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Coyoacán 04510, Distrito Federal, México (Mexico); Alonso, J.C., E-mail: alonso@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Coyoacán 04510, Distrito Federal, México (Mexico)

    2013-12-02

    Alternating current thin film electroluminescent devices have been fabricated using aluminum-doped zinc oxide (ZnO:Al) as transparent conducting layer, aluminum oxide (Al{sub 2}O{sub 3}) as insulating layers, and manganese-doped zinc sulfide (ZnS:Mn) as electroluminescent layer. All these films were deposited by the ultrasonic spray pyrolysis technique at the same temperature (450°) on glass substrates, forming a standard MISIM (metal–insulator–semiconductor–insulator–metal) configuration. The electroluminescence of MISIM devices with a total thickness of ∼ 1330 nm was investigated by applying a sinusoidal voltage with a frequency of 10 kHz. The devices showed orange-emission spectra centered at approximately 570 nm, characteristic of {sup 4}T{sub 1} → {sup 6}A{sub 1} radiative transitions of Mn{sup 2+} ions in the ZnS host, with a sharp intensity increase upon increasing the root mean square voltage above a threshold of 25 V and a rapid saturation for voltages higher than 38 V. The electroluminescent emission of these MISIM structures can be observed with the naked eye under ambient illumination. - Highlights: • Thin film electroluminescent devices were fabricated by ultrasonic spray pyrolysis at 450 °C. • The electroluminescent devices were fabricated on glass substrates. • ZnO:Al was used as transparent conductive layer. • ZnS:Mn and Al{sub 2}O{sub 3} were used as phosphor and insulating layers, respectively. • The electroluminescent devices have a low threshold operation voltage.

  1. Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting

    DEFF Research Database (Denmark)

    Xu, Ruichao; Lei, Anders; Christiansen, T.L.

    2011-01-01

    We present a MEMS-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. The most common piezoelectric energy harvesting devices utilize a cantilever beam of a non piezoelectric material as support beneath or in-between the piezoelectric material....... It provides mechanical support but it also reduces the power output. Our device replaces the support with another layer of the piezoelectric material, and with the absence of an inactive mechanical support all of the stresses induced by the vibrations will be harvested by the active piezoelectric elements....

  2. Liquid Density Sensing Using Resonant Flexural Plate Wave Device with Sol-Gel PZT Thin Films

    CERN Document Server

    Yu, Jyh-Cheng

    2008-01-01

    This paper presents the design, fabrication and preliminary experimental results of a flexure plate wave (FPW) resonator using sol-gel derived lead zirconate titanates (PZT) thin films. The resonator adopts a two-port structure with reflecting grates on the composite membrane of PZT and SiNx. The design of the reflecting grate is derived from a SAW resonator model using COM theory to produce a sharp resonant peak. The comparison between the mass and the viscosity effects from the theoretical expression illustrates the applications and the constraints of the proposed device in liquid sensing. Multiple coatings of sol-gel derived PZT films are adopted because of the cost advantage and the high electromechanical coupling effect over other piezoelectric films. The fabrication issues of the proposed material structure are addressed. Theoretical estimations of the mass and the viscosity effects are compared with the experimental results. The resonant frequency has a good linear correlation with the density of low v...

  3. SIMPLIFIED SCALING TRANSFORMATION FOR THE NUMERICAL SIMULATION OF MEMS DEVICES WITH THIN FILM STRUCTURES

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; LI Zhihong

    2008-01-01

    Thin film is a widely used structure in the present microelectromechanical systems (MEMS) and plays a vital role in many functional devices. However, the great size difference between the film's thickness and its planar dimensions makes it difficult to study the thin film performance numerically. In this work, a scaling transformation was presented to make the different dimensional sizes equivalent, and thereby, to improve the grid quality considerably. Two numerical experiments were studied to validate the present scaling transformation method. The numerical results indicated that the largest grid size difference can be decreased to one to two orders of magnitude by using the present scaling transformation, and the memory required by the numerical simulation, i.e., the total grid number, could be reduced by about two to three orders of magnitude, while the numerical accuracies with and without this scaling transformation were nearly the same.

  4. Electrophysical Properties of Ge-Sb-Te Thin Films for Phase Change Memory Devices

    Science.gov (United States)

    Lazarenko, P. I.; Kozyukhin, S. A.; Sherchenkov, A. A.; Babich, A. V.; Timoshenkov, S. P.; Gromov, D. G.; Zabolotskaya, A. V.; Kozik, V. V.

    2017-01-01

    In this work, we studied temperature dependences of the resistivity and current-voltage characteristics of amorphous thin films based on the materials of a Ge-Sb-Te system of compositions GeSb4Te7 (GST147), GeSb2Te4 (GST124), and Ge2Sb2Te5 (GST225) applied in the phase change memory devices. The effect of changes in the composition of thin films on the crystallization temperature, resistivity of films in amorphous and crystalline states, and on the activation energy of conductivity is determined. It is found that the peculiarity of these materials is the mechanism of two-channel conductivity where the contribution to the conductivity is made by charge carriers excited into localized states in the band tails and by carriers of the delocalized states in the valence band.

  5. Wide-Bandgap CIAS Thin-film Photovoltaics with Transparent Back Contacts for Next-Generation Single and Multijunction Devices

    Science.gov (United States)

    Woods, Lawrence M.; Kalla, Ajay; Gonzalez, Damian; Ribelin, Rosine

    2005-01-01

    Future spacecraft and high-altitude airship (HAA) technologies will require high array specific power (W/kg), which can be met using thin-film photovoltaics (PV) on lightweight and flexible substrates. It has been calculated that the thin-film array technology, including the array support structure, begins to exceed the specific power of crystalline multi-junction arrays when the thin-film device efficiencies begin to exceed 12%. Thin-film PV devices have other advantages in that they are more easily integrated into HAA s, and are projected to be much less costly than their crystalline PV counterparts. Furthermore, it is likely that only thin-film array technology will be able to meet device specific power requirements exceeding 1 kW/kg (photovoltaic and integrated substrate/blanket mass only). Of the various thin-film technologies, single junction and radiation resistant CuInSe2 (CIS) and associated alloys with gallium, aluminum and sulfur have achieved the highest levels of thin-film device performance, with the best efficiency, reaching 19.2% under AM1.5 illumination conditions and on thick glass substrates.(3) Thus, it is anticipated that single- and tandem-junction devices with flexible substrates and based on CIS and related alloys could achieve the highest levels of thin-film space and HAA solar array performance.

  6. Growing Uniform Graphene Disks and Films on Molten Glass for Heating Devices and Cell Culture.

    Science.gov (United States)

    Chen, Yubin; Sun, Jingyu; Gao, Junfeng; Du, Feng; Han, Qi; Nie, Yufeng; Chen, Zhaolong; Bachmatiuk, Alicja; Priydarshi, Manish Kr; Ma, Donglin; Song, Xiuju; Wu, Xiaosong; Xiong, Chunyang; Rümmeli, Mark H; Ding, Feng; Zhang, Yanfeng; Liu, Zhongfan

    2015-12-16

    The direct growth of uniform graphene disks and their continuous film is achieved by exploiting the molten state of glass. The use of molten glass enables highly uniform nucleation and an enhanced growth rate (tenfold) of graphene, as compared to those scenarios on commonly used insulating solids. The obtained graphene glasses show promising application potentials in daily-life scenarios such as smart heating devices and biocompatible cell-culture mediums.

  7. Thin-film encapsulation of organic electronic devices based on vacuum evaporated lithium fluoride as protective buffer layer

    Science.gov (United States)

    Peng, Yingquan; Ding, Sihan; Wen, Zhanwei; Xu, Sunan; Lv, Wenli; Xu, Ziqiang; Yang, Yuhuan; Wang, Ying; Wei, Yi; Tang, Ying

    2017-03-01

    Encapsulation is indispensable for organic thin-film electronic devices to ensure reliable operation and long-term stability. For thin-film encapsulating organic electronic devices, insulating polymers and inorganic metal oxides thin films are widely used. However, spin-coating of insulating polymers directly on organic electronic devices may destroy or introduce unwanted impurities in the underlying organic active layers. And also, sputtering of inorganic metal oxides may damage the underlying organic semiconductors. Here, we demonstrated that by utilizing vacuum evaporated lithium fluoride (LiF) as protective buffer layer, spin-coated insulating polymer polyvinyl alcohol (PVA), and sputtered inorganic material Er2O3, can be successfully applied for thin film encapsulation of copper phthalocyanine (CuPc)-based organic diodes. By encapsulating with LiF/PVA/LiF trilayer and LiF/Er2O3 bilayer films, the device lifetime improvements of 10 and 15 times can be achieved. These methods should be applicable for thin-film encapsulation of all kinds of organic electronic devices. Moisture-induced hole trapping, and Al top electrode oxidation are suggest to be the origins of current decay for the LiF/PVA/LiF trilayer and LiF/Er2O3 bilayer films encapsulated devices, respectively.

  8. Study of triisopropylsilyl pentacene thin film and its interfacial properties for device applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ke, E-mail: K.Wang@hqu.edu.cn; Chen, Ruofei; Zhuang, Fengjiang; Chen, Chuanwen; Su, Shaojian; Xiang, Yang

    2015-06-01

    Two-hundred-nanometer-thick 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS-Pentacene) films were formed on Si substrates by spin coating. The rms roughness of the spun dendrite-type films is ~ 40 nm, determined by atomic force microscopy. Ordered crystalline structures were revealed by x-ray diffraction measurement, and the dominated absorption band from the ordered structures was further confirmed by ultraviolet-visible spectroscopy. The current–voltage characteristics of the junctions formed using TIPS-Pentacene on n-type Si substrates show good rectifying behavior with rectification ratios over 100 at 1 V. In the heterojunctions, barrier heights of ~ 0.8 eV and ideality factors of ~ 2 were determined based on thermionic emission model. It shows that TIPS-Pentacene can work well with n-type Si to form Schottky-type rectifying devices. Capacitance–voltage measurement performed on the metal–insulator–semiconductor structure of TIPS-Pentacene on SiO{sub 2} shows obvious effects of accumulation and depletion in TIPS-Pentacene with bias. The maximum width of the depletion layer in TIPS-Pentacene is estimated to be 9.4 nm. - Highlights: • Ordered 6,13-bis (triisopropylsilylethynyl) (TIPS)-Pentacene films are formed on substrates. • TIPS-Pentacene films can work with n-type Si as Schottky-type rectifying devices. • TIPS-Pentacene/SiO{sub 2} show obvious effects of accumulation and depletion with bias.

  9. Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices

    Science.gov (United States)

    Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

    2016-11-01

    Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs.

  10. Sorbent coated glass wool fabric as a thin film microextraction device.

    Science.gov (United States)

    Riazi Kermani, Farhad; Pawliszyn, Janusz

    2012-11-06

    A new approach for thin film microextraction (TFME) with mixed-phase sorptive coating is presented. Carboxen/polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) TFME samplers were prepared using spin coating and glass wool fabric mesh as substrate. The samplers were easily tailored in size and shape by cutting tools. Good durability and flat-shape stability were observed during extraction, stirring in water, and thermal desorption. The latter characteristic obviates the need for an extra framed holder for rapid TFME and makes the samplers more robust and easier to deploy. The samplers combine the advantages of adsorptive solid-phase microextraction (SPME) and TFME, including one-step solvent-free extraction and preconcentration, direct thermal desorption, and enhanced sensitivity without sacrificing analysis time due to thin film geometry. The analytical performance of these new devices was demonstrated using water samples spiked with N-nitrosamines (NAs) as model compounds. Over an order of magnitude enhancement of extraction efficiencies was obtained for the model compounds compared with the SPME fibers of similar coatings and PDMS thin film membrane. The results of this study indicate that these novel thin film devices are promising for rapid and efficient microextraction of polar analytes in water.

  11. The dependences of electroluminescent characteristics of ZnS:Mn thin films upon their device parameters

    Science.gov (United States)

    Sasakura, Hiroshi; Kobayashi, Hiroshi; Tanaka, Shosaku; Mita, Juro; Tanaka, Toshihiko; Nakayama, Hirofumi

    1981-11-01

    The dependences of brightness, emission efficiency η, average electric field EA, conduction current JA, and emission lifetime τ upon the device parameters such as film thickness, substrate temperature during evaporation, and Mn concentration have been systematically investigated in ZnS:Mn thin-film electroluminescent devices. The value of η increases rapidly with film thicknesses below 3000 Å but EA decreases slowly. These results can be explained by the increase of the crystallinity of the ZnS:Mn films. The value of η increases with the Mn concentration and reaches its maximum at about 0.45 wt %. At above this Mn concentration, η and τ decrease rapidly, EA increases, and JA decreases slowly. These results may be attributed to a decrease of hot electron energy and/or an increase of the nonradiative transition probability of the excited Mn centers. The brightness-voltage (B-V) hysteresis characteristic is observed in this Mn concentration region. This memory effect is also discussed.

  12. Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices.

    Science.gov (United States)

    Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

    2016-11-22

    Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs.

  13. Polycrystalline thin film materials and devices. Final subcontract report, 16 January 1990--15 January 1993

    Energy Technology Data Exchange (ETDEWEB)

    Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E.; Yokimcus, T.A. [Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion

    1993-08-01

    This report describes results and conclusions of the final phase (III) of a three-year research program on polycrystalline thin-film heterojunction solar cells. The research consisted of the investigation of the relationships between processing, materials properties, and device performance. This relationship was quantified by device modeling and analysis. The analysis of thin-film polycrystalline heterojunction solar cells explains how minority-carrier recombination at the metallurgical interface and at grain boundaries can be greatly reduced by the proper doping of the window and absorber layers. Additional analysis and measurements show that the present solar cells are limited by the magnitude of the diode current, which appears to be caused by recombination in the space charge region. Developing an efficient commercial-scale process for fabricating large-area polycrystalline, thin-film solar cells from a research process requires a detailed understanding of the individual steps in making the solar cell, and their relationship to device performance and reliability. The complexities involved in characterizing a process are demonstrated with results from our research program on CuInSe{sub 2}, and CdTe processes.

  14. Nanomechanical characterization of multilayered thin film structures for digital micromirror devices

    Energy Technology Data Exchange (ETDEWEB)

    Wei Guohua; Bhushan, Bharat; Joshua Jacobs, S

    2004-08-15

    The digital micromirror device (DMD), used for digital projection displays, comprises a surface-micromachined array of up to 2.07 million aluminum micromirrors (14 {mu}m square and 15 {mu}m pitch), which switch forward and backward thousands of times per second using electrostatic attraction. The nanomechanical properties of the thin-film structures used are important to the performance of the DMD. In this paper, the nanomechanical characterization of the single and multilayered thin film structures, which are of interest in DMDs, is carried out. The hardness, Young's modulus and scratch resistance of TiN/Si, SiO{sub 2}/Si, Al alloy/Si, TiN/Al alloy/Si and SiO{sub 2}/TiN/Al alloy/Si thin-film structures were measured using nanoindentation and nanoscratch techniques, respectively. The residual (internal) stresses developed during the thin film growth were estimated by measuring the radius of curvature of the sample before and after deposition. To better understand the nanomechanical properties of these thin film materials, the surface and interface analysis of the samples were conducted using X-ray photoelectron spectroscopy. The nanomechanical properties of these materials are analyzed and the impact of these properties on micromirror performance is discussed.

  15. An anode with aluminum doped on zinc oxide thin films for organic light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Xu Denghui [Institute of Optoelectronic Technology, Key Laboratory of Information Storage and Display, Beijing Jiaotong University, Beijing 100044 (China); Deng Zhenbo [Institute of Optoelectronic Technology, Key Laboratory of Information Storage and Display, Beijing Jiaotong University, Beijing 100044 (China)]. E-mail: zbdeng@center.njtu.edu.cn; Xu Ying [Institute of Optoelectronic Technology, Key Laboratory of Information Storage and Display, Beijing Jiaotong University, Beijing 100044 (China); Xiao Jing [Institute of Optoelectronic Technology, Key Laboratory of Information Storage and Display, Beijing Jiaotong University, Beijing 100044 (China); Liang Chunjun [Institute of Optoelectronic Technology, Key Laboratory of Information Storage and Display, Beijing Jiaotong University, Beijing 100044 (China); Pei Zhiliang [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Sun Chao [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China)

    2005-10-10

    Doped zinc oxides are attractive alternative materials as transparent conducting electrode because they are nontoxic and inexpensive compared with indium tin oxide (ITO). Transparent conducting aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by DC reactive magnetron sputtering method. Films were deposited at a substrate temperature of 150-bar {sup o}C in 0.03 Pa of oxygen pressure. The electrical and optical properties of the film with the Al-doping amount of 2 wt% in the target were investigated. For the 300-nm thick AZO film deposited using a ZnO target with an Al content of 2 wt%, the lowest electrical resistivity was 4x10{sup -4}{omega}cm and the average transmission in the visible range 400-700 nm was more than 90%. The AZO film was used as an anode contact to fabricate organic light-emitting diodes. The device performance was measured and the current efficiency of 2.9 cd/A was measured at a current density of 100 mA/cm{sup 2}.

  16. TiNi-based films for elastocaloric microcooling— Fatigue life and device performance

    Science.gov (United States)

    Ossmer, H.; Chluba, C.; Kauffmann-Weiss, S.; Quandt, E.; Kohl, M.

    2016-06-01

    The global trend of miniaturization and concomitant increase of functionality in microelectronics, microoptics, and various other fields in microtechnology leads to an emerging demand for temperature control at small scales. In this realm, elastocaloric cooling is an interesting alternative to thermoelectrics due to the large latent heat and good down-scaling behavior. Here, we investigate the elastocaloric effect due to a stress-induced phase transformation in binary TiNi and quaternary TiNiCuCo films of 20 μm thickness produced by DC magnetron sputtering. The mesoscale mechanical and thermal performance, as well as the fatigue behavior are studied by uniaxial tensile tests combined with infrared thermography and digital image correlation measurements. Binary films exhibit strong features of fatigue, involving a transition from Lüders-like to homogeneous transformation behavior within three superelastic cycles. Quaternary films, in contrast, show stable Lüders-like transformation without any signs of degradation. The elastocaloric temperature change under adiabatic conditions is -15 K and -12 K for TiNi and TiNiCuCo films, respectively. First-of-its-kind heat pump demonstrators are developed that make use of out-of-plane deflection of film bridges. Owing to their large surface-to-volume ratio, the demonstrators reveal rapid heat transfer. The TiNiCuCo-based devices, for instance, generate a temperature difference of 3.5 K within 13 s. The coefficients of performance of the demonstrators are about 3.

  17. Functionalized Nano-Film Microchannel Plate: A Single High Aspect Ratio Device for High Resolution, Low Noise Astronomical Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is to apply proven nano-film technology to enable Microchannel plate (MCP) devices to be manufactured on a range of insulating substrates and...

  18. Functionalized Nano-Film Microchannel Plate: A Single High Aspect Ratio Device for High Resolution, Low Noise Astronomical Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Atomic layer deposited functional nano-film technology is used to manufacture Microchannel plate (MCP) devices capable of high gain / low ion feedback operation, on...

  19. The Effect of Achievement Badges on Students’ Behavior: An Empirical Study in a University-Level Computer Science Course

    Directory of Open Access Journals (Sweden)

    Lasse Hakulinen

    2015-02-01

    Full Text Available Achievement badges are a form of gamification that are used in an attempt to increase user engagement and motivation in various systems. A badge is typically a graphical icon that appears as a reward for the user after reaching an achievement but that has no practical value. In this study, we describe and evaluate the use of achievement badges in the ANONYMOUS online learning environment where students solve interactive, automatically assessed exercises in a Data Structures and Algorithms course throughout the semester. We conducted an experiment where the students (N=281 were randomly divided into a treatment and a control group, with and without achievement badges. Students in the treatment group were awarded achievement badges, for example, for solving exercises on the first attempt, doing exercises early, or solving all the exercises in a round with full points. Grading was the same for both groups, i.e. collecting badges did not affect the final grade, even though the exercise points themselves did. Students’ activity in ANONYMOUS was logged in order to find out whether the achievement badges had an effect on their behavior. We also collected numerical and open-ended feedback in order to find out students’ attitudes towards the badges. Our results show that achievement badges can be used to affect students’ behavior. Statistically significant differences were observed in the time used per exercise, number of sessions, total time, and normalized total number of badges. Furthermore, the majority of the students reported being motivated by the badges. Based on our findings, achievement badges seem to be a promising method to motivate students and to encourage desired study practices.

  20. Formation of single-walled carbon nanotube thin films enriched with semiconducting nanotubes and their application in photoelectrochemical devices.

    Science.gov (United States)

    Wei, Li; Tezuka, Noriyasu; Umeyama, Tomokazu; Imahori, Hiroshi; Chen, Yuan

    2011-04-01

    Single-walled carbon nanotube (SWCNT) thin films, containing a high-density of semiconducting nanotubes, were obtained by a gel-centrifugation method. The agarose gel concentration and centrifugation force were optimized to achieve high semiconducting and metallic nanotube separation efficiency at 0.1 wt% agarose gel and 18,000g. The thickness of SWCNT films can be precisely controlled from 65 to 260 nm with adjustable transparency. These SWCNT films were applied in photoelectrochemical devices. Photocurrents generated by semiconducting SWCNT enriched films are 15-35% higher than those by unsorted SWCNT films. This is because of reducing exciton recombination channels as a result of the removal of metallic nanotubes. Thinner films generate higher photocurrents because charge carriers have less chances going in metallic nanotubes for recombination, before they can reach electrodes. Developing more scalable and selective methods for high purity semiconducting SWCNTs is important to further improve the photocurrent generation efficiency by using SWCNT-based photoelectrochemical devices.

  1. Spectroscopic ellipsometry as a process control tool for manufacturing cadmium telluride thin film photovoltaic devices

    Science.gov (United States)

    Smith, Westcott P.

    In recent decades, there has been concern regarding the sustainability of fossil fuels. One of the more promising alternatives is Cadmium Telluride (CdTe) thin-film photovoltaic (PV) devices. Improved quality measurement techniques may aid in improving this existing technology. Spectroscopic ellipsometry (SE) is a common, non-destructive technique for measuring thin films in the silicon wafer industry. SE results have also been tied to properties believed to play a role in CdTe PV device efficiency. A study assessing the potential of SE for use as a quality measurement tool had not been previously reported. Samples of CdTe devices produced by both laboratory and industrial scale processes were measured by SE and Scanning Electron Microscopy (SEM). Mathematical models of the optical characteristics of the devices were developed and fit to SE data from multiple angles and locations on each sample. Basic statistical analysis was performed on results from the automated fits to provide an initial evaluation of SE as a quantitative quality measurement process. In all cases studied, automated SE models produced average stack thickness values within 10% of the values produced by SEM, and standard deviations for the top bulk layer thickness were less than 1% of the average values.

  2. Performance analysis of resistive switching devices based on BaTiO3 thin films

    Science.gov (United States)

    Samardzic, Natasa; Kojic, Tijana; Vukmirovic, Jelena; Tripkovic, Djordjije; Bajac, Branimir; Srdic, Vladimir; Stojanovic, Goran

    2016-03-01

    Resitive switching devices, memristors, have recenty attracted much attention due to promising performances and potential applications in the field of logic and memory devices. Here, we present thin film BaTiO3 based memristor fabricated using ink-jet printing technique. Active material is a single layer barium titanate film with thickness of ̴100 nm, sandwitched between metal electodes. Printing parameters were optimized aiming to achieve stable drop flow and uniform printed layer. Current-voltage characteristics show typical memristive behavior with pinched hysteresis loop crossed at the origin, with marked differences between High Resistive State (HRS) and Low Resistive State (LRS). Obtained resistive states are stable during numerous switching processes. The device also shows unipolar switching effect for negative voltage impulses. Variable voltage impulse amplitudes leads to the shifting of the energy levels of electode contacts resulting in changing of the overall current through the device. Structural charcterization have been performed using XRD analysis and SEM micrography. High-temperature current-voltage measurements combined with transport parameter analysis using Hall efect measurement system (HMS 3000) and Impedance Analyzer AC measurements allows deeper insigth into conduction mechanism of ferroelectric memristors.

  3. Development of alloy-film coated dispenser cathode for terahertz vacuum electron devices application

    Energy Technology Data Exchange (ETDEWEB)

    Barik, R.K.; Bera, A. [School of Electrical Engineering and Computer Science, Seoul National University, Seoul (Korea, Republic of); Raju, R.S. [Central Electronics Engineering Research Institute (CEERI), Rajasthan (India); Tanwar, A.K.; Baek, I.K.; Min, S.H.; Kwon, O.J.; Sattorov, M.A. [Department of Physics and Astronomy, Center for THz-Bio Application Systems, and Seoul-Teracom Inc., Seoul National University, Seoul (Korea, Republic of); Lee, K.W. [LIG Nex1, Seoul (Korea, Republic of); Park, G.-S., E-mail: gunsik@snu.ac.kr [School of Electrical Engineering and Computer Science, Seoul National University, Seoul (Korea, Republic of); Department of Physics and Astronomy, Center for THz-Bio Application Systems, and Seoul-Teracom Inc., Seoul National University, Seoul (Korea, Republic of); Advanced Institute of Convergence Technology, Suwon-si, Gyeonggi-do (Korea, Republic of)

    2013-07-01

    High power terahertz vacuum electron devices demand high current density and uniform emission dispenser cathode. It was found that the coating of noble metals e.g., Os, Ir, and Re on the surface of tungsten dispenser cathodes enhances the emission capabilities and uniformity. Hence metal coated cathode might be the best candidate for terahertz devices applications. In this study, ternary-alloy-film cathode (2Os:2Re:1 W) and Os coated cathode have been developed and the results are presented. The cathodes made out of this alloy coating showed 1.5 times higher emission and 0.02 eV emission uniformity as compared to those of simply Os coated cathodes which can be used in terahertz devices application.

  4. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    Energy Technology Data Exchange (ETDEWEB)

    Aïssa, B., E-mail: aissab@emt.inrs.ca [Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha (Qatar); Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada); Nedil, M. [Telebec Wireless Underground Communication Laboratory, UQAT, 675, 1ère Avenue, Val d' Or, Quebec J9P 1Y3 (Canada); Kroeger, J. [NanoIntegris & Raymor Nanotech, Raymor Industries Inc., 3765 La Vérendrye, Boisbriand, Quebec J7H 1R8 (Canada); Haddad, T. [Department of Mechanical Engineering, McGill University, Montreal, Quebec H3A 0B8 (Canada); Rosei, F. [Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada)

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  5. Ultrafast switching of an electrochromic device based on layered double hydroxide/Prussian blue multilayered films

    Science.gov (United States)

    Liu, Xiaoxi; Zhou, Awu; Dou, Yibo; Pan, Ting; Shao, Mingfei; Han, Jingbin; Wei, Min

    2015-10-01

    Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K+ ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH/PB)n-ITO/0.1 M KCl electrolyte/ITO sandwich structure displays superior response properties (0.91/1.21 s for coloration/bleaching), a comparable coloration efficiency (68 cm2 C-1) and satisfactory optical contrast (45% at 700 nm), in comparison with other inorganic material-based ECDs reported previously. Therefore, this work presents a facile and cost-effective strategy to immobilize electrochemically active nanoparticles in a 2D inorganic matrix for potential application in displays, smart windows and optoelectronic devices.Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K+ ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH

  6. Use of nanoporous columnar thin film in the wafer-level packaging of MEMS devices

    Science.gov (United States)

    Lee, Byung-Kee; Choi, Dong-Hoon; Yoon, Jun-Bo

    2010-04-01

    This paper presents a new packaging technology that uses a nanoporous columnar thin film to seal microelectromechanical system (MEMS) devices at the wafer level. In the proposed packaging process, the processing temperature is 350 °C. The process is relatively inexpensive compared to wafer level packaging processes, because the wafer-bonding step is eliminated and the die size is shrunk. In the suggested approach, a sputtered columnar thin film at room temperature forms vertical nanopores as etch holes, and an air cavity is formed by the removal of a sacrificial layer through the nanopores in the columnar membrane. Subsequent hermetic vacuum packaging of the cavity is achieved by depositing thin films over the membrane under low pressure. The hermeticity of the packaging was verified by using an optical surface morphology microscope to measure the deflection change of the sealing membrane before and after breaking of the vacuum through an interconnected membrane. The long-term hermeticity was monitored by measuring the maximum central deflection of the PECVD sealing layer over a period of 170 days. The precise pressure (0.7 Torr) and short-term (30 days) pressure change inside the cavity were measured by encapsulated Ni Pirani gauges, representing packaged freestanding MEMS devices.

  7. Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Farzana Aktar [Experimental Physics Division, Atomic Energy Centre, 4, Kazi Nazrul Islam Avenue, Dhaka-1000 (Bangladesh); Hossain, Mohammad Abul [Department of Chemistry, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Uchida, Koji; Tamura, Takahiro; Sugawa, Kosuke; Mochida, Tomoaki; Otsuki, Joe [College of Science and Technology, Nihon University, 1-8-14 Kanda Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Mohiuddin, Tariq [Department of Physics, College of Science, Sultan Qaboos University, Muscat (Oman); Boby, Monny Akter [Department of Physics, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Alam, Mohammad Sahabul, E-mail: msalam@ksu.edu.sa [Department of Physics, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Department of Chemical Engineering, College of Engineering & King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2015-10-15

    This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP) adorned graphene oxide (GO) nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR) radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW{sup −1}. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

  8. Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

    Directory of Open Access Journals (Sweden)

    Farzana Aktar Chowdhury

    2015-10-01

    Full Text Available This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP adorned graphene oxide (GO nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW−1. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

  9. Improving the Validity of Squeeze Film Air-Damping Model of MEMS Devices with Border Effect

    Directory of Open Access Journals (Sweden)

    Cheng Bai

    2014-01-01

    Full Text Available Evaluation of squeezed film air damping is critical in the design and control of dynamic MEMS devices. The published squeezed film air damping models are generally derived from the analytical solutions of Reynolds equation or its other modified forms under the supposition of trivial pressure boundary conditions on the peripheral borders. These treatments ignoring the border effect can not give faithful result for structure with smaller air venting gap or the double-gimbaled structure in which the inner frame and outer one affect the air venting. In this paper, we use Green’s function to solve the nonlinear Reynolds equation with inhomogeneous boundary conditions. For two typical normal motion cases of parallel plate, the analytical models of squeeze film damping force with border effect are established. The viscous and inertial losses with real values and image values acoustic impedance are all included in the model. These models reduced the time consumption while giving satisfactory result. Without multifield coupling analysis, the estimation of the dynamic behavior of MEMS device is also allowed, and the simulation of the system performance is more convenient.

  10. Magnetic shielding performance of superconducting YBCO thin film in a multilayer device structure

    Energy Technology Data Exchange (ETDEWEB)

    Uzun, Y., E-mail: uzunyigitcan@gmail.com; Avci, I.

    2014-12-15

    Highlights: • A multilayer structure was fabricated in the form of YBCO/STO/YBCO. • Bottom layer was used as a magnetic shield. • The top layer was patterned as a microbridge. • Magnetic shielding performance of the bottom layer onto the microbridge was tested. • I{sub c} of the microbridge was kept constant under the various magnetic fields. - Abstract: Magnetic shielding performance of superconducting YBaCu{sub 2}O{sub 7−x} (YBCO) thin film on an YBCO microbridge was analyzed in a multilayer structure. A sandwich type multilayer structure was fabricated onto a single crystal (1 0 0) SrTiO{sub 3} (STO) substrate in the form of YBCO/STO/YBCO by depositing a thin STO interlayer in between two YBCO layers. The top YBCO was patterned as 20 μm width meander-type microbridges and the bottom layer YBCO was used as magnetic shield. YBCO and STO thin films were deposited by dc and rf magnetron sputtering respectively, and the patterning was performed by using standard photolithography and wet etching. In order to enhance long-term stability of the final device, an additional STO thin film was deposited onto the device as an encapsulation layer. Electrical and magnetic characterizations of the YBCO thin film layers were carried out by means of ac magnetic susceptibility (χ–T) and resistance vs. temperature (R–T) measurements. The current–voltage (I–V) measurements were performed on the microbridges at 77 K by observing the shielding performance of the bottom YBCO layer under various applied magnetic fields. The results were compared with that of a same-type single layer YBCO device without a shielding layer. The zero field critical current value of the single layer 20 μm wide YBCO device was measured as 30 mA and decreased down to 20 mA as the field increased up to 100 mT. The same measurements on the multilayer device showed that the critical current values remained almost constant around 27 mA as the applied field increased.

  11. Electrochromics for smart windows: Oxide-based thin films and devices

    Energy Technology Data Exchange (ETDEWEB)

    Granqvist, Claes G.

    2014-08-01

    Electrochromic (EC) smart windows are able to vary their throughput of visible light and solar energy by the application of an electrical voltage and are able to provide energy efficiency and indoor comfort in buildings. Section 1 explains why this technology is important and timely by first outlining today's precarious situation concerning increasing energy use and associated effects on the world's climate, and this section also underscores the great importance of enhancing the energy efficiency of buildings by letting them function more in harmony with the environment—particularly its varying temperature—than is possible with current mainstream technologies. This same chapter also surveys recent work on the energy savings and other benefits that are possible with EC-based technologies. Section 2 then provides some notes on the history of the EC effect and its applications. Section 3 presents a generic design for the oxide-based EC devices that are most in focus for present-day applications and research. This design includes five superimposed layers with a centrally-positioned electrolyte connecting two oxide films—at least one of which having EC properties—and with transparent electrical conductors surrounding the three-layer structure in the middle. It is emphasized that this construction can be viewed as a thin-film electrical battery whose charging state is manifested as optical absorption. Also discussed are six well known hurdles for the implementation of these EC devices, as well as a number of practical constructions of EC-based smart windows. Section 4 is an in-depth discussion of various aspects of EC oxides. It begins with a literature survey for 2007–2013, which updates earlier reviews, and is followed by a general discussion of optical and electronic effects and, specifically, on charge transfer absorption in tungsten oxide. Ionic effects are then treated with foci on the inherent nanoporosity of the important EC oxides and on the

  12. Thin-Film Ferro Electric-Coupled Microstripline Phase Shifters With Reduced Device Hysteresis

    Science.gov (United States)

    Miranda, Felix A.; Romanofsky, Robert; Mueller, Carl H.; VanKeuls, Frederick

    2010-01-01

    This work deals with the performance of coupled microstripline phase shifters (CMPS) fabricated using BaxSr 1 -xTiO 3 (BST) ferroelectric thin films. The CMPS were fabricated using commercially available pulsed laser deposition BST films with Ba:Sr ratios of 30:70 and 20:80. Microwave characterization of these CMPS was performed at upper Kuband frequencies, particularly at frequencies near 16 and 18 GHz. X-ray diffraction studies indicate that the 30:70 films exhibit almost a 1:1 ratio between the in-plane and out-of-plane lattice parameters, suggesting that their cubics create strain -free films suitable for producing CMPS devices with reduced hysteresis in the paraelectric state. The quality of performance of the CMPS was studied based on their relative phase shift and insertion loss within the DC bias range of 0 to 400 V (i.e., E-field ranges within 0 to 53 V/micron). The performance of the CMPS was tested as a function of temperature to investigate their operation in the paraelectric, as well as in the ferroelectric, state (i.e., above and below the Curie temperature, respectively). The novel behavior discussed here is based on the experimental observation of the CMPS. This behavior, observed for the aforementioned cation ratio, highlights the relevance of good crystalline structure for high-quality CMPS.

  13. LOW POTENTIAL ELECTROPOLYMERIZATION OF ANISOTROPIC CONDUCTIVE POLYTHIOPHENE FILMS AND FABRICATION OF ELECTRICAL DEVICES

    Institute of Scientific and Technical Information of China (English)

    Xiao-bo Wan; Yun Lu; Xiao-rong Liu; Liang Zhou; Shi Jin; Qi Xue

    1999-01-01

    The complexation of thiophene with a Lewis acid with moderate acidity as a solvent, such as BF3-ethyl ether (BFEE) remarkedly lowered the electrochemical polymerization potential. The positively charged metal surface of electrode in the process of electrochemical deposition enhanced the coordination interaction between π-electrons of thiophene unit and the metal, which makes thiophene rings lie parallel to the surface of electrode, resulting in a highly ordered polymeric structure. Because of the large intra-chain transfer integrals, the transport of charge is believed to be principally along the conjugated chains, which is much greater than the inter-chain hopping. The specific electrical resistance across the polythiophene film thickness is more than 104 times than that along the surface plane of the film. In this paper we review the recent development of polymerization technique by low potential electrochemical method performed in our lab and several electrical devices in which the compact polythiophene films, such as anionic and cationic sieves, and laminate film junction ofundoped polythiophene derivatives were used.

  14. Polycrystalline thin film materials and devices. Annual subcontract report, 16 January 1991--15 January 1992

    Energy Technology Data Exchange (ETDEWEB)

    Baron, B.N.; Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E. [Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion

    1992-10-01

    Results of Phase II of a research program on polycrystalline thin film heterojunction solar cells are presented. Relations between processing, materials properties and device performance were studied. The analysis of these solar cells explains how minority carrier recombination at the interface and at grain boundaries can be reduced by doping of windows and absorber layers, such as in high efficiency CdTe and CuInSe{sub 2} based solar cells. The additional geometric dimension introduced by the polycrystallinity must be taken into consideration. The solar cells are limited by the diode current, caused by recombination in the space charge region. J-V characteristics of CuInSe{sub 2}/(CdZn)S cells were analyzed. Current-voltage and spectral response measurements were also made on high efficiency CdTe/CdS thin film solar cells prepared by vacuum evaporation. Cu-In bilayers were reacted with Se and H{sub 2}Se gas to form CuInSe{sub 2} films; the reaction pathways and the precursor were studied. Several approaches to fabrication of these thin film solar cells in a superstrate configuration were explored. A self-consistent picture of the effects of processing on the evolution of CdTe cells was developed.

  15. Fabrication of Thermoelectric Sensor and Cooling Devices Based on Elaborated Bismuth-Telluride Alloy Thin Films

    Directory of Open Access Journals (Sweden)

    Abdellah Boulouz

    2014-01-01

    Full Text Available The principal motivation of this work is the development and realization of smart cooling and sensors devices based on the elaborated and characterized semiconducting thermoelectric thin film materials. For the first time, the details design of our sensor and the principal results are published. Fabrication and characterization of Bi/Sb/Te (BST semiconducting thin films have been successfully investigated. The best values of Seebeck coefficient (α(T at room temperature for Bi2Te3, and (Bi1−xSbx2Te3 with x = 0.77 are found to be −220 µV/K and +240 µV/K, respectively. Fabrication and evaluation of performance devices are reported. 2.60°C of cooling of only one Peltier module device for an optimal current of Iopt=2.50 mA is obtained. The values of temperature measured by infrared camera, by simulation, and those measured by the integrated and external thermocouple are reported. A sensitivity of the sensors of 5 mV Torr−1 mW−1 for the pressure sensor has been found with a response time of about 600 ms.

  16. An easy way to measure accurately the direct magnetoelectric voltage coefficient of thin film devices

    Science.gov (United States)

    Poullain, Gilles; More-Chevalier, Joris; Cibert, Christophe; Bouregba, Rachid

    2017-01-01

    TbxDy1-xFe2/Pt/Pb(Zrx, Ti1-x)O3 thin films were grown on Pt/TiO2/SiO2/Si substrate by multi-target sputtering. The magnetoelectric voltage coefficient αΗΜΕ was determined at room temperature using a lock-in amplifier. By adding, in series in the circuit, a capacitor of the same value as that of the device under test, we were able to demonstrate that the magnetoelectric device behaves as a voltage source. Furthermore, a simple way to subtract the stray voltage arising from the flow of eddy currents in the measurement set-up, is proposed. This allows the easy and accurate determination of the true magnetoelectric voltage coefficient. A large αΗΜΕ of 8.3 V/cm. Oe was thus obtained for a Terfenol-D/Pt/PZT thin film device, without DC magnetic field nor mechanical resonance.

  17. Incoherent wavefront reconstruction by a retroemission device containing a thin fluorescent film: theory.

    Science.gov (United States)

    Rozova, Vlada S; Khaydukov, Eugenyi V; Zvyagin, Andrei V

    2016-07-20

    A retroemission device (REM) is an incoherent holographic device that represents a lenslet array situated on a substrate containing fluorescent material. Each lenslet focuses each wavelet of an optical wavefront incident on the REM device into a diffraction-limited volume (voxel) in the fluorescent material, so that the voxel coordinates encode the angle of incidence and curvature of the wavelet. The back-propagating fraction of the excited fluorescence is collected by the lenslet and quasi-collimated into a back-propagating wavelet. All wavelets are combined to reconstruct the incident wavefront propagating in the backward direction. We present a theoretical model of REM based on Fresnel-Kirchhoff approximation describing the reconstructed 3D image characteristics versus the thickness of the fluorescence film at the focal plane of the lenslets. Results of the computer simulations of the REM-based images of a point source, two axially separated point sources and an extended object (a circular rim) situated in the sagittal plane are presented. These results speak in favor of using a fluorescence film of minimum diffraction-limited thickness at the lenslet back focal plane. This REM structure minimizes the fluorescence background and improves the 3D imaging resolution in virtue of the exclusion of out-of-voxel fluorescence contributions to the reconstructed wavefront.

  18. Production of Inorganic Thin Scintillating Films for Ion Beam Monitoring Devices

    CERN Document Server

    Re, Maurizio; Cosentino, Luigi; Cuttone, Giacomo; Finocchiaro, Paolo; Hermanne, Alex; Lojacono, Pietro A; Ma, YingJun; Thienpont, Hugo; Van Erps, Jurgen; Vervaeke, Michael; Volckaerts, Bart; Vynck, Pedro

    2005-01-01

    In this work we present the development of beam monitoring devices consisting of thin CsI(Tl) films deposited on Aluminium support layers. The light emitted by the scintillating layer during the beam irradiation is measured by a CCD-camera. In a first prototype a thin Aluminium support layer of 6 micron allows the ion beam to easily pass through without significant energy loss and scattering effects. Therefore it turns out to be a non-destructive monitoring device to characterize on-line beam shape and beam position without interfering with the rest of the irradiation process. A second device consists of an Aluminium support layer which is thick enough to completely stop the impinging ions allowing to monitor at the same time the beam profile and the beam current intensity. Some samples have been coated by a 100 Å protective layer to prevent the film damage by atmosphere exposition. In this contribution we present our experimental results obtained by irradiating the samples with proton beams at 8.3 and 62 Me...

  19. Effects of diamond-like carbon thin film in organic light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Yap, Seong-Shan; Yong, Thian-Khok [Faculty of Engineering, Multimedia University, Cyberjaya, 63100 Selangor (Malaysia); Tou, Teck-Yong, E-mail: tytou@mmu.edu.m [Faculty of Engineering, Multimedia University, Cyberjaya, 63100 Selangor (Malaysia)

    2009-07-01

    Ultrathin diamond-like carbon (DLC) was deposited by pulsed Nd:YAG laserablation of graphite target on the indium tin oxide (ITO) surface that functioned as the buffered anode for single-layer organic light emitting devices (OLEDs). Deposited by 355 nm Nd:YAG laser, DLC films were characterized by the Raman spectroscopy and the bulk resistivity measurement. Insertion of DLC in the hole-transport ITO/DLC/TPD/Al device slightly increased the injection current density and reduced the turn-on voltage. But DLC insertion in the electron-transport ITO/DLC/Alq{sub 3}/Al device greatly decreased the injection current density and increased the turn-on voltage. For the ITO/DLC/(TPD + Alq{sub 3} + PVK)/Al device, that was doped with Alq{sub 3} and TPD, improved performance with a higher current density and brightness were consistently obtained. Possible mechanisms for the DLC effect in these single-layer devices were discussed.

  20. Chemically sensitive surface plasmon devices employing a self-assembled monolayer composite film

    Science.gov (United States)

    DePriest, J. C.; Meriaudeau, Fabrice; Oden, Patrick I.; Downey, Todd R.; Passian, A.; Wig, A. G.; Ferrell, Trinidad L.

    1998-12-01

    In this paper the results of detecting volatile organic compounds (VOC) employing surface plasmon-based sensors are presented. The initial step in preparing the sensing elements herein requires depositing Au degree(s) on a quartz slide. The sensing elements are based on either (1) freshly deposited Au degree(s) or (2) growth of a self assembled monolayer composite film (SAM) on to a freshly deposited Au degree(s) surface. The desired SAM is either (1) acid terminated using (omega) -mercaptoundecanoic acid (MUA-COOH) or (2) Cu2+ metal ion terminated yielding (omega) - mercaptoundecanoic acid-Cu2+ (MUA-Cu2+). The experimental apparatus shown here measures the reflectivity of the Au degree(s) surface as a function of time at a given angle. The response of this surface plasmon device to various VOC's is correlated to the composition of the SAM film.

  1. Influence of Parasitic Capacitance on Output Voltage for Series-Connected Thin-Film Piezoelectric Devices

    Directory of Open Access Journals (Sweden)

    Kensuke Kanda

    2012-12-01

    Full Text Available Series-connected thin film piezoelectric elements can generate large output voltages. The output voltage ideally is proportional to the number of connections. However, parasitic capacitances formed by the insulation layers and derived from peripheral circuitry degrade the output voltage. Conventional circuit models are not suitable for predicting the influence of the parasitic capacitance. Therefore we proposed the simplest model of piezoelectric elements to perform simulation program with integrated circuit emphasis (SPICE circuit simulations. The effects of the parasitic capacitances on the thin-film Pb(Zr, TiO3, (PZT elements connected in series on a SiO2 insulator are demonstrated. The results reveal the negative effect on the output voltage caused by the parasitic capacitances of the insulation layers. The design guidelines for the devices using series-connected piezoelectric elements are explained.

  2. Degradation and device physics modeling of SWCNT/CdTe thin film photovoltaics

    Science.gov (United States)

    Houshmand, Mohammad; Zandi, M. Hossein; Gorji, Nima E.

    2015-12-01

    We propose single walled carbon nanotubes as the n-type window partner of CdTe layer in a conventional CdS/CdTe thin film solar cells. The semiconductor nanotubes have superior optical and electrical properties i.e. controllable high band gap, being highly conductive and non-diffusive (not mobile). We modeled current-voltage characteristics of hybrid SWCNT/CdTe structure using Sah-Noyce-Shockley theory instead of Schottky barrier theory. The former theory is rather strong since it is based on carrier transport in the depletion region of a pn junction and considers the defect density within the depletion width. Also, a time dependent approach is used to simulate the degradation of device metrics under bias, illumination and temperature. It is discussed how a nanolayer can reduce the degradation rate of a thin film solar cell by surpassing grain boundaries and mobile ions migration towards junction.

  3. Immobilization of antibacterial chlorhexidine on stainless steel using crosslinking polydopamine film: Towards infection resistant medical devices.

    Science.gov (United States)

    Mohd Daud, Nurizzati; Saeful Bahri, Ihda Fithriyana; Nik Malek, Nik Ahmad Nizam; Hermawan, Hendra; Saidin, Syafiqah

    2016-09-01

    Chlorhexidine (CHX) is known for its high antibacterial substantivity and is suitable for use to bio-inert medical devices due to its long-term antibacterial efficacy. However, CHX molecules require a crosslinking film to be stably immobilized on bio-inert metal surfaces. Therefore, polydopamine (PDA) was utilized in this study to immobilize CHX on the surface of 316L type stainless steel (SS316L). The SS316L disks were pre-treated, modified with PDA film and immobilized with different concentrations of CHX (10mM-50mM). The disks were then subjected to various surface characterization analyses (ATR-FTIR, XPS, ToF-SIMS, SEM and contact angle measurement) and tested for their cytocompatibility with human skin fibroblast (HSF) cells and antibacterial activity against Escherichia coli and Staphylococcus aureus. The results demonstrated the formation of a thin PDA film on the SS316L surface, which acted as a crosslinking medium between the metal and CHX. CHX was immobilized via a reduction process that covalently linked the CHX molecules with the functional group of PDA. The immobilization of CHX increased the hydrophobicity of the disk surfaces. Despite this property, a low concentration of CHX optimized the viability of HSF cells without disrupting the morphology of adherent cells. The immobilized disks also demonstrated high antibacterial efficacy against both bacteria, even at a low concentration of CHX. This study demonstrates a strong beneficial effect of the crosslinked PDA film in immobilizing CHX on bio-inert metal, and these materials are applicable in medical devices. Specifically, the coating will restrain bacterial proliferation without suffocating nearby tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Electrochromic properties and performance of NiOx films and their corresponding all-thin-film flexible devices preparedby reactive DC magnetron sputtering

    Science.gov (United States)

    Dong, Dongmei; Wang, Wenwen; Dong, Guobo; Zhang, Fan; He, Yingchun; Yu, Hang; Liu, Famin; Wang, Mei; Diao, Xungang

    2016-10-01

    Nickel oxide (NiOx) thin films were deposited by direct current magnetron sputtering technique onto flexible substrates with various oxygen (O2) partial pressures. The influence of O2 contents during deposition process on film structure, morphology, composition, optical and electrochromic (EC) characteristics of the films were investigated. The EC response for nonstoichiometric NiOx films shows a strong dependence on grain size variations and surface morphology. Finally, the multiple-layer stacks ITO/NiOx/Ta2O5:H/WO3/ITO were sequentially vacuum deposited over flexible polyethylene terephthalate plates based on the optimization of NiOx single layers. A large optical contrast up to 60% and a good durability are obtained for full device. To perform preliminary research on the mechanical properties within flexible devices, we introduced nontrivial changes to the interfacial properties by replacing the glass with flexible polymers. The effects were studied through static bending and the nano-scratch test.

  5. Measurement of Thin Film Integrated Passive Devices on SiC through 500 C

    Science.gov (United States)

    Schwartz, Zachary D.; Ponchak, George E.; Alterovitz, Samuel A.; Downey, Alan N.; Chevalier, Christine T.

    2004-01-01

    Wireless communication in jet engines and high temperature industrial applications requires FD integrated circuits (RFICs) on wide bandgap semiconductors such as Silicon Carbide (SiC). In this paper, thin-film NiCr resistors, MIM capacitors, and spiral inductors are fabricated on a high purity semi-insulating 4H-SiC substrate. The devices are experimentally characterized through 50 GHz at temperatures of up to 500 C and the equivalent circuits are deembedded from the measured data. It is shown that the NiCr resistors are stable within 10% to 300 C while the capacitors have a value stable within 10% through 500 C.

  6. Electronic characterisation and computer modelling of thin film materials and devices for optoelectronic applications

    CERN Document Server

    Zollondz, J

    2001-01-01

    lock-in techniques. A comparison was made of the two-beam photogating experiment, with a single beam current-voltage measurement, which is also influenced by trapped space charge, as indicators of defect distributions. It was found that the photogating measurement is a more accurate indicator of the distribution of space charge, and hence defects, within a device. Application of the photogating effect in a colour detector is introduced and detector structure proposed. The simple structure and the thin film technique of a-Si:H deposition suggests the possibility of a low cost photodetector with high colour resolution. Double beam collection efficiency measurements have been carried out on hydrogenated amorphous silicon p-i-n devices. Apparent collection efficiencies higher than unity were observed, and explained by a process identified as photogating, in which a low intensity weakly absorbed probe beam modulates the photocurrent produced by a high intensity strongly absorbed bias beam. Computer simulations wer...

  7. Photo current generation in RGO - CdS nanorod thin film device

    Science.gov (United States)

    Chakraborty, Koushik; Chakrabarty, Sankalpita; Ibrahim, Sk.; Pal, Tanusri; Ghosh, Surajit

    2016-05-01

    Herein, we report the synthesis and characterization of reduced graphene oxide (RGO) - cadmium sulfide (CdS) nanocomposite materials. The reduction of GO, formation of CdS and decoration of CdS onto RGO sheets were done in a one- pot solvothermal process. We have observed that the PL intensity for CdS nanorods remarkably quenched after the attachment of RGO, which established the photo induced charge transformation from the CdS nanorod to RGO sheets through the RGO-CdS interface. The optoelectronic transport properties of our fabricated large area thin film device exhibits excellent photo induced charge generation under simulated solar light illumination. The photo sensitivity of the device increases linearly with the increase of illuminated light intensity. The RGO-CdS composite exhibits enhance photocatalytic dye degradation efficiency in compare to control CdS under simulated solar light illumination.

  8. Analysis of reaction products of food contaminants and ingredients: Bisphenol A diglycidyl ether (BADGE) in canned foods

    NARCIS (Netherlands)

    Coulier, L.; Bradley, E.L.; Bas, R.C.; Verhoeckx, K.C.M.; Driffield, M.; Harmer, N.; Castle, L.

    2010-01-01

    Bisphenol A diglycidyl ether (BADGE) is an epoxide that is used as a starting substance in the manufacture of can coatings for food-contact applications. Following migration from the can coating into food, BADGE levels decay and new reaction products are formed by reaction with food ingredients. The

  9. Relationship Between Absorber Layer Properties and Device Operation Modes For High Efficiency Thin Film Solar Cells

    Science.gov (United States)

    Ravichandran, Ram; Kokenyesi, Robert; Wager, John; Keszler, Douglas; CenterInverse Design Team

    2014-03-01

    A thin film solar cell (TFSC) can be differentiated into two distinct operation modes based on the transport mechanism. Current TFSCs predominantly exploit diffusion to extract photogenerated minority carriers. For efficient extraction, the absorber layer requires high carrier mobilities and long minority carrier lifetimes. Materials exhibiting a strong optical absorption onset near the fundamental band gap allows reduction of the absorber layer thickness to significantly less than 1 μm. In such a TFSC, a strong intrinsic electric field drives minority carrier extraction, resulting in drift-based transport. The basic device configuration utilized in this simulation study is a heterojunction TFSC with a p-type absorber layer. The diffusion/drift device operation modes are simulated by varying the thickness and carrier concentration of the absorber layer, and device performance between the two modes is compared. In addition, the relationship between device operation mode and transport properties, including carrier mobility and minority carrier lifetime are explored. Finally, candidate absorber materials that enable the advantages of a drift-based TFSC developed within the Center for Inverse Design are presented. School of Electrical Engineering and Computer Science.

  10. Properties of ZnS:Cu,Cl Thick Film Electroluminescent Devices by Screen Printing Method

    Energy Technology Data Exchange (ETDEWEB)

    Rho, J. S.; Yoo, S. H.; Chang, H. J. [Dankook University, Chonan (Korea)

    2001-06-01

    The ZnS:Cu,Cl thick film electroluminescent devices with the stacking type(separated with phosphors and insulator layers) and the composite type (mixed with phosphor and insulator materials) emission layers were fabricated on ITO/glass substrates by the screen printing methods. The optical and electrical properties were investigated as functions of applied voltages and frequencies. In the stacking type, the luminance was about 58 cd/m{sup 2} at the applied voltage of 400Hz, 200V and increased to 420 cd/m{sup 2} with increasing the frequency to 30Hz. For the composite type devices, the threshold voltage was 45V and the maximum luminance was 670 cd/m{sup 2} at the driving condition of 200V, 30Hz. The value of luminance of the composite type device showed 1.5 times higher than that of stacking type device. The main emission peak was 512 nm of bluish-green color at 1 Hz frequency below and shifted to 452 nm in the driving frequency over 5Hz showing the blue emission color. There were no distinct differences of the main emission peaks and color coordinate for both samples. (author). 13 refs., 8 figs.

  11. Levels of Cognitive Processes in a Non-Formal Science Education Program: Scouting's Science Merit Badges and the Revised Bloom's Taxonomy

    Science.gov (United States)

    Vick, Matthew; Garvey, Michael P.

    2011-01-01

    The United States Boy Scout merit badge program provides non-formal educational experiences for boys from ages 10-17. This study analyzes the objectives of the twenty-three science related merit badges using the lens of the revised Bloom's taxonomy. Merit badges requirements serve as objectives for this program. The verbs in the requirements were…

  12. Record mobility in transparent p-type tin monoxide films and devices by phase engineering

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso

    2013-06-25

    Here, we report the fabrication of nanoscale (15 nm) fully transparent p-type SnO thin film transistors (TFT) at temperatures as low as 180 C with record device performance. Specifically, by carefully controlling the process conditions, we have developed SnO thin films with a Hall mobility of 18.71 cm2 V-1 s-1 and fabricated TFT devices with a linear field-effect mobility of 6.75 cm2 V-1 s -1 and 5.87 cm2 V-1 s-1 on transparent rigid and translucent flexible substrates, respectively. These values of mobility are the highest reported to date for any p-type oxide processed at this low temperature. We further demonstrate that this high mobility is realized by careful phase engineering. Specifically, we show that phase-pure SnO is not necessarily the highest mobility phase; instead, well-controlled amounts of residual metallic tin are shown to substantially increase the hole mobility. A detailed phase stability map for physical vapor deposition of nanoscale SnO is constructed for the first time for this p-type oxide. © 2013 American Chemical Society.

  13. Electrochemical formation of tin oxide-hydroxide composite films for the application to electrochromic devices

    Science.gov (United States)

    Nishiyama, Kentaro; Matsuo, Ryo; Sasano, Junji; Yokoyama, Seiji; Izaki, Masanobu

    2017-07-01

    Liquid-state ion-storage layers which are commonly used for electrochromic devices (ECDs) have the problem of liquid leakage caused from mechanical damage or time degradation of sealing materials. To overcome this drawback, we tried to form Sn(O,H)x films comprising mixtures of tin oxide (SnO2) and tin hydroxide (Sn(OH)4) by electrodeposition in order to apply them to the solid-state ion-storage layers of solid-state ECDs. The Sn(O,H)x films were formed by anodic potentiostatic electrodeposition at 0.2 V vs. Ag/AgCl using 0.01 mol/L SnSO4 aqueous solution. Characterization of the samples with X-ray diffraction, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy revealed that they are composed of SnO2 and Sn(OH)4. Moreover, a coloring experiment of an ECD having a structure of FTO/ WO3(H2O)0.33/Sn(O,H)x/Cu was carried out under the application of a voltage, and it changed the color from pale yellow to blue in the coloring experiment. This result shows that the Sn(O,H)x films possesses the function as the solid-state ion-storage layers of solid-state ECDs.

  14. Comparison between different cost devices for digital capture of X-ray films: an image characteristics detection approach.

    Science.gov (United States)

    Salazar, Antonio José; Camacho, Juan Camilo; Aguirre, Diego Andrés

    2012-02-01

    A common teleradiology practice is digitizing films. The costs of specialized digitizers are very high, that is why there is a trend to use conventional scanners and digital cameras. Statistical clinical studies are required to determine the accuracy of these devices, which are very difficult to carry out. The purpose of this study was to compare three capture devices in terms of their capacity to detect several image characteristics. Spatial resolution, contrast, gray levels, and geometric deformation were compared for a specialized digitizer ICR (US$ 15,000), a conventional scanner UMAX (US$ 1,800), and a digital camera LUMIX (US$ 450, but require an additional support system and a light box for about US$ 400). Test patterns printed in films were used. The results detected gray levels lower than real values for all three devices; acceptable contrast and low geometric deformation with three devices. All three devices are appropriate solutions, but a digital camera requires more operator training and more settings.

  15. Magnetic field effect spectroscopy of C60-based films and devices

    Science.gov (United States)

    Gautam, Bhoj R.; Nguyen, Tho D.; Ehrenfreund, Eitan; Vardeny, Z. Valy

    2013-04-01

    We performed spectroscopy of the magnetic field effect (MFE) including magneto-photoinduced absorption (MPA) and magneto-photoluminescence (MPL) at steady state conditions in annealed and pristine fullerene C60 thin films, as well as magneto-conductance (MC) in organic diodes based on C60 interlayer. The hyperfine interaction has been shown to be the primary spin mixing mechanism for the MFE in the organics. In this respect, C60 is a unique material because 98.9% of the carbon atoms are 12C isotope, having spinless nucleus and thus lack hyperfine interaction. In spite of this, we obtained substantial MPA (up to ˜15%) and significant MC and MPL in C60 films and devices, and thus mechanisms other than the hyperfine interaction are responsible for the MFE in this material. Specifically, we found that the MFE(B) response is composed of narrow (˜10 mT) and broad (>100 mT) components. The narrow MFE(B) component is due to spin-dependent triplet exciton recombination in C60, which dominates the MPA(B) response at low pump intensities in films, or the MC response at small current densities in devices. In contrast, the broad MFE(B) component dominates the MPA(B) response at high pump intensities (or large current densities for MC(B)) and is attributed to spin mixing in the polaron pairs spin manifold due to g-factor mismatch between the electron- and hole-polarons in C60. Our results show that the organic MFE has a much broader scope than believed before.

  16. Deposition of Chromium Thin Films on Stainless Steel-304 Substrates Using a Low Energy Plasma Focus Device

    Science.gov (United States)

    Javadi, S.; Ghoranneviss, M.; Hojabri, A.; Habibi, M.; Hosseinnejad, M. T.

    2012-06-01

    In this paper, we study thin films of chromium deposited on stainless steel-304 substrates using a low energy (1.6 kJ) plasma focus device. The films of chromium are likewise deposited with 25 focus shots each at various axial distances from the top of the anode (3, 5, 7, 9 and 11 cm). We also consider different angular positions with respect to the anode axis (0°, 15° and 30°) at a distance of 5 cm from the anode tip to deposit the chromium films on the stainless steel substrates. To characterize the structural properties of the films, we benefit from X-ray diffraction (XRD) analysis. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are applied as well to study the surface morphology of these deposited films. Furthermore, we make use of Vicker's micro-hardness measurements to investigate the mechanical properties of chromium thin films. The XRD results show that the degree of crystallinity of chromium thin films depends on the substrate axial and angular positions. The AFM images illustrate that the film deposited at the distance of 5 cm and the angular position of 0° has quite a uniform surface with homogeneous distribution of grains on the film surface. From the hardness results, we observe that the sample deposited at the axial distance of 5 cm from the anode tip and at the angle of 0° with respect to the anode axis, is harder than the other deposited films.

  17. Glass-modified stress waves for adhesion measurement of ultra thin films for device applications

    Science.gov (United States)

    Gupta, Vijay; Kireev, Vassili; Tian, Jun; Yoshida, Hiroshi; Akahoshi, Haruo

    2003-08-01

    Laser-generated stress wave profiles with rarefaction shocks (almost zero post-peak decay times) have been uncovered in different types of glasses and presented in this communication. The rise time of the pulses was found to increase with their amplitude, with values reaching as high as 50 ns. This is in contrast to measurements in other brittle crystalline solids where pulses with rise times of 1 -2 ns and post-peak decay times of 16 -20 ns were recorded. The formation of rarefaction shock is attributed to the increased compressibility of glasses with increasing pressures. This was demonstrated using a one-dimensional nonlinear elastic wave propagation model in which the wave speed was taken as a function of particle velocity. The technological importance of these pulses in measuring the tensile strength of very thin film interfaces is demonstrated by using a previously developed laser spallation experiment in which a laser-generated compressive stress pulse in the substrate reflects into a tensile wave from the free surface of the film and pries off its interface at a threshold amplitude. Because of the rarefaction shock, glass-modified waves allow generation of substantially higher interfacial tensile stress amplitudes compared with those with finite post-peak decay profiles. Thus, for the first time, tensile strengths of very strong and ultra thin film interfaces can be measured. Results presented here indicate that interfaces of 185-nm-thick films, and with strengths as high as 2.7 GPa, can be measured. Thus, an important advance has been made that should allow material optimization of ultra thin layer systems that may form the basis of future MEMS-based microelectronic, mechanical and clinical devices.

  18. Preparation of nano-polycrystalline WO3 thin films and their solid-state electrochromic display devices.

    Science.gov (United States)

    Luo, Jianyi; Zeng, Qingguang; Long, Yongbing; Wang, Yi

    2013-02-01

    In this paper, nano-polycrystalline WO3 thin films with the thickness in the range of 100-200 nm have been uniformly prepared on the designed regions of ITO (indium tin oxide) glass substrates by thermal evaporation deposition. Their crystal structures, surface morphologies and uniformities are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. The solid-state electrochromic display (ECD) devices based on these nano-polycrystalline WO3 thin films have been also fabricated and have demonstrated to have better performance than normal thin films, including shorter response time, higher contrast, and furthermore, higher stability to keep the colored state without power consumption. These results demonstrate nano-polycrystalline WO3 thin films can be applied to improve the performance of ECD devices, especially suitable to static display.

  19. A low-power all-optical bistable device based on a liquid crystal layer embedded in thin gold films

    Science.gov (United States)

    Takase, Yuki; Tien Thanh, Pham; Fujimura, Ryushi; Kajikawa, Kotaro

    2014-04-01

    An all-optical bistable (AOB) resonator device composed of a 430-nm-thick liquid crystal (LC) layer embedded in two thin gold films (MLM) is reported in this paper. This device allows the use of the incident illumination at normal incidence, whereas the previous AOB devices based on twisted nematic (TN)-LC function only for illumination at oblique incidence. The fastest switching time was measured to be 1.8 ms, which is significantly faster than that of TN-LC. Because the MLM device operates free from electronic circuits, it is promising for two-dimensional optical data processing, random access optical memories, and spatial light modulators.

  20. High efficiency polarization-sensitive photovoltaic devices using oriented organic thin film

    Science.gov (United States)

    Tanaka, Hideyuki; Yasuda, Takeshi; Fujita, Katsuhiko; Tsutsui, Tetsuo

    2005-10-01

    We report the fabrication of polarization-sensitive photovoltaic devices made of hetero-junction type vacuum-sublimed multilayer films composed of aligned 3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (aligned-PTCBI) and titanyl phthalocyanine (TiOPc). The PTCBI layer was successfully made to be well aligned without losing high photovoltaic power-conversion efficiency. High polarization sensitivity was achieved at around 540 nm. The device configuration was ITO/In/aligned-PTCBI/TiOPc/PEDOT:PSS/Au and the thickness of each layer was optimized for polarization-sensitive photo-detection. The power-conversion efficiencies under the polarized white light parallel and perpendicular to the molecular-orientation axis, through the ITO electrode were 0.78% and 0.45%, respectively. The ratio of short-circuit current, parallel to perpendicular, was 1.66. This device can be used as transparent photo-detectors, because the transmittance of the Au electrode was about 40% at 500-600nm. The short-circuit current ratio was increased to 3.0, when 510nm monochromatic polarized light through the Au electrode was used.

  1. Thin film based semi-active resonant marker design for low profile interventional cardiovascular MRI devices.

    Science.gov (United States)

    Baysoy, Engin; Yildirim, Dursun Korel; Ozsoy, Cagla; Mutlu, Senol; Kocaturk, Ozgur

    2017-02-01

    A new microfabrication method to produce low profile radio frequency (RF) resonant markers on catheter shafts was developed. A semi-active RF resonant marker incorporating a solenoid and a plate capacitor was constructed on the distal shaft of a 5 Fr guiding catheter. The resulting device can be used for interventional cardiovascular MRI procedures. Unlike current semi-active device visualization techniques that require rigid and bulky analog circuit components (capacitor and solenoid), we fabricated a low profile RF resonant marker directly on guiding the catheter surface by thin film metal deposition and electroplating processes using a modified physical vapor deposition system. The increase of the overall device profile thickness caused by the semi-active RF resonant marker (130 µm thick) was lowered by a factor of 4.6 compared with using the thinnest commercial non-magnetic and rigid circuit components (600 µm thick). Moreover, adequate visibility performance of the RF resonant marker in different orientations and overall RF safety were confirmed through in vitro experiments under MRI successfully. The developed RF resonant marker on a clinical grade 5 Fr guiding catheter will enable several interventional congenital heart disease treatment procedures under MRI.

  2. Growth and Characterization of Polyimide-Supported AlN Films for Flexible Surface Acoustic Wave Devices

    Science.gov (United States)

    Li, Qi; Liu, Hongyan; Li, Gen; Zeng, Fei; Pan, Feng; Luo, Jingting; Qian, Lirong

    2016-06-01

    Highly c-axis oriented aluminum nitride (AlN) films, which can be used in flexible surface acoustic wave (SAW) devices, were successfully deposited on polyimide (PI) substrates by direct current reactive magnetron sputtering without heating. The sputtering power, film thickness, and deposition pressure were optimized. The characterization studies show that at the optimized conditions, the deposited AlN films are composed of columnar grains, which penetrate through the entire film thickness (~2 μm) and exhibit an excellent (0002) texture with a full width at half maximum value of the rocking curve equal to 2.96°. The film surface is smooth with a root mean square value of roughness of 3.79 nm. SAW prototype devices with a center frequency of about 520 MHz and a phase velocity of Rayleigh wave of about 4160 m/s were successfully fabricated using the AlN/PI composite structure. The obtained results demonstrate that the highly c-axis oriented AlN films with a smooth surface and low stress can be produced on relatively rough, flexible substrates, and this composite structure can be possibly used in flexible SAW devices.

  3. Processing and modeling issues for thin-film solar cell devices: Annual subcontract report, January 16, 1995 -- January 15, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Birkmire, R W; Phillips, J E; Buchanan, W A; Eser, E; Hegedus, S S; McCandless, B E; Meyers, P V; Shafarman, W N [Univ. of Delaware, Newark, DE (United States)

    1996-08-01

    The overall mission of the Institute of Energy Conversion is the development of thin film photovoltaic cells, modules, and related manufacturing technology and the education of students and professionals in photovoltaic technology. The objectives of this four-year NREL subcontract are to advance the state of the art and the acceptance of thin film PV modules in the areas of improved technology for thin film deposition, device fabrication, and material and device characterization and modeling, relating to solar cells based on CuInSe{sub 2} and its alloys, on a-Si and its alloys, and on CdTe. In the area of CuInSe{sub 2} and its alloys, EEC researchers have produced CuIn{sub 1-x}GaxSe{sub 2} films by selenization of elemental and alloyed films with H{sub 2}Se and Se vapor and by a wide variety of process variations employing co-evaporation of the elements. Careful design, execution and analysis of these experiments has led to an improved understanding of the reaction chemistry involved, including estimations of the reaction rate constants. Investigation of device fabrication has also included studies of the processing of the Mo, US and ZnO deposition parameters and their influence on device properties. An indication of the success of these procedures was the fabrication of a 15% efficiency CuIn{sub 1-x}GaxSe{sub 2} solar cell.

  4. Enhancement in figure-of-merit with superlattices structures for thin-film thermoelectric devices

    Energy Technology Data Exchange (ETDEWEB)

    Venkatasubramanian, R.; Colpitts, T.

    1997-07-01

    Thin-film superlattice (SL) structures in thermoelectric materials are shown to be a promising approach to obtaining an enhanced figure-of-merit, ZT, compared to conventional, state-of-the-art bulk alloyed materials. In this paper the authors describe experimental results on Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} and Si/Ge SL structures, relevant to thermoelectric cooling and power conversion, respectively. The short-period Bi{sub 2}Te{sub 3} and Si/Ge SL structures appear to indicate reduced thermal conductivities compared to alloys of these materials. From the observed behavior of thermal conductivity values in the Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} SL structures, a distinction is made where certain types of periodic structures may correspond to an ordered alloy rather than an SL, and therefore, do not offer a significant reduction in thermal conductivity values. The study also indicates that SL structures, with little or weak quantum-confinement, also offer an improvement in thermoelectric power factor over conventional alloys. They present power factor and electrical transport data in the plane of the SL interfaces to provide preliminary support for the arguments on reduced alloy scattering and impurity scattering in Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} and Si/Ge SL structures. These results, though tentative due to the possible role of the substrate and the developmental nature of the 3-{omega} method used to determine thermal conductivity values, suggest that the short-period SL structures potentially offer factorial improvements in the three-dimensional figure-of-merit (ZT3D) compared to current state-of-the-art bulk alloys. An approach to a thin-film thermoelectric device called a Bipolarity-Assembled, Series-Inter-Connected Thin-Film Thermoelectric Device (BASIC-TFTD) is introduced to take advantage of these thin-film SL structures.

  5. A novel fluorinated Eu(III) β-diketone complex as thin film for optical device applications

    Science.gov (United States)

    de Sá, Gilberto F.; Alves, Severino, Jr.; da Silva, Blenio J. P.; da Silva, Eronides F., Jr.

    1998-11-01

    We discuss the synthesis and spectroscopic characteristics of a thin film (˜30-90 nm) based on lanthanide europium (III) complexes as the emitter layers, to shift the UV portion of light spectrum into the visible region. The complex presents high quantum efficiency (˜65%), is highly volatile and thermodynamically stable. In addition, the thin film is used as an alternative antireflection coating on a silicon solar cell, allowing for an improvement of about 21% on cell efficiency. The high absorption and luminescence properties in the UV-visible region and its compatibility with device fabrication processes make this material of great potential for use in advanced optical device technologies.

  6. Harvesting Nanocatalytic Heat Localized in Nanoalloy Catalyst as a Heat Source in a Nanocomposite Thin Film Thermoelectric Device.

    Science.gov (United States)

    Zhao, Wei; Shan, Shiyao; Luo, Jin; Mott, Derrick M; Maenosono, Shinya; Zhong, Chuan-Jian

    2015-10-20

    This report describes findings of an investigation of harvesting nanocatalytic heat localized in a nanoalloy catalyst layer as a heat source in a nanocomposite thin film thermoelectric device for thermoelectric energy conversion. This device couples a heterostructured copper-zinc sulfide nanocomposite for thermoelectrics and low-temperature combustion of methanol fuels over a platinum-cobalt nanoalloy catalyst for producing heat localized in the nanocatalyst layer. The possibility of tuning nanocatalytic heat in the nanocatalyst and thin film thermoelectric properties by compositions points to a promising pathway in thermoelectric energy conversion.

  7. Characteristics of Al-doped ZnO films grown by atomic layer deposition for silicon nanowire photovoltaic device.

    Science.gov (United States)

    Oh, Byeong-Yun; Han, Jin-Woo; Seo, Dae-Shik; Kim, Kwang-Young; Baek, Seong-Ho; Jang, Hwan Soo; Kim, Jae Hyun

    2012-07-01

    We report the structural, electrical, and optical characteristics of Al-doped ZnO (ZnO:Al) films deposited on glass by atomic layer deposition (ALD) with various Al2O3 film contents for use as transparent electrodes. Unlike films fabricated by a sputtering method, the diffraction peak position of the films deposited by ALD progressively moved to a higher angle with increasing Al2O3 film content. This indicates that Zn sites were effectively replaced by Al, due to layer-by-layer growth mechanism of ALD process which is based on alternate self-limiting surface chemical reactions. By adjusting the Al2O3 film content, a ZnO:Al film with low electrical resistivity (9.84 x 10(-4) Omega cm) was obtained at an Al2O3 film content of 3.17%, where the Al concentration, carrier mobility, optical transmittance, and bandgap energy were 2.8 wt%, 11.20 cm2 V(-1) s(-1), 94.23%, and 3.6 eV, respectively. Moreover, the estimated figure of merit value of our best sample was 8.2 m7Omega(-1). These results suggest that ZnO:Al films deposited by ALD could be useful for electronic devices in which especially require 3-dimensional conformal deposition of the transparent electrode and surface passivation.

  8. Y1Ba2Cu3O(7-delta) thin film dc SQUIDs (superconducting quantum interference device)

    Science.gov (United States)

    Racah, Daniel

    1991-03-01

    Direct current superconducting quantum interferometers (SQUIDs) based on HTSC thin films have been measured and characterized. The thin films used were of different quality: (1) Granular films on Sapphire substrates, prepared either by e-gun evaporation, by laser ablation or by MOCVD (metal oxide chemical vapor deposition), (2) Epitaxial films on MgO substrates. Modulations of the voltage on the SQUIDs as a function of the applied flux have been observed in a wide range of temperatures. The nature of the modulation was found to be strongly dependent on the morphology of the film and on its critical current. The SQUIDs based on granular films were relatively noisy, hysteretic and with a complicated V-phi shape. Those devices based on low quality (lowIc) granular films could be measured only at low temperatures (much lower than 77 K). While those of higher quality (granular films with high Ic) could be measured near to the superconductive transition. The SQUID based on high quality epitaxial film was measured near Tc and showed an anomalous, time dependent behavior.

  9. Effect of Electric Field and Polarity on Light Emission in Metal-Insulator-Semiconductor Structure Thin-Film Electroluminescent Devices

    Science.gov (United States)

    Ohwaki, Jun-ichi; Kozawaguchi, Haruki; Tsujiyama, Bunjiro

    1983-01-01

    Changes in the emission intensities and spectra with applied electric fields in Metal-Insulator-Semiconductor (MIS) structure thin-film electroluminescent (TFEL) devices have been investigated using devices with stacked emitting layer structures, such as ITO/ZnS: Mn/ZnS: Tb/Sm2O3/Al. In MIS-TFEL devices, the emission distribution in the direction of the ZnS film thickness is nonhomogeneous. In particular, the emission intensity in the region near the ZnS-insulator interface increases with increasing applied voltage more than in the other region in the ZnS layer, when electrons exciting emission centers are accelerated from the insulator side. On the other hand, the emission is homogeneous at the opposite polarity. It is found that the emission color for stacked emitting layer MIS-TFEL devices can be modulated by changing the applied voltage.

  10. Creating an Information Literacy Badges Program in Blackboard: A Formative Program Evaluation

    Science.gov (United States)

    Tunon, Johanna; Ramirez, Laura Lucio; Ryckman, Brian; Campbell, Loy; Mlinar, Courtney

    2015-01-01

    A formative program evaluation using Stufflebeam's (2010) Context, Input, Process, Product (CIPP) model was conducted to assess the use of digital badges for tracking basic library instructional skills across academic programs at Nova Southeastern University. Based on the evaluation of pilot library modules and Blackboard Learn's badges…

  11. Creating an Information Literacy Badges Program in Blackboard: A Formative Program Evaluation

    Science.gov (United States)

    Tunon, Johanna; Ramirez, Laura Lucio; Ryckman, Brian; Campbell, Loy; Mlinar, Courtney

    2015-01-01

    A formative program evaluation using Stufflebeam's (2010) Context, Input, Process, Product (CIPP) model was conducted to assess the use of digital badges for tracking basic library instructional skills across academic programs at Nova Southeastern University. Based on the evaluation of pilot library modules and Blackboard Learn's badges…

  12. Learning Analytics and Digital Badges: Potential Impact on Student Retention in Higher Education

    Science.gov (United States)

    Mah, Dana-Kristin

    2016-01-01

    Learning analytics and digital badges are emerging research fields in educational science. They both show promise for enhancing student retention in higher education, where withdrawals prior to degree completion remain at about 30% in Organisation for Economic Cooperation and Development member countries. This integrative review provides an…

  13. Photographic film as a pocket radiation dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Pardue, L.A.; Goldstein, N.; Wollan, E.O.

    1944-04-25

    The energy dependence of film blackening is discussed and shown graphically. The exposure range of films is discussed, and blackening is plotted vs exposure for DuPont No. 502, and for the less sensitive DuPont No. 351. A plan is then described for monitoring radiation exposure to workers by requiring the worker to carry an x-ray film of dental packet size in a badge designed for the purpose. (LEW)

  14. Ultrafast All-Optical Phenomena and Devices Using Conjugated Polymer Thin Films

    Science.gov (United States)

    Hays, Andrew Wayne

    The Su-Schrieffer-Heeger formalism predicts shifts of oscillator strength from the valence and conduction bands to new sub-gap absorptions for both degenerate and nondegenerate ground state conjugated polymers. Photoinduced absorption studies on polyacetylene confirmed this behavior in degenerate ground state polymers. The shift in oscillator strength to form solitons takes place in less than one optical phonon period (family) with similar time scale for the creation of polarons and with time decays on the order of 10-1000 ps. These fast (and large) changes in the optical absorption spectrum suggest that the materials are excellent candidates for use in nonlinear optical devices and systems. Thin film waveguides are the obvious first choice. We have used the focused light attenuated total reflection technique (FLATR) to measure both the sign and the magnitude of the change in the complex index of refraction of a conjugated polymer in a waveguide configuration. In poly(3-hexylthiophene) we observe a picosecond decrease in the refractive index correlated with the subgap induced absorption. The magnitude of the picosecond modulation is | n_2 | ~eq 1 times 10^{ -4} (MW/cm^2)^{ -1}. Optical devices based on waveguiding are inherently serial devices. These sorts of devices would find use in general purpose digital optical computers and switching application for telecommunications. We have explored the possibility of using an engineered polymer in a parallel processing architecture. The final project in this thesis describes a femtosecond optical correlator based on degenerate four-wave mixing in the conjugated polymer poly (1,6 heptadiester) (PHDE). PHDE is a degenerate ground state polymer with a backbone similar to trans-polyacetylene. This material was synthesized to retain the ultrafast time response of polyacetylene and large optical nonlinearities. Additionally, side groups were added to yield solubility in organic solvents and improve environmental stability. Our

  15. Processing and modeling issues for thin-film solar cell devices. Annual subcontract report, January 16, 1994--January 15, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Birkmire, R.W.; Phillips, J.E.; Buchanan, W.A.; Hegedus, S.S.; McCandless, B.E.; Shafarman, W.N. [Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion

    1995-06-01

    This report describes results achieved during the second phase of a four year subcontract to develop and understand thin film solar cell technology related to a-Si and its alloys, CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2}, and CdTe. Accomplishments during this phase include, development of equations and reaction rates for the formation of CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} films by selenization, fabrication of a 15% efficient CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} cell, development of a reproducible, reliable Cu-diffused contact to CdTe, investigation of the role of CdTe-CdS interdiffusion on device operation, investigation of the substitution of HCl for CdCl{sub 2} in the post-deposition heat treatment of CdTe/CdS, demonstration of an improved reactor design for deposition of a-Si films, demonstration of improved process control in the fabrication of a ten set series of runs producing {approximately}8% efficient a-Si devices, demonstration of the utility of a simplified optical model for determining quantity and effect of current generation in each layer of a triple stacked a-Si cell, presentation of analytical and modeling procedures adapted to devices produced with each material system, presentation of baseline parameters for devices produced with each material system, and various investigations of the roles played by other layers in thin film devices including the Mo underlayer, CdS and ZnO in CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} devices, the CdS in CdTe devices, and the ZnO as window layer and as part of the back surface reflector in a-Si devices. In addition, collaborations with over ten research groups are briefly described. 73 refs., 54 figs., 34 tabs.

  16. Magneto-Seebeck effect in an ITO/PEDOT:PSS/Au thin-film device

    Directory of Open Access Journals (Sweden)

    Hongfeng Wang

    2016-04-01

    Full Text Available This article reports giant magnetic field effects on the Seebeck coefficient by exerting a Lorentz force on charge diffusion based on vertical multi-layer ITO/PEDOT:PSS/Au thin-film devices. The Lorentz force, induced by an external magnetic field, changes the charge transport and consequently generates angular dependent magnetoresistance. The proposed mechanism of the magneto-Seebeck effect is proved by measuring the magnetoresistance at a parallel, 45o and perpendicular angle to the temperature gradient. The gradual change of the magnetoresistance from a parallel to perpendicular angle indicates that the Lorentz force is a key driving force to develop the magneto-Seebeck effect. Therefore, our experimental results demonstrate a magnetic approach to control the thermoelectric properties in organic materials.

  17. Magneto-Seebeck effect in an ITO/PEDOT:PSS/Au thin-film device

    Science.gov (United States)

    Wang, Hongfeng; Liu, Qing; Tisdale, Jeremy; Xu, Ling; Liu, Yuchun; Hu, Bin

    2016-04-01

    This article reports giant magnetic field effects on the Seebeck coefficient by exerting a Lorentz force on charge diffusion based on vertical multi-layer ITO/PEDOT:PSS/Au thin-film devices. The Lorentz force, induced by an external magnetic field, changes the charge transport and consequently generates angular dependent magnetoresistance. The proposed mechanism of the magneto-Seebeck effect is proved by measuring the magnetoresistance at a parallel, 45o and perpendicular angle to the temperature gradient. The gradual change of the magnetoresistance from a parallel to perpendicular angle indicates that the Lorentz force is a key driving force to develop the magneto-Seebeck effect. Therefore, our experimental results demonstrate a magnetic approach to control the thermoelectric properties in organic materials.

  18. Transparent EuTiO3 films: a possible two-dimensional magneto-optical device

    Science.gov (United States)

    Bussmann-Holder, Annette; Roleder, Krystian; Stuhlhofer, Benjamin; Logvenov, Gennady; Lazar, Iwona; Soszyński, Andrzej; Koperski, Janusz; Simon, Arndt; Köhler, Jürgen

    2017-01-01

    The magneto-optical activity of high quality transparent thin films of insulating EuTiO3 (ETO) deposited on a thin SrTiO3 (STO) substrate, both being non-magnetic materials, are demonstrated to be a versatile tool for light modulation. The operating temperature is close to room temperature and allows for multiple device engineering. By using small magnetic fields birefringence of the samples can be switched off and on. Similarly, rotation of the sample in the field can modify its birefringence Δn. In addition, Δn can be increased by a factor of 4 in very modest fields with simultaneously enhancing the operating temperature by almost 100 K.

  19. Studies of ferroelectric heterostructure thin films, interfaces, and device-related processes via in situ analytical techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, S.; Auciello, O.; Dhote, A. M.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A.; Krauss, A. R.; Muller, A. H.; Ramesh, R.

    1999-06-29

    The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMS) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and device processes relevant to device development. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed. Direct imaging of ferroelectric domains under applied electric fields can provide valuable information to understand domain dynamics in ferroelectric films. We discuss results of piezoresponse scanning force microscopy (SFM) imaging for nanoscale studies of polarization reversal and retention loss in Pb(Zr{sub x}Ti{sub 1{minus}x})O{sub 3} (PZT)-based capacitors. Another powerful technique suitable for in situ, real-time characterization of film growth processes and ferroelectric film-based device operation is based on synchrotrons X-ray scattering, which is currently being implemented at Argonne National Laboratory.

  20. High-Performance Electrochromic Devices Based on Poly[Ni(salen)]-Type Polymer Films.

    Science.gov (United States)

    Nunes, Marta; Araújo, Mariana; Fonseca, Joana; Moura, Cosme; Hillman, Robert; Freire, Cristina

    2016-06-08

    We report the application of two poly[Ni(salen)]-type electroactive polymer films as new electrochromic materials. The two films, poly[Ni(3-Mesalen)] (poly[1]) and poly[Ni(3-MesaltMe)] (poly[2]), were successfully electrodeposited onto ITO/PET flexible substrates, and their voltammetric characterization revealed that poly[1] showed similar redox profiles in LiClO4/CH3CN and LiClO4/propylene carbonate (PC), while poly[2] showed solvent-dependent electrochemical responses. Both films showed multielectrochromic behavior, exhibiting yellow, green, and russet colors according to their oxidation state, and promising electrochromic properties with high electrochemical stability in LiClO4/PC supporting electrolyte. In particular, poly[1] exhibited a very good electrochemical stability, changing color between yellow and green (λ = 750 nm) during 9000 redox cycles, with a charge loss of 34.3%, an optical contrast of ΔT = 26.2%, and an optical density of ΔOD = 0.49, with a coloration efficiency of η = 75.55 cm(2) C(-1). On the other hand, poly[2] showed good optical contrast for the color change from green to russet (ΔT = 58.5%), although with moderate electrochemical stability. Finally, poly[1] was used to fabricate a solid-state electrochromic device using lateral configuration with two figures of merit: a simple shape (typology 1) and a butterfly shape (typology 2); typology 1 showed the best performance with optical contrast ΔT = 88.7% (at λ = 750 nm), coloration efficiency η = 130.4 cm(2) C(-1), and charge loss of 37.0% upon 3000 redox cycles.

  1. Agreement and reading time for differently-priced devices for the digital capture of X-ray films.

    Science.gov (United States)

    Salazar, Antonio José; Camacho, Juan Camilo; Aguirre, Diego Andrés

    2012-03-01

    We assessed the reliability of three digital capture devices: a film digitizer (which cost US $15,000), a flat-bed scanner (US $1800) and a digital camera (US $450). Reliability was measured as the agreement between six observers when reading images acquired from a single device and also in terms of the pair-device agreement. The images were 136 chest X-ray cases. The variables measured were the interstitial opacities distribution, interstitial patterns, nodule size and percentage pneumothorax size. The agreement between the six readers when reading images acquired from a single device was similar for the three devices. The pair-device agreements were moderate for all variables. There were significant differences in reading-time between devices: the mean reading-time for the film digitizer was 93 s, it was 59 s for the flat-bed scanner and 70 s for the digital camera. Despite the differences in their cost, there were no substantial differences in the performance of the three devices.

  2. Magneto-Optical Thin Films for On-Chip Monolithic Integration of Non-Reciprocal Photonic Devices

    Directory of Open Access Journals (Sweden)

    Mehmet Cengiz Onbasli

    2013-11-01

    Full Text Available Achieving monolithic integration of nonreciprocal photonic devices on semiconductor substrates has been long sought by the photonics research society. One way to achieve this goal is to deposit high quality magneto-optical oxide thin films on a semiconductor substrate. In this paper, we review our recent research activity on magneto-optical oxide thin films toward the goal of monolithic integration of nonreciprocal photonic devices on silicon. We demonstrate high Faraday rotation at telecommunication wavelengths in several novel magnetooptical oxide thin films including Co substituted CeO2−δ, Co- or Fe-substituted SrTiO3−δ, as well as polycrystalline garnets on silicon. Figures of merit of 3~4 deg/dB and 21 deg/dB are achieved in epitaxial Sr(Ti0.2Ga0.4Fe0.4O3−δ and polycrystalline (CeY2Fe5O12 films, respectively. We also demonstrate an optical isolator on silicon, based on a racetrack resonator using polycrystalline (CeY2Fe5O12/silicon strip-loaded waveguides. Our work demonstrates that physical vapor deposited magneto-optical oxide thin films on silicon can achieve high Faraday rotation, low optical loss and high magneto-optical figure of merit, therefore enabling novel high-performance non-reciprocal photonic devices monolithically integrated on semiconductor substrates.

  3. Development of a Handmade Conductivity Measurement Device for a Thin-Film Semiconductor and Its Application to Polypyrrole

    Science.gov (United States)

    Seng, Set; Shinpei, Tomita; Yoshihiko, Inada; Masakazu, Kita

    2014-01-01

    The precise measurement of conductivity of a semiconductor film such as polypyrrole (Ppy) should be carried out by the four-point probe method; however, this is difficult for classroom application. This article describes the development of a new, convenient, handmade conductivity device from inexpensive materials that can measure the conductivity…

  4. Holographic injection-locking of a broad-area laser diode via a photorefractive thin film device

    NARCIS (Netherlands)

    van Voorst, P.D.; de Wit, M.R.; Offerhaus, Herman L.; Tay, S.; Thomas, J.; Peyghambarian, N.; Boller, Klaus J.

    2007-01-01

    We demonstrate locking of a high power broad area laser diode to a single frequency using holographic feedback from a photorefractive polymer thin-film device for the first time. A four-wave mixing setup is used to generate feedback for the broad area diode at the wavelength of the single frequency

  5. Superlattice Multinanolayered Thin Films of SiO2/SiO2 + Ge for Thermoelectric Device Applications

    Science.gov (United States)

    2013-04-05

    REPORT Superlattice multinanolayered thin films of SiO2/SiO2 + Ge for thermoelectric device applications 14. ABSTRACT 16. SECURITY CLASSIFICATION OF...used as a physical vapor deposition ( PVD ) system since we have used only two electron guns to evaporate the crucibles without any gas assistance. The

  6. Development of a Handmade Conductivity Measurement Device for a Thin-Film Semiconductor and Its Application to Polypyrrole

    Science.gov (United States)

    Seng, Set; Shinpei, Tomita; Yoshihiko, Inada; Masakazu, Kita

    2014-01-01

    The precise measurement of conductivity of a semiconductor film such as polypyrrole (Ppy) should be carried out by the four-point probe method; however, this is difficult for classroom application. This article describes the development of a new, convenient, handmade conductivity device from inexpensive materials that can measure the conductivity…

  7. High temperature superconducting thin films and quantum interference devices (SQUIDs) for gradiometers

    CERN Document Server

    Graf zu Eulenburg, A

    1999-01-01

    the best balance and gradient sensitivity at 1kHz were 3x10 sup - sup 3 and 222fT/(cm sq root Hz))) respectively. The measured spatial response to a current carrying wire was in good agreement with a theoretical model. A significant performance improvement was obtained with the development of a single layer gradiometer with 13mm baseline, fabricated on 30x10mm sup 2 bicrystals. For such a device, the gradient sensitivity at 1kHz was 50fT/(cm sq root Hz)) and the gradiometer was used successfully for unshielded magnetocardiography. A parasitic effective area compensation scheme was employed with two neighbouring SQUIDs coupled in an opposite sense to the same gradiometer loop. This improved the balance from the intrinsic value of 10 sup - sup 3 to 3x10 sup - sup 5. This thesis describes several aspects of the development of gradiometers using high temperature Superconducting Quantum Interference Devices (SQUID). The pulsed laser deposition of thin films of YBa sub 2 Cu sub 3 O sub 7 sub - subdelta (YBCO) on Sr...

  8. Electronic and optoelectronic devices based on chirality-enriched wafer-scale single-wall carbon nanotube thin films

    Science.gov (United States)

    Gao, Weilu; He, Xiaowei; Xie, Lijuan; Zhang, Qi; Haroz, Erik; Doorn, Stephen K.; Kono, Junichiro

    2015-03-01

    The unique and rich material properties of single-wall carbon nanotubes (SWCNTs) make them attractive for nano-electronic and optoelectronic applications. Slight changes in tube diameter and wrapping angle, defined by the chirality indices (n, m), can dramatically modify the bandstructure, which can be utilized for designing devices with tailored properties. However, it remains to be a challenge to fabricate macroscopic, single-chirality devices. Here, we introduce a simple way of producing chirality-enriched wafer-scale SWCNT films by combining recently developed solution-based polymer-modified sorting method and vacuum filtration. The produced thin films can be easily transferred onto any substrate to have a CMOS compatible wafer. We fabricated a transistor of (6,5)-enriched SWCNTs with an on/off ratio >103. Large-scale photothermoelectric-effect-based and photovoltaic-effect-based photodetectors made of (6,6)- and (6,5)-enriched films, respectively, will also be discussed.

  9. Processing and modeling issues for thin-film solar cell devices. Annual subcontract report, January 16, 1993--January 15, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Birkmire, R.W.; Phillips, J.E.; Buchanan, W.A.; Hegedus, S.S.; McCandless, B.E.; Shafarman, W.N.; Yokimcus, T.A. [Institute of Energy Conversion, Newark, DE (United States)

    1994-09-01

    The overall objective of the research presented in this report is to advance the development and acceptance of thin-film photovoltaic modules by increasing the understanding of film growth and processing and its relationship to materials properties and solar cell performance. The specific means toward meeting this larger goal include: (1) investigating scalable, cost-effective deposition processes; (2) preparing thin-film materials and device layers and completed cell structures; (3) performing detailed material and device analysis; and (4) participating in collaborative research efforts that address the needs of PV-manufacturers. These objectives are being pursued with CuInSe{sub 2}, CdTe and a-Si based solar cells.

  10. Analysis and optimization of thin film photovoltaic materials and device fabrication by real time spectroscopic ellipsometry

    Science.gov (United States)

    Li, Jian; Stoke, Jason A.; Podraza, Nikolas J.; Sainju, Deepak; Parikh, Anuja; Cao, Xinmin; Khatri, Himal; Barreau, Nicolas; Marsillac, Sylvain; Deng, Xunming; Collins, Robert W.

    2007-09-01

    Methods of spectroscopic ellipsometry (SE) have been applied to investigate the growth and properties of the material components used in the three major thin film photovoltaics technologies: (1) hydrogenated silicon (Si:H); (2) cadmium telluride (CdTe); and (3) copper indium-gallium diselenide (CuIn 1-xGa xSe2 or CIGS). In Si:H technology, real time SE (RTSE) has been applied to establish deposition phase diagrams that describe very high frequency (vhf) plasmaenhanced chemical vapor deposition (PECVD) processes for hydrogenated silicon (Si:H) and silicon-germanium alloy (Si 1-xGe x:H) thin films. This study has reaffirmed that the highest efficiencies for a-Si:H and a-Si 1-xGe x:H component solar cells of multijunction devices are obtained when the i-layers are prepared under maximal H II dilution conditions. In CdTe technology, the magnetron sputter deposition of polycrystalline CdTe, CdS, and CdTe 1-xS x thin films as well as the formation of CdS/CdTe and CdTe/CdS heterojunctions has been studied. The nucleation and growth behaviors of CdTe and CdS show strong variations with deposition temperature, and this influences the ultimate grain size. The dielectric functions ɛ of the CdTe 1-xS x alloys have been deduced in order to set up a database for real time investigation of inter-diffusion at the CdS/CdTe and CdTe/CdS interfaces. In CIGS technology, strong variations in ɛ of the Mo back contact during sputter deposition have been observed, and these results have been understood applying a Drude relaxation time that varies with the Mo film thickness. Ex-situ SE measurements of a novel In IIS 3 window layer have shown critical point structures at 2.77+/-0.08 eV, 4.92+/-0.005 eV, and 5.64+/-0.005 eV, as well as an absorption tail with an onset near 1.9 eV. Simulations of solar cell performance comparing In IIS 3 and the conventional CdS have revealed similar quantum efficiencies, suggesting the possibility of a Cd-free window layer in CIGS technology.

  11. CMOS Compatible Nonvolatile Memory Devices Based on SiO2/Cu/SiO2 Multilayer Films

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; LIU Qi; LV Hang-Bing; LONG Shi-Bing; ZHANG Sen; LI Ying-Tao; LIAN Wen-Tai; YANG Jian-Hong; LIU Ming

    2011-01-01

    We systematically investigate the resistive switching characteristics of SiO2 films with a Cu/SiO2/Cu/SiO2/Pt multilayer structure. The device exhibits good resistive switching performances,including a high ON/OFF resistance ratio (>103),good retention characteristic (>104 s),satisfactory switching endurance (>200cycles),a fast programming speed (<100ns) and a high device yield (~100%).Considering these results,SiO2-based memories have highly promising applications for nonvolatile memory devices.

  12. Enhancement of Natural Convection by Carbon Nanotube Films Covered Microchannel-Surface for Passive Electronic Cooling Devices.

    Science.gov (United States)

    Zhang, Guang; Jiang, Shaohui; Yao, Wei; Liu, Changhong

    2016-11-16

    Owing to the outstanding properties of thermal conduction, lightweight, and chemical durability, carbon nanotubes (CNTs) have revealed promising applications in thermal management materials. Meanwhile, the increasingly popular portable electronics and the rapid development of space technology need lighter weight, smaller size, and more effective thermal management devices. Here, a novel kind of heat dissipation devices based on the superaligned CNT films and underlying microchannels is proposed, and the heat dissipation properties are measured at the natural condition. Distinctive from previous studies, by combining the advantages of microchannels and CNTs, such a novel heat dissipation device enables superior natural convection heat transfer properties. Our findings prove that the novel CNT-based devices could show an 86.6% larger total natural heat dissipation properties than bare copper plate. Further calculations of the radiation and natural convection heat transfer properties demonstrate that the excellent passive cooling properties of these CNT-based devices are primarily caused by the reinforcement of the natural convection heat transfer properties. Furthermore, the heat dissipation mechanisms are briefly discussed, and we propose that the very high heat transfer coefficients and the porous structures of superaligned CNT films play critical roles in reinforcing the natural convection. The novel CNT-based heat dissipation devices also have advantages of energy-saving, free-noise, and without additional accessories. So we believe that the CNT-based heat dissipation devices would replace the traditional metal-finned heat dissipation devices and have promising applications in electronic devices, such as photovoltaic devices, portable electronic devices, and electronic displays.

  13. Digital Badges for Professional Development: Supporting Library Personnel with the CLA School Library Standards

    Directory of Open Access Journals (Sweden)

    Sandra Bebbington

    2016-05-01

    Full Text Available The Canadian Library Association published Leading Learning, a library standards guide for school libraries in 2014. The Quebec School Librarians Network (QSLiN adapted these standards into a digital badge professional development program. Digital badges are a means for providing online learning, assessment and credentials in an interactive and dynamic way. They allow achievers to gain new knowledge and be recognized for skills and competencies that may otherwise go unnoticed. QSLiN’s digital badge program facilitates the transition of traditional school libraries into school Library Learning Commons. This badge program pilot project hopes to connect the Canadian school library community as well as provide an accessible and user-friendly form of professional development to all school library personnel regardless of their location. Research suggests that the two greatest barriers to professional development are time and money. As such, having a free online program helped to alleviate both barriers. This paper discusses the process we undertook at QSLiN to incorporate digital badges into our professional development initiatives. We will discuss the first phase of this pilot project as well as address future considerations for the program. L’Association canadienne des bibliothèques a publié Leading Learning, un guide sur les normes de bibliothèque, pour les bibliothèques scolaires en 2014. Le Québec School Librarians Network (QSLiN a adapté ces normes pour créer un programme de développement professionnel de badge numérique. Les badges numériques sont un moyen de fournir l’apprentissage, l’évaluation et la qualification en ligne de manière interactive et dynamique. Ils permettent aux personnes motivées d’acquérir des nouvelles connaissances et d’être reconnues pour des compétences qui pourraient sinon passer inaperçues. Le programme de badge numérique de QSLiN facilite la transition des bibliothèques scolaires

  14. Optical properties of Cd1-xZnxTe films in a device structure using variable angle spectroscopic ellipsometry

    Science.gov (United States)

    Paulson, P. D.; McCandless, B. E.; Birkmire, R. W.

    2004-03-01

    The optical properties of polycrystalline Cd1-xZnxTe alloy thin films in device structures are reported for energy from 0.8 to 4.6 eV. Cd1-xZnxTe alloy thin films with x from 0 to 1 were deposited on glass/indium-tin-oxide (ITO)/CdS substrates by coevaporation from CdTe and ZnTe sources and were characterized by variable angle spectroscopic ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffractometry. The Cd1-xZnxTe films are single phase with a zincblende crystal structure over the entire alloy range. The Cd1-xZnxTe optical constants were determined using a multilayer optical model incorporating the optical constants of glass, ITO and CdS, determined independently from glass, glass/ITO, and glass/ITO/CdS specimens. The optical constants of the Cd1-xZnxTe thin films are comparable to literature values reported for single crystals, indicating that the polycrystalline nature of the films does not measurably alter the optical constants. A semiconductor alloy model for determining the composition of CdxZn1-xTe alloy films is developed using the optical data obtained from the analysis. This alloy model can be used to evaluate compositional grading and the effects of Cd1-xZnxTe film processing.

  15. The possible effect on personnel dose by two copper filters covering Element 1 of the Harshaw 8814 TLD badge.

    Science.gov (United States)

    Reciniello, R N; Sengupta, S; Thompson, R L

    2009-08-01

    Ongoing uncertainties have existed regarding possible effects at low photon energies of two copper filters covering Element 1 of the Harshaw Type-8814 thermoluminescent dosimeter badge casing. To address these, Brookhaven National Laboratory's (BNL) Personnel Monitoring Group conducted a test in which Type-8814 badges with one copper filter covering Element 1 were irradiated at several low-energy levels side-by-side with the same number of badges with two copper filters covering Element 1. A review of exposures to personnel at Brookhaven Laboratory to possible low-energy photon flux was also conducted. From both the test and the review of exposures, it can be concluded that, for radiological work under the conditions at BNL, there is no apparent dosimetric difference if one or two copper filters cover Element 1 of the Type-8814 badge.

  16. Fabrication of fullerene nano-strucutres in mixed films and devices utilizing fullerene nano-structures

    KAUST Repository

    Zhong, Yufei

    2017-04-06

    Embodiments provide methods for controlling crystallization of fullerene compounds in mixed films comprising one or more polymers. Methods can include depositing fullerene mixed films comprising one or more polymers on crystalline fullerene substrates and annealing the deposited mixed films. Methods can further include one or more of exposing the annealed mixed film to UV light, and washing the annealed mixed film with a solvent. Fullerene compounds can include one or more of PCBM, PCBNB, and PCBA.

  17. Unified Numerical Solver for Device Metastabilities in CdTe Thin-Film PV

    Energy Technology Data Exchange (ETDEWEB)

    Vasileska, Dragica [Arizona State Univ., Tempe, AZ (United States)

    2017-08-17

    Thin-film modules of all technologies often suffer from performance degradation over time. Some of the performance changes are reversible and some are not, which makes deployment, testing, and energy-yield prediction more challenging. Manufacturers de-vote significant empirical efforts to study these phenomena and to improve semiconduc-tor device stability. Still, understanding the underlying reasons of these instabilities re-mains clouded due to the lack of ability to characterize materials at atomistic levels and the lack of interpretation from the most fundamental material science. The most com-monly alleged causes of metastability in CdTe device, such as “migration of Cu,” have been investigated rigorously over the past fifteen years. Still, the discussion often ended prematurely with stating observed correlations between stress conditions and changes in atomic profiles of impurities or CV doping concentration. Multiple hypotheses sug-gesting degradation of CdTe solar cell devices due to interaction and evolution of point defects and complexes were proposed, and none of them received strong theoretical or experimental confirmation. It should be noted that atomic impurity profiles in CdTe pro-vide very little intelligence on active doping concentrations. The same elements could form different energy states, which could be either donors or acceptors, depending on their position in crystalline lattice. Defects interact with other extrinsic and intrinsic de-fects; for example, changing the state of an impurity from an interstitial donor to a sub-stitutional acceptor often is accompanied by generation of a compensating intrinsic in-terstitial donor defect. Moreover, all defects, intrinsic and extrinsic, interact with the elec-trical potential and free carriers so that charged defects may drift in the electric field and the local electrical potential affects the formation energy of the point defects. Such complexity of interactions in CdTe makes understanding of

  18. Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices.

    Science.gov (United States)

    Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

    2016-06-03

    Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W(-1), external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

  19. Non-Epitaxial Thin-Film Indium Phosphide Photovoltaics: Growth, Devices, and Cost Analysis

    Science.gov (United States)

    Zheng, Maxwell S.

    In recent years, the photovoltaic market has grown significantly as module prices have continued to come down. Continued growth of the field requires higher efficiency modules at lower manufacturing costs. In particular, higher efficiencies reduce the area needed for a given power output, thus reducing the downstream balance of systems costs that scale with area such as mounting frames, installation, and soft costs. Cells and modules made from III-V materials have the highest demonstrated efficiencies to date but are not yet at the cost level of other thin film technologies, which has limited their large-scale deployment. There is a need for new materials growth, processing and fabrication techniques to address this major shortcoming of III-V semiconductors. Chapters 2 and 3 explore growth of InP on non-epitaxial Mo substrates by MOCVD and CSS, respectively. The results from these studies demonstrate that InP optoelectronic quality is maintained even by growth on non-epitaxial metal substrates. Structural characterization by SEM and XRD show stoichiometric InP can be grown in complete thin films on Mo. Photoluminescence measurements show peak energies and widths to be similar to those of reference wafers of similar doping concentrations. In chapter 4 the TF-VLS growth technique is introduced and cells fabricated from InP produced by this technique are characterized. The TF-VLS method results in lateral grain sizes of >500 mum and exhibits superior optoelectronic quality. First generation devices using a n-TiO2 window layer along with p-type TF-VLS grown InP have reached ˜12.1% power conversion efficiency under 1 sun illumination with VOC of 692 mV, JSC of 26.9 mA/cm2, and FF of 65%. The cells are fabricated using all non-epitaxial processing. Optical measurements show the InP in these cells have the potential to support a higher VOC of ˜795 mV, which can be achieved by improved device design. Chapter 5 describes a cost analysis of a manufacturing process using an

  20. Carbon Nanotube-Poly(vinylalcohol) Nanocomposite Film Devices: Applications for Femtosecond Fiber Laser Mode Lockers and Optical Amplifier Noise Suppressors

    Science.gov (United States)

    Sakakibara, Youichi; Rozhin, Aleksey G.; Kataura, Hiromichi; Achiba, Yohji; Tokumoto, Madoka

    2005-04-01

    We fabricated single-wall carbon nanotube (SWNT)/poly(vinylalcohol) (PVA) nanocomposite freestanding films and examined their application in devices in which the saturable absorption of SWNTs at near-infrared optical telecommunication wavelengths can be utilized. In a passively mode-locked fiber laser, we integrated a 30-μm-thick SWNT/PVA film into a fiber connection adaptor with the film sandwiched by a pair of fiber ferrules. A ring fiber laser with a SWNT/PVA saturable absorber was operated very easily in the mode-locked short-pulse mode with a pulse width of about 500 fs. Reproducible stable device performance was confirmed. In examining noise suppression for optical amplifiers, mixed light of semiconductor amplified spontaneous emission (ASE) source and 370 fs laser pulses was passed through a 100-μm-thick SWNT/PVA film. The transmission loss of the femtosecond pulse light was smaller than that of the ASE light. This proved that the SWNT/PVA film has the ability to suppress ASE noise.

  1. CdTe:Ge/Si (100) thin films grown by pulsed laser deposition (PLD) for photonic devices

    Science.gov (United States)

    Neretina, S.; Hughes, R. A.; Preston, J. S.; Sochinskii, N. V.; Mascher, P.

    2005-09-01

    Cadmium Telluride (CdTe) is a well known photonic material in the fields of infrared imaging and solar cells. Its nonlinear optical properties also make it a promising candidate for novel telecom applications that would utilize its high Kerr coefficient to produce advanced logical devices such as switches, routers and wavelength converters. The large photorefractive effect observed in CdTe also makes possible high-speed devices suitable for optical data processing. In order to advance such photorefractive waveguide applications, we have deposited CdTe films on silicon substrates with a native oxide layer using the pulsed laser deposition technique (PLD). Silicon was chosen as the substrate material as it is suitable for the monolithic integration of logical devices. Maintaining an oxide layer was deemed necessary as a high refractive index mismatch is desirable for high-index contrast waveguide based applications and such an index mismatch could be provided by a reasonably thick layer of SiO2. Films exhibiting some structural deficiencies, but with high optical quality were deposited through the optimization of the growth parameters. X-ray diffraction data indicates that the films are [111] oriented with rocking curves of substantial width. Atomic force microscopy images confirm that the films have a smooth surface morphology as was suggested by their mirror-like appearance. Using the optimum growth conditions, CdTe films doped with germanium were also deposited as this dopant introduces deep donor levels that enhance the photorefractive effect. A comparison of the optical properties obtained from the doped and undoped films indicate that impurities can have a marked effect on the index of refraction and extinction coefficient. Such alterations to the optical constants must be considered in the design of waveguide structures.

  2. Investigation of optical band gap and device parameters of rubrene thin film prepared using spin coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Tuğluoğlu, Nihat, E-mail: tugluo@gmail.com [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Barış, Behzad; Gürel, Hatice [Department of Physics, Faculty of Arts and Sciences, Giresun University, Gazipaşa Campus, Giresun 28100 (Turkey); Karadeniz, Serdar [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Yüksel, Ömer Faruk [Department of Physics, Faculty of Science, Selçuk University, Campus Konya 42075 (Turkey)

    2014-01-05

    Highlights: • Thin film of rubrene has been deposited by spin coating technique. • The band gap properties of the film were investigated in the range 200–700 nm. • The analysis of the absorption coefficient revealed indirect allowed transition. • The parameters such as barrier height and ideality factor were determined. -- Abstract: Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200–700 nm. The results of the absorption coefficient (α) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV–vis region shows two peaks at 250 nm and 300 nm. The analysis of the spectral behavior of the absorption coefficient (α) in the absorption region revealed indirect allowed transition with corresponding energy 2.31 eV. The value of Urbach energy (E{sub U}) was determined to be 1.169 eV. The current–voltage (I–V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I–V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions.

  3. General Top-Down Ion Exchange Process for the Growth of Epitaxial Chalcogenide Thin Films and Devices

    KAUST Repository

    Xia, Chuan

    2016-12-30

    We demonstrate a versatile top-down ion exchange process, done at ambient temperature, to form epitaxial chalcogenide films and devices, with nanometer scale thickness control. To demonstrate the versatility of our process we have synthesized (1) epitaxial chalcogenide metallic and semiconducting films and (2) free-standing chalcogenide films and (3) completed in situ formation of atomically sharp heterojunctions by selective ion exchange. Epitaxial NiCo2S4 thin films prepared by our process show 115 times higher mobility than NiCo2S4 pellets (23 vs 0.2 cm(2) V-1 s(-1)) prepared by previous reports. By controlling the ion exchange process time, we made free-standing epitaxial films of NiCo2S4 and transferred them onto different substrates. We also demonstrate in situ formation of atomically sharp, lateral Schottky diodes based on NiCo2O4/NiCo2S4 heterojunction, using a single ion exchange step. Additionally, we show that our approach can be easily extended to other chalcogenide semiconductors. Specifically, we used our process to prepare Cu1.8S thin films with mobility that matches single crystal Cu1.8S (25 cm(2) V-1 s(-1)), which is ca. 28 times higher than the previously reported Cu1.8S thin film mobility (0.58 cm(2) V-1 s(-1)), thus demonstrating the universal nature of our process. This is the first report in which chalcogenide thin films retain the epitaxial nature of the precursor oxide films, an approach that will be useful in many applications.

  4. Effect of the preparation procedure on the morphology of thin TiO₂ films and their device performance in small-molecule bilayer hybrid solar cells.

    Science.gov (United States)

    Unger, Eva L; Spadavecchia, Francesca; Nonomura, Kazuteru; Palmgren, Pål; Cappelletti, Giuseppe; Hagfeldt, Anders; Johansson, Erik M J; Boschloo, Gerrit

    2012-11-01

    Flat titanium dioxide films, to be used as the acceptor layer in bilayer hybrid solar cell devices, were prepared by spray-pyrolysis and by spin-casting. Both preparation methods resulted in anatase titania films with similar optical and electronic properties but considerably different film morphologies. Spray pyrolysis resulted in dense TiO₂ films grown onto and affected by the surface roughness of the underlying conducting glass substrates. The spin-casting preparation procedure resulted in nanoporous titania films. Hybrid solar cell devices with varying layer thickness of the small-molecule semiconducting dye TDCV-TPA were investigated. Devices built with spray-pyrolyzed titania substrates yielded conversion efficiencies up to 0.47%. Spin-cast titania substrates exhibited short circuits for thin dye layer thickness. For thicker dye layers the performance of these devices was up to 0.6% due to the higher interfacial area for charge separation of these nanoporous TiO₂ substrates.

  5. A new type of HTc superconducting film comb-shape resonator for radio frequency superconducting quantum interference devices

    Institute of Scientific and Technical Information of China (English)

    MAO Hai-yan; WANG Fu-ren; MENG Shu-chao; MAO Bo; LI Zhuang-zhi; NIE Rui-juan; LIU Xin-yuan; DAI Yuan-dong

    2006-01-01

    A new type of HTc superconducting film combshape resonator for radio frequency superconducting quantum interference devices (RF SQUID) has been designed.This new type of superconducting film comb-shape resonator is formed by a foursquare microstrip line without a flux concentrator.The range of the center frequency of this type of resonator varies from 800 MHz to 1300 MHz by changing the length of the teeth.In this paper,we report on simulating the relationship of the value of the center frequency and the length of the teeth,and testing the noise of HTc RF SQUID coupling this comb-shape resonator.

  6. Thermo-optical properties of 1H[3,4-b] quinoline films used in electroluminescent devices

    Science.gov (United States)

    Jaglarz, Janusz; Kępińska, Mirosława; Sanetra, Jerzy

    2014-06-01

    Electroluminescence cells with H[3,4-b] quinoline layers are promising devices for a blue light emitting EL diode. This work measured the optical reflectance as a function of temperature in copolymers PAQ layers deposited on Si crystalline substrate. Using the extended Cauchy dispersion model of the film refractive index we determined the thermo-optical coefficients for quinoline layers in the temperature range of 76-333 K from combined ellipsometric and spectrofotometric studies. The obtained values of thermo-optical coefficients of thin PAQ film, were negative and ranged in 5-10 × 10-4 [1/K].

  7. Recognising Informal Elearning with Digital Badging: Evidence for a Sustainable Business Model

    Directory of Open Access Journals (Sweden)

    Patrina Law

    2015-11-01

    Full Text Available Digital badging as a trend in education is now recognised. It offers a way to reward and motivate, providing evidence of skills and achievements. Badged Open Courses (BOCs were piloted by The Open University (OU in 2013. The project built on research into the motivations and profiles of learners using free educational resources which the OU makes available through its OpenLearn platform (Law, Perryman & Law, 2013. This research found that an increasing proportion of learners are keen to have their informal learning achievements recognised (Law & Law, 2014. Based on these data, a suite of free BOCs, assessed through the deployment of Moodle quizzes, was launched. This paper reports on evaluation of the BOCs and what we now know of the strategic importance of informal learning recognition. The initiative aligns with University strategies to provide accessible routes into formal learning for those who might not otherwise have the opportunity.

  8. Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V

    Science.gov (United States)

    Basiricò, Laura; Ciavatti, Andrea; Cramer, Tobias; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2016-10-01

    The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 104 and 77,000 nC mGy-1 cm-3, respectively.

  9. Fabrication of SnO2 based CO gas sensor device using thick film technology

    Science.gov (United States)

    Hermida, I. D. P.; Wiranto, G.; Hiskia; Nopriyanti, R.

    2016-11-01

    This research was aimed at fabricating a CO gas sensor based on SnO2 material synthesized using sol-gel method. The sensor components include thin film gold electrode and a PdAg heater screen printed on the backside of the alumina substrate. The device was tested to study the effect of temperature variation on the resistivity of the heater component, and the response of the SnO2 sensitive layer to 10 ppm CO gas. The SnO2 layer was characterized using SEM and EDS to determine the morphology and composition of the material. It was found that the SnO2 sensitive layer contained 21.21% C atoms, 22.43% O atoms, 14.98% Si atoms, 0.34% Cr atoms, 1.16% Ag atoms, 1.78% Sn atoms, and 38.11% Au atoms. The sensor sensitivity to CO gas increased with increasing temperature. The Operational temperature of this sensor was 95° C with the highest sensitivity value obtained was 16.59.

  10. Maternal effects, malaria infections and the badge size of the house sparrow

    Institute of Scientific and Technical Information of China (English)

    Philip L.G.Birget; Stephen D.Larcombe

    2015-01-01

    Background: The evolution of sexual signals is not only determined by immediate sexual selection but also by selection arising from the environment and the interaction with developmental effects.In this study we aimed to investigate how the badge size of male house sparrows(Passer domesticus) is correlated to avian malaria infections as well as to prenatal testosterone exposure,measured as the 2D:4D digit ratio.The rationale behind this study is that the immunosuppressive effect of maternal testosterone deposition combined with the fitness cost imposed by parasites may cause important trade-offs to the development of secondary sexual signals.Methods: Assuming that vector abundance is a key variable associated with infection risk by avian malaria,we caught adult male sparrows from eight different populations in the Camargue,France,four of which were located in a vector-controlled area,and the other four in an untreated area.For each bird we measured its badge size,digit ratio and took blood to determine its infections status.We used PCR to identify the malaria parasite species and strain that caused the infection.Results: Contrary to our expectation,prevalence of disease did not differ across the vector-treatment regions,with around 80 % of birds being infected in both areas,and those infections were caused largely by a single strain,Plasmodium relictum SGS1.Although infected birds had a badge size not significantly different from uninfected males,there was a condition-dependent association between badge size,infection status and maternal testosterone deposition.Conclusions: This study illustrates that the complexity of temporal and ecological dimensions makes the relationships between disease,testosterone-related traits and secondary sexual signals that have been previously reported less general than thought.

  11. Epitaxial Ni{sub 3}FeN thin films: A candidate for spintronic devices and magnetic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Loloee, Reza [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)

    2012-07-15

    A new type of epitaxial ferromagnetic nitride (Ni{sub 3} Fe N = permalloy nitride = 'PyN') compound films were grown on Al{sub 2}O{sub 3}(1120) substrates using reactive triode magnetron sputtering. The results of electron back-scattering diffraction and x-ray diffraction techniques indicate a high quality epitaxial crystalline structure with growth normal of (100). Magnetization measurements of epitaxial PyN films revealed several unique results. (1) A textbook square hysteresis loop that suggest existence of single magnetic domain in these films. (2) A coercive field is tunable from a few mOe up to a few Oe by changing the film thickness. (3) A magnetization that switches (rotate) over a very small field range of {delta}H{sub C} {<=} 0.05 Oe, independent of the film thickness. This small {delta}H indicates a very large resistive sensitivity ({delta}R/{delta}H) of the epitaxial PyN. (4) The epitaxial PyN thermal cycling through several cycles between '2 and 800 K' (-271 Degree-Sign C to +527 Degree-Sign C) shows much less degradation only about 2-5% compared to 40% degradation of a simple Py film. Four-probe transport measurements give an anisotropic magnetoresistance of Almost-Equal-To 6%, sufficiently higher than other known ferromagnetic materials. These interesting properties are ideal for a variety of spintronic devices and magnetic sensors.

  12. Deposition of magnesium nitride thin films on stainless steel-304 substrates by using a plasma focus device

    Science.gov (United States)

    Ramezani, Amir Hoshang; Habibi, Maryam; Ghoranneviss, Mahmood

    2014-08-01

    In this research, for the first time, we synthesize magnesium nitride thin films on 304-type stainless steel substrates using a Mather-type (2 kJ) plasma focus (PF) device. The films of magnesium nitride are coated with different number of focus shots (like 15, 25 and 35) at a distance of 8 cm from the anode tip and at 0° angular position with respect to the anode axis. For investigation of the structural properties and surface morphology of magnesium nitride films, we utilized the X-ray diffractometer (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis, respectively. Also, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. Furthermore, Vicker's microhardness is used to study the mechanical properties of the deposited films. The results show that the degree of crystallinity of deposited thin films (from XRD), the average size of particles and surface roughness (from AFM), crystalline growth of structures (from SEM) and the hardness values of the films depend on the number of focus shots. The EDX analysis demonstrates the existence of the elemental composition of magnesium in the deposited samples.

  13. Method for Aluminum Oxide Thin Films Prepared through Low Temperature Atomic Layer Deposition for Encapsulating Organic Electroluminescent Devices

    Directory of Open Access Journals (Sweden)

    Hui-Ying Li

    2015-02-01

    Full Text Available Preparation of dense alumina (Al2O3 thin film through atomic layer deposition (ALD provides a pathway to achieve the encapsulation of organic light emitting devices (OLED. Unlike traditional ALD which is usually executed at higher reaction n temperatures that may affect the performance of OLED, this application discusses the development on preparation of ALD thin film at a low temperature. One concern of ALD is the suppressing effect of ambient temperature on uniformity of thin film. To mitigate this issue, the pumping time in each reaction cycle was increased during the preparation process, which removed reaction byproducts and inhibited the formation of vacancies. As a result, the obtained thin film had both high uniformity and density properties, which provided an excellent encapsulation performance. The results from microstructure morphology analysis, water vapor transmission rate, and lifetime test showed that the difference in uniformity between thin films prepared at low temperatures, with increased pumping time, and high temperatures was small and there was no obvious influence of increased pumping time on light emitting performance. Meanwhile, the permeability for water vapor of the thin film prepared at a low temperature was found to reach as low as 1.5 × 10−4 g/(m2·day under ambient conditions of 25 °C and 60% relative humidity, indicating a potential extension in the lifetime for the OLED.

  14. Transport physics and device modeling of zinc oxide thin-film transistors. Pt. II: Contact Resistance in Short Channel Devices

    NARCIS (Netherlands)

    Torricelli, F.; Meijboom, J.R.; Smits, E.; Tripathi, A.K.; Gelinck, G.H.; Colalongo, L.; Kovacs-Vajna, Z.M.; Leeuw, D. de; Cantatore, E.

    2011-01-01

    Abstract—Short-channel zinc oxide (ZnO) thin-film transistors (TFTs) are investigated in a wide range of temperatures and bias conditions. Scaling down the channel length, the TFT performance is seriously affected by contact resistances, which depend on gate voltage and temperature. To account for t

  15. Transport physics and device modeling of zinc oxide thin-film transistors. Pt. I: Long-channel devices

    NARCIS (Netherlands)

    Torricelli, F.; Meijboom, J.R.; Smits, E.; Tripathi, A.K.; Ferroni, M.; Federici, S.; Gelinck, G.H.; Colalongo, L.; Kovacs-Vajna, Z.M.; Leeuw, D. de; Cantatore, E.

    2011-01-01

    Thin-film transistors (TFTs), which use zinc oxide (ZnO) as an active layer, were fabricated and investigated in detail. The transport properties of ZnO deposited by spray pyrolysis (SP) on a TFT structure are studied in a wide range of temperatures, electrical conditions (i.e., subthreshold, above-

  16. Self-learning ability realized with a resistive switching device based on a Ni-rich nickel oxide thin film

    Science.gov (United States)

    Liu, Y.; Chen, T. P.; Liu, Z.; Yu, Y. F.; Yu, Q.; Li, P.; Fung, S.

    2011-12-01

    The resistive switching device based on a Ni-rich nickel oxide thin film exhibits an inherent learning ability of a neural network. The device has the short-term-memory and long-term-memory functions analogous to those of the human brain, depending on the history of its experience of voltage pulsing or sweeping. Neuroplasticity could be realized with the device, as the device can be switched from a high-resistance state to a low-resistance state due to the formation of stable filaments by a series of electrical pulses, resembling the changes such as the growth of new connections and the creation of new neurons in the brain in response to experience.

  17. Thin-film growth and patterning techniques for small molecular organic compounds used in optoelectronic device applications.

    Science.gov (United States)

    Biswas, Shaurjo; Shalev, Olga; Shtein, Max

    2013-01-01

    Rapid advances in research and development in organic electronics have resulted in many exciting discoveries and applications, including organic light-emitting devices for information display and illumination, solar cells, photodetectors, chemosensors, and logic. Organic optoelectronic materials are broadly classified as polymeric or small molecular. For the latter category, solvent-free deposition techniques are generally preferred to form well-defined interfaces and improve device performance. This article reviews several deposition and patterning methods for small molecular thin films and devices, including organic molecular beam deposition, vacuum thermal evaporation, organic vapor phase deposition, and organic vapor jet printing, and compares them to several other methods that have been proposed recently. We hope this review provides a compact but informative summary of the state of the art in organic device processing and addresses the various techniques' governing physical principles.

  18. Oxygen-Induced Degradation in C60-Based Organic Solar Cells: Relation Between Film Properties and Device Performance.

    Science.gov (United States)

    Bastos, João P; Voroshazi, Eszter; Fron, Eduard; Brammertz, Guy; Vangerven, Tim; Van der Auweraer, Mark; Poortmans, Jef; Cheyns, David

    2016-04-20

    Fullerene-based molecules are the archetypical electron-accepting materials for organic photovoltaic devices. A detailed knowledge of the degradation mechanisms that occur in C60 layers will aid in the development of more stable organic solar cells. Here, the impact of storage in air on the optical and electrical properties of C60 is studied in thin films and in devices. Atmospheric exposure induces oxygen-trap states that are 0.19 eV below the LUMO of the fullerene C60. Moreover, oxygen causes a 4-fold decrease of the exciton lifetime in C60 layers, resulting in a 40% drop of short-circuit current from optimized planar heterojunction solar cells. The presence of oxygen-trap states increases the saturation current of the device, resulting in a 20% loss of open-circuit voltage. Design guidelines are outlined to improve air stability for fullerene-containing devices.

  19. Application of radiation physics in the design of the Harshaw 8828 beta-gamma TLD badge

    Energy Technology Data Exchange (ETDEWEB)

    Chase, W.J. [Health Physics Department, Ontario Power Generation, Whitby, Ont., L1N 9E3 (Canada)], E-mail: john.chase@opg.com; Hirning, C.R. [Toronto, Ont. (Canada)

    2008-02-15

    A thermoluminescent dosimeter (TLD) badge has been developed to measure beta and gamma doses for routine personal dosimetry. The badge uses a card with four elements of LiF:Mg,Ti enriched in {sup 7}Li and sandwiched between layers of Teflon{sup TM}. The Element 1 filter is 1000mgcm{sup -2} of low-Z material, the Element 2 filter is 464mgcm{sup -2} of tin plus 536mgcm{sup -2} of low-Z material, the Element 3 filter is a 5-7mgcm{sup -2} Mylar window, and the Element 4 filter is 64mgcm{sup -2} of low-Z material. The filters for Elements 2 and 4 were optimized by testing and by application of radiation physics principles and calculation. Elements 1 and 2 are used to measure the response to photons, and from these results, H{sub p}(10), H{sub p}(0.07) for photons, and the photon contribution to the signals for Elements 3 and 4 are obtained. The photon contribution to the signals from Elements 3 and 4 is subtracted from their total signals to obtain two signals due to betas. These are used to derive a corrected value for H{sub p}(0.07) for betas. The badge has been in use since early 1999, and provides accurate results in a nuclear power station environment.

  20. Building-Integrated Solar Energy Devices based on Wavelength Selective Films

    Science.gov (United States)

    Ulavi, Tejas

    A potentially attractive option for building integrated solar is to employ hybrid solar collectors which serve dual purposes, combining solar thermal technology with either thin film photovoltaics or daylighting. In this study, two hybrid concepts, a hybrid photovoltaic/thermal (PV/T) collector and a hybrid 'solar window', are presented and analyzed to evaluate technical performance. In both concepts, a wavelength selective film is coupled with a compound parabolic concentrator (CPC) to reflect and concentrate the infrared portion of the solar spectrum onto a tubular absorber. The visible portion of the spectrum is transmitted through the concentrator to either a thin film Cadmium Telluride (CdTe) solar panel for electricity generation or into the interior space for daylighting. Special attention is given to the design of the hybrid devices for aesthetic building integration. An adaptive concentrator design based on asymmetrical truncation of CPCs is presented for the hybrid solar window concept. The energetic and spectral split between the solar thermal module and the PV or daylighting module are functions of the optical properties of the wavelength selective film and the concentrator geometry, and are determined using a Monte Carlo Ray-Tracing (MCRT) model. Results obtained from the MCRT can be used in conjugation with meteorological data for specific applications to study the impact of CPC design parameters including the half-acceptance angle thetac, absorber diameter D and truncation on the annual thermal and PV/daylighting efficiencies. The hybrid PV/T system is analyzed for a rooftop application in Phoenix, AZ. Compared to a system of the same area with independent solar thermal and PV modules, the hybrid PV/T provides 20% more energy, annually. However, the increase in total delivered energy is due solely to the addition of the thermal module and is achieved at an expense of a decrease in the annual electrical efficiency from 8.8% to 5.8% due to shading by

  1. Optimization of processing and modeling issues for thin film solar cell devices: Final report, February 3, 1997--September 1, 1998

    Energy Technology Data Exchange (ETDEWEB)

    Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Hegedus, S. S.; McCandless, B. E.

    2000-02-28

    This final report describes results achieved under a 20-month NREL subcontract to develop and understand thin-film solar cell technology associated to CuInSe{sub 2} and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE's long-range efficiency, reliability and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for the development of viable commercial processes and to improve module performance. The generic research issues addressed are: (1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; (2) device characterization relating the device performance to materials properties and process conditions; (3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; (4) development and improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to device structure and module encapsulation.

  2. Reduction of RESET current in phase change memory devices by carbon doping in GeSbTe films

    Science.gov (United States)

    Park, J. H.; Kim, S.-W.; Kim, J. H.; Wu, Z.; Cho, S. L.; Ahn, D.; Ahn, D. H.; Lee, J. M.; Nam, S. U.; Ko, D.-H.

    2015-03-01

    Phase Change Memory (PCM) has been proposed for use as a substitute for flash memory to satisfy the huge demands for high performance and reliability that promise to come in the next generation. In spite of its high scalability, reliability, and simple structure, high writing current, e.g., RESET current, has been a significant obstacle to achieving a high density in storage applications and the low power consumption required for use in mobile applications. We report herein on an attempt to determine the level of carbon incorporated into a GeSbTe (GST) film that is needed to reduce the RESET current of PCM devices. The crystal structure of the film was transformed into an amorphous phase by carbon doping, the stability of which was enhanced with increasing carbon content. This was verified by the small grain size and large band gap that are typically associated with carbon. The increased level of C-Ge covalent bonding is responsible for these enhancements. Thus, the resistance of the carbon doped Ge2Sb2Te5 film was higher than that for an undoped GST film by a factor of 2 orders of magnitude after producing a stable face-centered cubic phase by annealing. As a consequence, the PCM devices showed a significant reduction in RESET current as low as 23% when the carbon content was increased to 11.8 at. %. This can be attributed to the elevated SET resistance, which is proportional to the dynamic resistance of the PCM device, caused by the high resistance due to a carbon doped GST film.

  3. Photolithographically patterened thin-film multilayer devices of YBa sub 2 Cu sub 3 O sub 7-x

    Energy Technology Data Exchange (ETDEWEB)

    Kingston, J.J.; Wellstood, F.C.; Quan, D.; Clarke, J.

    1990-09-01

    We have fabricated thin-film YBa{sub 2}Cu{sub 3}O{sub 7-x}-SrTiO{sub 3}-YBa{sub 2}Cu{sub 3}O{sub 7-x} multilayer interconnect structures in which each in situ laser-deposited film is independently patterned by photolithography. In particular, we have constructed the two key components necessary for a superconducting multilayer interconnect technology, crossovers and window contacts. As a further demonstration of the technology, we have fabricated a thin-film flux transformer, suitable for use with a Superconducting QUantum Interference Device (SQUID), that includes a ten-turn input coil with 6{mu}m linewidth. Transport measurements showed that the critical temperature was 87K and the critical current was 135 {mu}A at 82K. 7 refs., 6 figs.

  4. Status of Structural Analysis of Substrates and Film Growth Inputs for GaN Device Development Program

    Science.gov (United States)

    2011-01-01

    from 8 scans per 2” sample to 32. Our team has been developing GaN Schottky diodes and HEMTs with segments of these wafers. 12 Figure 7. Ranking...analysis of variance Asym asymmetric x-ray scan CL cathodoluminescence FOM figure of merit FWHM full width at half maximum GaN gallium nitride HEMT ...Status of Structural Analysis of Substrates and Film Growth Inputs for GaN Device Development Program by Kevin Kirchner ARL-TR-5427

  5. Growth of (111)-oriented epitaxial and textured ferroelectric Y-doped HfO2 films for downscaled devices

    Science.gov (United States)

    Katayama, Kiliha; Shimizu, Takao; Sakata, Osami; Shiraishi, Takahisa; Nakamura, Syogo; Kiguchi, Takanori; Akama, Akihiro; Konno, Toyohiko J.; Uchida, Hiroshi; Funakubo, Hiroshi

    2016-09-01

    In this study, the growth of (111)-oriented epitaxial and textured YO1.5-HfO2 (0.07:0.93 ratio) films using the pulsed laser deposition method is presented. Epitaxial films were prepared on ITO//(111)yttria-stabilized zirconia (YSZ) substrates (ITO: Sn-doped In2O3; YSZ: yttria-stabilized zirconia), while textured films were prepared on (111)Pt/TiOx/SiO2//Si substrates with and without an ITO buffer layer via the grain on grain coherent growth. Inserting an ITO layer increased the volume fraction of the ferroelectric orthorhombic phase. Both the epitaxial and uniaxially textured films exhibited similar ferroelectricity with a remanent polarization of around 10 μC/cm2 and a coercive field of 1.9 to 2.0 MV/cm. These results present us with a way of obtaining stable and uniform ferroelectric properties for each grain and device cells consisting of a small number of grains. This opens the door for ultimately miniaturized ferroelectric devices, such as ferroelectric field effect transistors with small gate length and resistive random access memory using ferroelectric tunnel junctions.

  6. Application of photo-doping phenomenon in amorphous chalcogenide GeS2 film to optical device

    Science.gov (United States)

    Murakami, Yoshihisa; Arai, Katsuya; Wakaki, Moriaki; Shibuya, Takehisa; Shintaku, Toshihiro

    2015-03-01

    Photodoping phenomenon is observed when a double-layer consisting of an amorphous chalcogenide film (As2S3, GeS2, GeSe2 etc.) and a metal (Ag, Cu etc.) film is illuminated by light. The metal diffuses abnormally into the amorphous chalcogenide layer. Amorphous chalcogenide films of GeS2 with an Ag over layer exhibited large increase of refractive index through the abnormal doping of Ag by irradiating the light around the absorption edge of the GeS2 chalcogenide. In this study, we aimed the application of this effect for the fabrication of optical devices and fabricated various micro doped patterns by using a laser beam. Mask less pattering with refractive index modified films are possible by manipulating the scanning of the laser beam. Micro gratings were fabricated using a confocal laser microscope to work as both fabrication and observation system. Waveguides were also fabricated by scanning the laser beam for photodoping. Holographic gratings were fabricated by utilizing the photodoping of the two beam interference pattern, which showed the possibility to produce large scale optical devices or mass production.

  7. Polycrystalline thin film materials and devices. Annual subcontract report, 16 January 1990--15 January 1991

    Energy Technology Data Exchange (ETDEWEB)

    Baron, B.N.; Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E. [Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion

    1991-11-01

    Results and conclusion of Phase I of a multi-year research program on polycrystalline thin film solar cells are presented. The research comprised investigation of the relationships among processing, materials properties and device performance of both CuInSe{sub 2} and CdTe solar cells. The kinetics of the formation of CuInSe{sub 2} by selenization with hydrogen selenide was investigated and a CuInSe{sub 2}/CdS solar cell was fabricated. An alternative process involving the reaction of deposited copper-indium-selenium layers was used to obtain single phase CuInSe{sub 2} films and a cell efficiency of 7%. Detailed investigations of the open circuit voltage of CuInSe{sub 2} solar cells showed that a simple Shockley-Read-Hall recombination mechanism can not account for the limitations in open circuit voltage. Examination of the influence of CuInSe{sub 2} thickness on cell performance indicated that the back contact behavior has a significant effect when the CuInSe{sub 2} is less than 1 micron thick. CdTe/CdS solar cells with efficiencies approaching 10% can be repeatedly fabricated using physical vapor deposition and serial post deposition processing. The absence of moisture during post deposition was found to be critical. Improvements in short circuit current of CdTe solar cells to levels approaching 25 mA/cm{sup 2} are achievable by making the CdS window layer thinner. Further reductions in the CdS window layer thickness are presently limited by interdiffusion between the CdS and the CdTe. CdTe/CdS cells stored without protection from the atmosphere were found to degrade. The degradation was attributed to the metal contact. CdTe cells with ZnTe:Cu contacts to the CdTe were found to be more stable than cells with metal contacts. Analysis of current-voltage and spectral response of CdTe/CdS cells indicates the cell operates as a p-n heterojunction with the diode current dominated by SRH recombination in the junction region of the CdTe.

  8. Characterization of solution structure and its importance in thin film ordering of conjugated block copolymers for organic semiconductor devices

    Science.gov (United States)

    Brady, Michael; Ku, Sung-Yu; Cochran, Justin; Wang, Cheng; Hawker, Craig; Kramer, Edward; Chabinyc, Michael

    2014-03-01

    Fully conjugated diblock copolymers (CBCPs) form intriguing materials alternatives to polymer-small molecule blends for their control of mesoscopic order in low-cost organic semiconductor devices. In both bulk heterojunction (BHJ) photovoltaics, consisting of an interpenetrating network with high donor-acceptor interfacial area, and ambipolar transistors, the transport of charge carriers through continuous p- and n-type paths in thin films is a controlling factor in device performance. AFM, GIWAXS, NEXAFS spectroscopy, and RSoXS are used to probe the structure of films of CBCPs with a p-type P3HT block and an n-type DPP block. Thermal annealing in the P3HT melt after casting creates ordered domains with ~ 50 nm in-plane lamellar spacings, as confirmed with GISAXS and RSoXS. GIWAXS diffraction from the (h00) alkyl-stacking and (010) pi-stacking planes shows primarily edge-on orientation for crystals of both P3HT and DPP blocks. In addition, temperature-dependent solution SAXS and UV-Vis spectroscopy are used to probe the size and conformation of casting solution aggregates. Fibrillar DPP aggregates direct the crystallization of P3HT- b-DPP following film casting and enable the formation of wormlike domains after annealing and thus ideal morphologies for transport in organic devices.

  9. High-rate production of functional nanostructured films and devices by coupling flame spray pyrolysis with supersonic expansion.

    Science.gov (United States)

    Wegner, K; Vinati, S; Piseri, P; Antonini, A; Zelioli, A; Barborini, E; Ducati, C; Milani, P

    2012-05-11

    The fabrication of functional thin films and devices by direct deposition of nanoparticles from the gas phase is a promising approach enabling, for instance, the integration of complex analytical and sensing capabilities on microfabricated platforms. Aerosol-based techniques ensure large-scale nanoparticle production and they are potentially suited for this goal. However, they are not adequate in terms of fine control over the lateral resolution of the coatings, mild processing conditions (avoiding high temperature and aggressive chemicals), low contamination and compatibility with microfabrication processes. Here we report the high-rate and efficient production of functional nanostructured films by nanoparticle assembling obtained by the combination of flame spray pyrolysis and supersonic expansion. Our approach merges the advantages of flame spray pyrolysis for bulk nanopowders such as process stability and wide material library availability with those of supersonic cluster beam deposition in terms of lateral resolution and of direct integration of nanomaterials on devices. We efficiently produced nanostructured films and devices (such as gas sensors) using metal oxide, pure noble metal and oxide-supported noble metal nanoparticles.

  10. Light trapping in thin film solar cells using photonic engineering device concepts

    Science.gov (United States)

    Mutitu, James Gichuhi

    In this era of uncertainty concerning future energy solutions, strong reservations have arisen over the continued use and pursuit of fossil fuels and other conventional sources of energy. Moreover, there is currently a strong and global push for the implementation of stringent measures, in order to reduce the amount of green house gases emitted by every nation. As a consequence, there has emerged a sudden and frantic rush for new renewable energy solutions. In this world of renewable energy technologies is where we find photovoltaic (PV) technology today. However, as is, there are still many issues that need to be addressed before solar energy technologies become economically viable and available to all people, in every part of the world. This renewed interest in the development of solar electricity, has led to the advancement of new avenues that address the issues of cost and efficiency associated with PV. To this end, one of the prominent approaches being explored is thin film solar cell (TFSC) technology, which offers prospects of lower material costs and enables larger units of manufacture than conventional wafer based technology. However, TFSC technologies suffer from one major problem; they have lower efficiencies than conventional wafer based solar cell technologies. This lesser efficiency is based on a number of reasons, one of which is that with less material, there is less volume for the absorption of incident photons. This shortcoming leads to the need for optical light trapping; which is concerned with admitting the maximum amount of light into the solar cell and keeping the light within the structure for as long as possible. In this thesis, I present the fundamental scientific ideas, practice and methodology behind the application of photonic engineering device concepts to increase the light trapping capacity of thin film solar cells. In the introductory chapters, I develop the basic ideas behind light trapping in a sequential manner, where the effects

  11. Physical properties of ultrafast deposited micro- and nanothickness amorphous hydrogenated carbon films for medical devices and prostheses.

    Science.gov (United States)

    Zaharia, T; Sullivan, I L; Saied, S O; Bosch, R C; Bijker, M D

    2007-02-01

    Hydrogenated amorphous carbon films with diamond-like structures have been formed on different substrates at very low energies and temperatures by a plasma-enhanced chemical vapour deposition (PECVD) process employing acetylene as the precursor gas. The plasma source was of a cascaded arc type with argon as the carrier gas. The films grown at very high deposition rates were found to have a practical thickness limit of approximately 1.5 microm, above which delamination from the substrate occurred. Deposition on silicon (100), glass, and plastic substrates has been studied and the films characterized in terms of sp3 content, roughness, hardness, adhesion, and optical properties. Deposition rates of up to 20 nm/s have been achieved at substrate temperatures below 100 degrees C. A typical sp3 content of 60-75 per cent in the films was determined by X-ray-generated Auger electron spectroscopy (XAES). The hardness, reduced modulus, and adhesion of the films were measured using a MicroMaterials NanoTest indenter/scratch tester. Hardness was found to vary from 4 to 13 GPa depending on the admixed acetylene flow and substrate temperature. The adhesion of the film to the substrate was significantly influenced by the substrate temperature and whether an in situ d.c. cleaning was employed prior to the deposition process. The hydrogen content in the film was measured by a combination of the Fourier transformation infrared (FTIR) spectroscopy and Rutherford backscattering (RBS) techniques. From the results it is concluded that the films formed by the process described here are ideal for the coating of long-term implantable medical devices, such as prostheses, stents, invasive probes, catheters, biosensors, etc. The properties reported in this publication are comparable with good-quality films deposited by other PECVD methods. The advantages of these films are the low ion energy and temperature of deposition, ensuring that no damage is done to sensitive substrates, very high

  12. Electrochromism of non-stoichiometric NiO thin film: as single layer and in full device

    Science.gov (United States)

    Da Rocha, M.; Rougier, A.

    2016-04-01

    Electrochromic properties, known as a reversible modulation of the optical properties under an applied voltage, of NiO thin films are discussed in respect of the film stoichiometry. Using radio-frequency magnetron sputtering, non-stoichiometric "NiO" thin films of good crystallinity were grown at room temperature from low oxygen partial pressure [i.e., above 2 % P(O2/Ar + O2)]. A further increase in oxygen partial pressure leads to conductive brownish films containing a large amount of Ni3+. 2 %-Ni1- x O thin films exhibit significant EC performance in lithium-based electrolyte with a transmittance modulation of 25 %. If it is generally accepted that this optical modulation is due to an insertion of small cations, the presence of additional surface phenomena is also shown. The cycling of full device, based on the association of WO3 and "NiO" in temperature up to 60 °C and down to -35 °C confirms expected increase and decrease in capacity while surprisingly the optical switch from a transparent to a neutral gray color appears slightly modified.

  13. Investigations on nonlinear optical properties of electron beam treated Gd:ZnO thin films for photonic device applications

    Science.gov (United States)

    Spoorthi, K.; Pramodini, S.; Kityk, I. V.; Abd-Lefdil, M.; Sekkati, M.; El Fakir, A.; Rao, Ashok; Sanjeev, Ganesh; Poornesh, P.

    2017-06-01

    In this article, we report the third-order nonlinear optical properties of electron beam irradiated gadolinium-doped zinc oxide (GZO) thin films prepared using the spray pyrolysis deposition technique. GZO thin films were treated with an electron beam from a variable energy microtron accelerator at dose rates ranging from 1-5 kGy. Nonlinear optical measurements were conducted by employing the single beam Z-scan technique. A continuous wave He-Ne laser operating at 633 nm was used as the source of excitation. Closed aperture Z-scan results reveal that the films exhibit self-defocusing nonlinearity. Open aperture Z-scan results exhibit a switching over phenomena of reverse saturable absorption to saturable absorption for thin film irradiated at 3 kGy, indicating the influence of electron beams on optical nonlinearity. The significant change in third-order nonlinear optical susceptibility χ (3) ranging from 2.14  ×  10-3 to 3.12  ×  10-3 esu is attributed to the effect of electron beam irradiation. The study shows that the nonlinear coefficients of GZO films can be tuned by electron beams for use in nonlinear optical device applications.

  14. Fabrication and Optimization of Brush-Printed n-type Bi2Te3 Thick Films for Thermoelectric Cooling Devices

    Science.gov (United States)

    Liu, Xing; Zhao, Wen-yu; Zhou, Hong-yu; Mu, Xin; He, Dan-qi; Zhu, Wan-ting; Wei, Ping; Wu, Han; Zhang, Qing-jie

    2016-03-01

    A simple, efficient and rapid brush-printing method has been developed for preparation of n-type Bi2Te2.7Se0.3 films approximately 100-150 μm thick. X-ray diffraction, scanning electron microscopy, electron probe microanalysis, and four-point probe measurements were used to characterize the crystal structure, composition, microstructure, and electrical properties of the films. The results showed that all the n-type Bi2Te2.7Se0.3 thick films were composed of single-phase Bi2Te2.7Se0.3; the grains in the films were randomly distributed in the low-temperature-annealed samples and predominantly oriented along the (00 l) plane in samples annealed at temperatures >673 K. σ and the absolute value of α first increased substantially with increasing the annealing temperature in the range 573-673 K then decreased when the annealing temperature was increased further. The dependence of σ and α on annealing temperature may be reasonably explained on the basis of the change in the microstructure induced by annealing. The performance of a prototype cooling device containing n-type Bi2Te2.7Se0.3 thick films was evaluated for temperature differences produced by use of different DC currents.

  15. An anode with aluminum doped on zinc oxide thin films for organic light emitting devices [rapid communication

    Science.gov (United States)

    Xu, Denghui; Deng, Zhenbo; Xu, Ying; Xiao, Jing; Liang, Chunjun; Pei, Zhiliang; Sun, Chao

    2005-10-01

    Doped zinc oxides are attractive alternative materials as transparent conducting electrode because they are nontoxic and inexpensive compared with indium tin oxide (ITO). Transparent conducting aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by DC reactive magnetron sputtering method. Films were deposited at a substrate temperature of 150 °C in 0.03 Pa of oxygen pressure. The electrical and optical properties of the film with the Al-doping amount of 2 wt% in the target were investigated. For the 300-nm thick AZO film deposited using a ZnO target with an Al content of 2 wt%, the lowest electrical resistivity was 4×10Ωcm and the average transmission in the visible range 400 700 nm was more than 90%. The AZO film was used as an anode contact to fabricate organic light-emitting diodes. The device performance was measured and the current efficiency of 2.9 cd/A was measured at a current density of 100 mA/cm2.

  16. Effects of Controlling the AZO Thin Film's Optical Band Gap on AZO/MEH-PPV Devices with Buffer Layer

    Directory of Open Access Journals (Sweden)

    Jaehyoung Park

    2012-01-01

    Full Text Available Organic/inorganic hybrid solar cells were fabricated incorporating aluminum-doped zinc oxide (AZO thin films of varying optical band gap in AZO/poly(2-methoxy-5-(2′-ethyl-hexyloxy-p-phenylene vinylene structures. The band gaps were controlled by varying the flow rates of Ar and O2 used to deposit the AZO. Devices with CdS buffer layer were also fabricated for improved efficiency. The effects of AZO optical band gap were assessed by testing the I–V characteristics of devices with structures of glass/ITO/AZO/MEH-PPV/Ag under AM1.5 illumination (100 mW/cm2. Efficiency was improved about 30 times by decreasing the AZO optical band gap, except in devices deposited without oxygen. A power conversion efficiency of 0.102% was obtained with the incorporation of a CdS buffer layer.

  17. Microstructure of titanium nitride thin films controlled by ion bombardment in a magnetron-sputtering device

    Energy Technology Data Exchange (ETDEWEB)

    Cerny, R. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Kuzel, R. Jr. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Valvoda, V. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Kadlec, S. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics); Musil, J. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics)

    1994-05-01

    The structure of titanium nitride thin films deposited by unbalanced magnetron sputtering on high chromium steel substrates was studied by X-ray diffraction. In order to characterize relations between the microstructure of sputtered TiN films and the deposition conditions, the parameter E[sub p] was introduced as the average energy transmitted from bombarding particles (ions, electrons, neutrals, photons) to one condensing particle of the film. A transition from a porous to a compact microstructure was found with increasing E[sub p]. The possible inhomogeneity of titanium nitride films is discussed. (orig.)

  18. Effects of bacteria on CdS thin films used in technological devices

    Science.gov (United States)

    Alpdoğan, S.; Adıgüzel, A. O.; Sahan, B.; Tunçer, M.; Metin Gubur, H.

    2017-04-01

    Cadmium sulfide (CdS) thin films were fabricated on glass substrates by the chemical bath deposition method at 70 {}^\\circ \\text{C} considering deposition times ranging from 2 h to 5 h. The optical band gaps of CdS thin films were found to be in the 2.42-2.37 eV range. CdS thin films had uniform spherical nano-size grains which had polycrystalline, hexagonal and cubic phases. The films had a characteristic electrical resistivity of the order of {{10}5} Ω \\text{cm} and n-type conductivity at room condition. CdS thin films were incubated in cultures of B.domonas aeruginosa and Staphylococcus aureus, which exist abundantly in the environment, and form biofilms. SEM images showed that S. aureus and K. pneumonia were detected significantly on the film surfaces with a few of P. aeruginosa and B. subtilis cells attached. CdS thin film surface exhibits relatively good resistance to the colonization of P. aeruginosa and B. subtilis. Optical results showed that the band gap of CdS thin films which interacted with the bacteria is 2.42 \\text{eV} . The crystal structure and electrical properties of CdS thin films were not affected by bacterial adhesion. The antimicrobial effect of CdS nanoparticles was different for different bacterial strains.

  19. In-situ spectroscopy and nanoscale electronics in superconductor-topological insulator hybrid devices: a combined thin film growth and quantum transport study

    NARCIS (Netherlands)

    Ngabonziza, Prosper

    2016-01-01

    In this dissertation, we presented a combined thin film growth and quantum transport study on superconductor topological insulator hybrid devices. Understanding of the electronic properties of topological insulators (TIs), their preparation in high quality thin film form and their interaction with o

  20. Optimization of PEDOT films in ionic liquid supercapacitors: demonstration as a power source for polymer electrochromic devices.

    Science.gov (United States)

    Österholm, Anna M; Shen, D Eric; Dyer, Aubrey L; Reynolds, John R

    2013-12-26

    We report on the optimization of the capacitive behavior of poly(3,4-ethylenedioxythiophene) (PEDOT) films as polymeric electrodes in flexible, Type I electrochemical supercapacitors (ESCs) utilizing ionic liquid (IL) and organic gel electrolytes. The device performance was assessed based on figures of merit that are critical to evaluating the practical utility of electroactive polymer ESCs. PEDOT/IL devices were found to be highly stable over hundreds of thousands of cycles and could be reversibly charged/discharged at scan rates between 500 mV/s and 2 V/s depending on the polymer loading. Furthermore, these devices exhibit leakage currents and self-discharge rates that are comparable to state of the art electrochemical double-layer ESCs. Using an IL as device electrolyte allowed an extension of the voltage window of Type I ESCs by 60%, resulting in a 2.5-fold increase in the energy density obtained. The efficacies of tjese PEDOT ESCs were assessed by using them as a power source for a high-contrast and fast-switching electrochromic device, demonstrating their applicability in small organic electronic-based devices.

  1. High performance AlScN thin film based surface acoustic wave devices with large electromechanical coupling coefficient

    Science.gov (United States)

    Wang, Wenbo; Mayrhofer, Patrick M.; He, Xingli; Gillinger, Manuel; Ye, Zhi; Wang, Xiaozhi; Bittner, Achim; Schmid, Ulrich; Luo, J. K.

    2014-09-01

    AlN and AlScN thin films with 27% scandium (Sc) were synthesized by DC magnetron sputtering deposition and used to fabricate surface acoustic wave (SAW) devices. Compared with AlN-based devices, the AlScN SAW devices exhibit much better transmission properties. Scandium doping results in electromechanical coupling coefficient, K2, in the range of 2.0% ˜ 2.2% for a wide normalized thickness range, more than a 300% increase compared to that of AlN-based SAW devices, thus demonstrating the potential applications of AlScN in high frequency resonators, sensors, and high efficiency energy harvesting devices. The coupling coefficients of the present AlScN based SAW devices are much higher than that of the theoretical calculation based on some assumptions for AlScN piezoelectric material properties, implying there is a need for in-depth investigations on the material properties of AlScN.

  2. Relating Film Structure/Microstructure on Device Function/Microproperties in Conjugated Polymers and Polymer/Small Molecule Blends

    Science.gov (United States)

    Cochran, Justin Enir

    Over the last twenty years conjugated organic materials, polymers and small molecules, have attracted broad interest due to their potential applications in the field of solution processed low cost electronics. Due to their semi/polycrystalline nature the spatial arrangement of crystallites and disordered regions in the film have a significant influence over charge transport properties. Structure-Function relationships are universal; consequently, the focus of my research thesis is to relate the film structure/microstructure to device performance and micro-properties, specifically in thin film transistors and bulk conductivity measurements. My initial research focus was on how modification of a semiconducting polymers backbone alters the packing structure and in turn impacts device performance. We then focused on how modification of TFT interface microstructures by altering between dielectric surfaces changes the orientaional correlation length in the semiconductors crystalline domains which in turn directly impacts the field effect mobility. The final two projects focused on doping conjugated polymers with small molecular acceptors. The purpose was to understand how bulk packing dominates conductivity in order to better understand what appears to be a universal transport behavior in these blends. These insights into the structural changes provide a platform under which to analyze the electrical measurements where significant changes in conductivity were observed at high acceptor concentrations but results showed dependence upon pre and post processing conditions. As expected, increases in film conductivity scaled with acceptor concentration but of special interest is how the conductivity showed temperature stability upon annealing, even increasing under certain conditions, near the polymer liquid crystal transition temperature and then decreasing below the as cast baseline at higher annealing temperatures. The electrical study combined with the structural analysis

  3. A reversible bipolar WORM device based on AlOxNy thin film with Al nano phase embedded

    Science.gov (United States)

    Zhu, W.; Li, J.; Zhang, L.; Hu, X. C.

    2017-03-01

    An Al-rich AlOxNy thin film based reversible Write-Once-Read-Many-Times (WORM) memory device with MIS structure could transit from high resistance state (HRS, ∼1011 Ω) to low resistance state (LRS, ∼105 Ω) by sweeping voltage up to ∼20 V. The first switching could be recorded as writing process for WORM device which may relate to conductive path are formed through the thin film. The conductive path should be formed by both Al nano phase and oxygen vacancies. Among of them, Al nano phases are not easy to move, but oxygen vacancies could migrate under high E-field or at high temperature environment. Such conductive path is not sensitive to charging effect after it formed, but it could be broken by heating effect, which may relate to the migration of excess Al ions and oxygen vacancies at high temperature. After baking LRS (ON state) WORM device at 200 °C for 2 min, the conductivity will decrease to HRS which indicates conductive path is broken and device back to HRS (OFF state) again. This phenomenon could be recorded as recovery process. Both writing and recovery process related to migration of oxygen vacancies and could be repeated over 10 times in this study. It also indicates that there is no permanent breakdown occurred in MIS structured WORM device operation. We suggest that this conductive path only can be dissolved by a temperature sensitive electro-chemical action. This WORM device could maintain at LRS over 105 s with on-off ratio over 4 orders.

  4. Ferroelectric and piezoelectric properties of epitaxial PZT films and devices on silicon

    NARCIS (Netherlands)

    Nguyen, Minh Duc

    2010-01-01

    In this thesis, the integration of lead zirconate titanate Pb(Zr,Ti)O3 (PZT) thin films into piezoelectric microelectromechanical systems (MEMS) based on silicon is studied. In these structures, all epitaxial oxide layers (thin film/electrode/buffer-layer(s)) were deposited by pulsed laser depositio

  5. Ferroelectric and piezoelectric properties of epitaxial PZT films and devices on silicon

    NARCIS (Netherlands)

    Nguyen, Duc Minh

    2010-01-01

    In this thesis, the integration of lead zirconate titanate Pb(Zr,Ti)O3 (PZT) thin films into piezoelectric microelectromechanical systems (MEMS) based on silicon is studied. In these structures, all epitaxial oxide layers (thin film/electrode/buffer-layer(s)) were deposited by pulsed laser depositio

  6. Resistive switching characteristics and conduction mechanisms of nonvolatile memory devices based on Ga and Sn co-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Dohyun; Yun, Dong Yeol; Lee, Nam Hyun; Kim, Tae Whan, E-mail: twk@hanyang.ac.kr

    2015-07-31

    Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films formed by using a solution process method. X-ray diffraction patterns showed that the crystallinity of the annealed GZTO films was an amorphous phase. X-ray photoelectron spectroscopy spectra of the GZTO films depicted Zn−O, Ga−O, and Sn−O bonds. Current–voltage measurements on the Al/GZTO/indium-tin-oxide (ITO) devices at 300 K showed bipolar resistive switching behaviors. The resistances at both the low resistance state (LRS) and high resistance state (HRS) measured at 0.5 V for the devices maintain almost constant without any damage and breakdown above 130 s, indicative of the memory stability of the devices. A difference in the resistance between the HRS and the LRS was more than 1 order of the magnitude. The conduction mechanisms of the HRS in the set process for the Al/GZTO/ITO devices were dominated by a space-charge-limited current model. - Highlights: • Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films. • X-ray diffraction patterns showed that the annealed GZTO films were an amorphous phase. • Current–voltage measurements on the devices showed bipolar resistive switching behaviors. • One order magnitude difference in resistance between low and high resistance states (HRS) • Space charge limited conduction is the dominant conduction mechanisms of the HRS.

  7. High Growth Rate Deposition of Hydrogenated Amorphous Silicon-Germanium Films and Devices Using ECR-PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yong [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    Hydrogenated amorphous silicon germanium films (a-SiGe:H) and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large-scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert-gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. Preferential attachment of hydrogen to silicon, clustering of Ge and Si, and columnar structure and buried dihydride radicals make the film intolerably bad. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with a small amount of H2, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, I-V curve, and quantum efficiency were characterized during the process of pursuing good materials. The microstructure of the a-(Si,Ge):H material was probed by Fourier-Transform Infrared spectroscopy. They found that the advantages of using helium as the main plasma species are: (1) high growth rate--the energetic helium ions break the reactive gas more efficiently than hydrogen ions; (2) homogeneous growth--heavy helium ions impinging on the surface promote the surface mobility of the reactive radicals, so that heteroepitaxy growth as clustering of Ge and Si, columnar structure are

  8. Multiferroic BiFeO3 thin films for multifunctional devices.

    Science.gov (United States)

    Singh, Manish K; Yang, Yi; Takoudis, Christos G; Tatarenko, A; Srinivasan, G; Kharel, P; Lawes, G

    2010-09-01

    We report the metalorganic chemical vapor deposition of crystalline BiFeO3 films on platinized silicon substrates using n-butylferrocene, triphenylbismuth and oxygen. Based on thermogravimetric analysis data, the suitability of these two precursors for depositing BiFeO3 is discussed. The deposited films were characterized for structure and morphology using X-ray diffraction and scanning electron microscopy. Composition analysis using X-ray photoelectron spectroscopy revealed that the films were stoichiometric BiFeO3. Electrostatic force microscopy indicated that the film had polarizable domains that showed no deterioration in polarization over time long after electric poling. The film showed a saturation magnetization of 10 +/- 1 emu/cm3 at room temperature.

  9. Reactive Sputter Deposition of WO3/Ag/WO3 Film for Indium Tin Oxide (ITO)-Free Electrochromic Devices.

    Science.gov (United States)

    Yin, Yi; Lan, Changyong; Guo, Huayang; Li, Chun

    2016-02-17

    Functioning both as electrochromic (EC) and transparent-conductive (TC) coatings, WO3/Ag/WO3 (WAW) trilayer film shows promising potential application for ITO-free electrochromic devices. Reports on thermal-evaporated WAW films revealed that these bifunctional WAW films have distinct EC characteristics; however, their poor adhesive property leads to rapid degradation of coloring-bleaching cycling. Here, we show that WAW film with improved EC durability can be prepared by reactive sputtering using metal targets. We find that, by introducing an ultrathin tungsten (W) sacrificial layer before the deposition of external WO3, the oxidation of silver, which leads to film insulation and apparent optical haze, can be effectively avoided. We also find that the luminous transmittance and sheet resistance were sensitive to the thicknesses of tungsten and silver layers. The optimized structure for TC coating was obtained to be WO3 (45 nm)/Ag (10 nm)/W (2 nm)/WO3 (45 nm) with a sheet resistance of 16.3 Ω/□ and a luminous transmittance of 73.7%. Such film exhibits compelling EC performance with decent luminous transmittance modulation ΔTlum of 29.5%, fast switching time (6.6 s for coloring and 15.9 s for bleaching time), and long-term cycling stability (2000 cycles) with an applied potential of ±1.2 V. Thicker external WO3 layer (45/10/2/100 nm) leads to larger modulation with maximum ΔTlum of 46.4%, but at the cost of significantly increasing the sheet resistance. The strategy of introducing ultrathin metal sacrificial layer to avoid silver oxidation could be extended to fabricating other oxide-Ag-oxide transparent electrodes via low-cost reactive sputtering.

  10. A Digital Badging Dataset Focused on Performance, Engagement and Behavior-Related Variables from Observations in Web-Based University Courses

    Science.gov (United States)

    McDaniel, Rudy; Fanfarelli, Joseph R.

    2015-01-01

    This dataset contains participant data related to the use of badging (achievement) feedback in pedagogical design. Two sections each of web-based graphic design and web design undergraduate courses were offered at the University of Central Florida. A badging system for achievements was included in one section of each. Performance, engagement and…

  11. Environmental Science and Engineering Merit Badges: An Exploratory Case Study of a Non-Formal Science Education Program and the U.S. Scientific and Engineering Practices

    Science.gov (United States)

    Vick, Matthew E.; Garvey, Michael P.

    2016-01-01

    The Boy Scouts of America's Environmental Science and Engineering merit badges are two of their over 120 merit badges offered as a part of a non-formal educational program to U.S. boys. The Scientific and Engineering Practices of the U.S. Next Generation Science Standards provide a vision of science education that includes integrating eight…

  12. The effects of radiation damage on power VDMOS devices with composite SiO2-Si3N4 films

    Institute of Scientific and Technical Information of China (English)

    Gao Bo; Liu Gang; Wang Li-Xin; Han Zheng-Sheng; Song Li-Mei; Zhang Yan-Fei; Teng Rui

    2013-01-01

    Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor (VDMOS) devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.

  13. Photochemical solution processing of films of metastable phases for flexible devices: the β-Bi2O3 polymorph

    Science.gov (United States)

    Pérez-Mezcua, Dulce; Bretos, Iñigo; Jiménez, Ricardo; Ricote, Jesús; Jiménez-Rioboó, Rafael J.; da Silva, Cosmelina Gonçalves; Chateigner, Daniel; Fuentes-Cobas, Luis; Sirera, Rafael; Calzada, M. Lourdes

    2016-12-01

    The potential of UV-light for the photochemical synthesis and stabilization of non-equilibrium crystalline phases in thin films is demonstrated for the β-Bi2O3 polymorph. The pure β-Bi2O3 phase is thermodynamically stable at high temperature (450–667 °C), which limits its applications in devices. Here, a tailored UV-absorbing bismuth(III)-N-methyldiethanolamine complex is selected as an ideal precursor for this phase, in order to induce under UV-light the formation of a –Bi–O–Bi– continuous network in the deposited layers and the further conversion into the β-Bi2O3 polymorph at a temperature as low as 250 °C. The stabilization of the β-Bi2O3 films is confirmed by their conductivity behavior and a thorough characterization of their crystal structure. This is also supported by their remarkable photocatalytic activity. Besides, this processing method has allowed us for the first time the preparation of β-Bi2O3 films on flexible plastic substrates, which opens new opportunities for using these materials in potential applications not available until now (e.g., flexible photocatalytic reactors, self-cleaning surfaces or wearable antimicrobial fabrics). Therefore, photochemical solution deposition (PCSD) demonstrates to be not only an efficient approach for the low temperature processing of oxide films, but also an excellent alternative for the stabilization of metastable phases.

  14. Designing Single Chamber Hwcvd System for High Deposition Rate Device Quality A-Si:h Thin Films and Solar Cells

    Directory of Open Access Journals (Sweden)

    N.A. Wadibhasme

    2011-01-01

    Full Text Available A new single chamber HWCVD with vertically mounted substrates and filaments has been designed for depositing device quality a-Si:H films with high deposition rate. Optimization studies on films deposited in this chamber under a variety of deposition conditions yielded uniform films at more than 7Å/sec deposition rate and with very low oxygen content. These films show a photoconductivity gain of more than 105. The working pressure has been kept quite low at 15 mtorr compared to earlier studies. i-layers of a p-i-n single junction solar cells were deposited on the TCO (Asahi-U type glass in this reactor. The initial p-layer and the final n-layer were deposited in another system with separate chambers for these doped layers thus exposing the p-layer as well as the i-layer to the atmosphere during the transfer. Using this optimized intrinsic layer, a-Si:H based p-i-n solar cell showed a conversion efficiency of 4.7 %.

  15. Feasibility Study on Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Inha

    2013-12-15

    This report on the 'Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation' is belonged to the final report on the preliminary study of the first subject in 2013 for civilian project. This was complimented on the responsible of the Korea Atomic Energy Research Institute for 1{sup st} of June 2013 to 30{sup th} of November 2013. We are going to make sterilization the badge using the gamma ray and supplying the oxygen by nano-bubble oxygen rich water for cultivating the Matsutake Mushroom, instead of the conventional process of sterilization of the badge by hot steam over 120 .deg. C consuming over 8 hours and expensive ventilation system for supplying the fresh air for delivering the oxygen.

  16. Nano-gold assisted highly conducting and biocompatible bacterial cellulose-PEDOT:PSS films for biology-device interface applications.

    Science.gov (United States)

    Khan, Shaukat; Ul-Islam, Mazhar; Ullah, Muhammad Wajid; Israr, Muhammad; Jang, Jae Hyun; Park, Joong Kon

    2017-09-18

    This study reports the fabrication of highly conducting and biocompatible bacterial cellulose (BC)-gold nanoparticles (AuNPs)-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) (BC-AuNPs-PEDOT:PSS) composites for biology-device interface applications. The composites were fabricated using ex situ incorporation of AuNPs and PEDOT:PSS into the BC matrix. Structural characterization, using scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD) analysis, confirmed the uniform nature of the synthesized BC-AuNPs and BC-AuNPs-PEDOT:PSS composites. Four-point probe analysis indicated that the BC-AuNPs and BC-AuNPs-PEDOT:PSS films had high electrical conductivity. The composites were also tested for biocompatibility with animal osteoblasts (MC3T3-E1). The composite films supported adhesion, growth, and proliferation of MC3T3-E1 cells, indicating that they are biocompatible and non-cytotoxic. AuNPs and PEDOT:PSS, imparted a voltage response, while BC imparted biocompatibility and bio-adhesion to the nanocomposites. Therefore, our BC-AuNPs-PEDOT:PSS composites are candidate materials for biology-device interfaces to produce implantable devices in regenerative medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Performance enhancement of ZnS:Mn thin film electroluminescent devices by combination of laser and thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Koutsogeorgis, Demosthenes C., E-mail: demosthenes.koutsogeorgis@ntu.ac.u [School of Science and Technology, Displays Research Group, Nottingham Trent University, Nottingham NG11 8NS (United Kingdom); Cranton, Wayne M.; Ranson, Robert M.; Thomas, Clive B. [School of Science and Technology, Displays Research Group, Nottingham Trent University, Nottingham NG11 8NS (United Kingdom)

    2009-08-26

    The combination of laser and thermal annealing was investigated as a post-deposition process for enhancing the luminescent properties of RF-magnetron sputtered ZnS:Mn thin film electroluminescent devices (TFEL). Laser annealing of the uncoated phosphor layer was performed using KrF excimer 248 nm laser pulses of 20 ns under an argon overpressure of 10 bar to limit laser ablation. Single, double and triple irradiation was applied at 1.4 J/cm{sup 2}. Thermal annealing was performed in vacuum at 500 deg. C and 550 deg. C for 1 h. In this paper we are reporting the brightness-voltage characteristics of devices that have been subjected to all combinations of the two annealing techniques (i.e. laser, thermal, laser + thermal, thermal + laser and finally non-annealed devices). Also, a simple lifetime comparison is made between the best performing device (laser + thermal) and the industrial standard (thermal). The lifetime (time to half brightness) and brightness of the best performing device is found to be more than double compared to the industrial standard.

  18. Symbolic Images of Colors, Animals and Machines in The Red Badge of Courage

    Institute of Scientific and Technical Information of China (English)

    王晓俊

    2014-01-01

    Stephen Crane was an outstanding American novelist, poet, and journalist. He achieved great success in his literary works during his brief career. Crane’s most well-known work, The Red Badge of Courage, is commonly believed to be the first great novel of the American Civil War, largely because of its vivid and detailed description of the experience of warfare. This paper analyzes the images of color, animal and machine, which convey Crane’s thoughts of war: war is full of chaos, brutality, and confusion, without any romantic elements or heroism.

  19. Chemical vapor deposition and characterization of polysilanes polymer based thin films and their applications in compound semiconductors and silicon devices

    Science.gov (United States)

    Oulachgar, El Hassane

    As the semiconductors industry is moving toward nanodevices, there is growing need to develop new materials and thin films deposition processes which could enable strict control of the atomic composition and structure of thin film materials in order to achieve precise control on their electrical and optical properties. The accurate control of thin film characteristics will become increasingly important as the miniaturization of semiconductor devices continue. There is no doubt that chemical synthesis of new materials and their self assembly will play a major role in the design and fabrication of next generation semiconductor devices. The objective of this work is to investigate the chemical vapor deposition (CVD) process of thin film using a polymeric precursor as a source material. This process offers many advantages including low deposition cost, hazard free working environment, and most importantly the ability to customize the polymer source material through polymer synthesis and polymer functionalization. The combination between polymer synthesis and CVD process will enable the design of new generation of complex thin film materials with a wide range of improved chemical, mechanical, electrical and optical properties which cannot be easily achieved through conventional CVD processes based on gases and small molecule precursors. In this thesis we mainly focused on polysilanes polymers and more specifically poly(dimethylsilanes). The interest in these polymers is motivated by their distinctive electronic and photonic properties which are attributed to the delocalization of the sigma-electron along the Si-Si backbone chain. These characteristics make polysilane polymers very promising in a broad range of applications as a dielectric, a semiconductor and a conductor. The polymer-based CVD process could be eventually extended to other polymer source materials such as polygermanes, as well as and a variety of other inorganic and hybrid organic-inorganic polymers

  20. Development of Novel Magnetic Metal Oxide Films and Carbon Nanotube Materials for Magnetic Device Applications

    Science.gov (United States)

    2015-01-23

    epitaxial cobalt ferrite thin films, Phys. Rev. B 76, 054405 (2007). 5. J-P Zhou, H-C He, and C-W Nan, Effects of substrate temperature and oxygen ...report on low 20 temperature magnetization and torque studies on out tri-layered Spin Spring Films. In order to enhance the observed spin effect , we...Korey Pough , Abebe Kebede, Dereje Seifu, Destenie Knock . Magnetic Properties of Iron Chalcogenide Superconducting Materials for Energy Storage

  1. Horizontally-connected ZnO-graphene hybrid films for multifunctional devices

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Yi Rang [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong Post Office Box 107, Daejeon 305-600 (Korea, Republic of); School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Song, Wooseok; Lee, Young Bum; Kim, Seong Ku; Han, Jin Kyu; Myung, Sung; Lee, Sun Sook; An, Ki-Seok [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong Post Office Box 107, Daejeon 305-600 (Korea, Republic of); Choi, Chel-Jong [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Lim, Jongsun, E-mail: jslim@krict.re.kr [Thin Film Materials Research Center, Korea Research Institute of Chemical Technology, Yuseong Post Office Box 107, Daejeon 305-600 (Korea, Republic of)

    2016-08-30

    Highlights: • We designed horizontally-connected ZnO and graphene hybrid nanofilms with improved flexibility for multifunctional nanodevices including high performance TFTs. • The photocurrent on-off ratio, response time, and recovery time of the hybrid photodetectors were estimated to be 10{sup 2}, 34 s, and 27 s, respectively. The photocurrent from the hybrid photodetector decreased only by two-fold, whereas a significant decrease in photocurrent by two orders of magnitude was observed from the ZnO thin film based photodetectors after 10{sup 5} cycles of 5-mm radius bending. • The hybrid thin film transistors exhibited unipolar n-channel transistor behavior with electron mobility of 68.7 cm{sup 2}/V s and on-off ratio of 10{sup 7}. - Abstract: Here we designed horizontally-connected ZnO thin films and graphene in order to combine advantages of ZnO thin films, which are high on/off ratio and photo responsivity, and the superior mobility and sensitivity of graphene for applications in thin film transistors (TFTs) and flexible photodetectors. To synthesize the ZnO/graphene hybrid films, a 70-nm-thick ZnO thin film with a uniformly flat surface deposited by the atomic layer deposition process was horizontally connected with highly crystalline monolayer graphene grown by thermal chemical vapor deposition. The photocurrent on-off ratio, response time, and recovery time of the hybrid photodetectors were estimated to be 10{sup 2}, 34 s, and 27 s, respectively. The photocurrent from the hybrid photodetector decreased only by two-fold, whereas a significant decrease in photocurrent by two orders of magnitude was observed from the ZnO thin film based photodetectors after 10{sup 5} cycles of 5-mm radius bending. The hybrid TFT exhibited unipolar n-channel transistor behavior with electron mobility of 68.7 cm{sup 2}/V s and on-off ratio of 10{sup 7}.

  2. Permalloy Film Array Spin Dynamics and High Performance Integrated Microwave Devices

    Science.gov (United States)

    2008-09-25

    new method for high-frequency characterization of patterned ferromagnetic thin films,” submitted to Journal of Applied Physics . (d) Manuscripts Number...characterization  of  patterned  ferromagnetic thin films,” submitted to  Journal   of   Applied   Physics .   iii. Hanqiao  Zhang,  Chunrong  Song  and

  3. The Evolution of Thin-Film Structure in pi-Conjugated System: Implications for Devices

    Science.gov (United States)

    2015-07-09

    Having demonstrated that semiconductor blends facilitate formation of charge transport pathways in conjugated polymers, we extended our study of blends...component comprises only 5 wt% of the film can preserve the excellent charge carrier transport characteristics of the parent semiconductor allows us to...and during the film formation process. These interactions are the antecedent to the - stacked networks that are crucial for charge transport . In situ

  4. Development of CdSe thin films for application in electronic devices

    OpenAIRE

    Olusola, O. I.; O. K. Echendu; Dharmadasa, I

    2015-01-01

    Thin films of cadmium selenide (CdSe) have been deposited on fluorine-doped tin oxide (FTO)-coated glass using potentiostatic electrodeposition method. The suitable range of deposition potentials for the formation of stoichiometric layer of CdSe was established using cyclic voltammograms. The films have been characterised using X-ray diffraction (XRD), Raman spectroscopy, optical absorption, scanning electron microscopy, atomic force microscopy and photo-electrochemical (PEC) cell techniques....

  5. Preparation of free-standing diamond films for high frequency SAW devices

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-min; XIA Yi-ben; WANG Lin-jun; SU Qing-feng; ZHAO Ping; XU Run; PENG Hong-yan; SHI Wei-min

    2006-01-01

    Free-standing diamond films were prepared by hot filament chemical vapor deposition (HFCVD) method under different conditions. Inter-digital transducers (IDTs) were formed on the nucleation sides of free-standing diamond films by photolithography technique. Then piezoelectric ZnO films were deposited by radio-frequency(RF) reactive magnetron sputtering to obtain the ZnO/diamond film structures. Surface morphologies of the nucleation sides and the IDTs were characterized by means of scanning electron microscopy (SEM),atomic force microscope (AFM) and optical microscopy. The results indicate that the surfaces of nucleation sides are very smooth and the IDTs are of high quality without discontinuity and short circuit phenomenon. Raman spectra show the sharp diamond feature peak at about 1 334 cm-1 and the small amount of non-diamond carbon in the nucleation side. X-ray diffraction (XRD) patterns of the structure of ZnO/diamond films show a strong diffraction peak of ZnO (002),which indicates that as-sputtered ZnO films are highly c-axis oriented.

  6. Ellipsometric Characterization of Thin Films from Multicomponent Chalcogenide Glasses for Application in Modern Optical Devices

    Directory of Open Access Journals (Sweden)

    R. Todorov

    2013-01-01

    Full Text Available A review is given on the application of the reflectance ellipsometry for optical characterization of bulk materials and thin films with thickness between λ/20 and 2λ (at λ=632.8 nm. The knowledge of the optical constants (refractive index, n, and extinction coefficient, k of thin films is of a great importance from the point of view of modelling and controlling the manufacture of various optical elements, such as waveguides, diffraction gratings, and microlenses. The presented results concern the optical properties of thin films from multicomponent chalcogenide glasses on the base of As2S3 and GeS2 determined by multiple-angle-of-incidence ellipsometry and regarded as a function of the composition and thickness. The homogeneity of the films is verified by applying single-angle calculations at different angles. Due to decomposition of the bulk glass during thermal evaporation, an optical inhomogeneity of the thin As (Ge-S-Bi(Tl films is observed. The profile of n in depth of thin As-S-Tl (Bi films was investigated by evaporation of discrete layers. It is demonstrated that homogenous layers from the previous compounds with controlled composition can be deposited by coevaporation of As2S3 and metals or their compounds (Bi, Tl, In2S3.

  7. Thin film complementary metal oxide semiconductor (CMOS) device using a single-step deposition of the channel layer

    KAUST Repository

    Nayak, Pradipta K.

    2014-04-14

    We report, for the first time, the use of a single step deposition of semiconductor channel layer to simultaneously achieve both n-and p-type transport in transparent oxide thin film transistors (TFTs). This effect is achieved by controlling the concentration of hydroxyl groups (OH-groups) in the underlying gate dielectrics. The semiconducting tin oxide layer was deposited at room temperature, and the maximum device fabrication temperature was 350C. Both n and p-type TFTs showed fairly comparable performance. A functional CMOS inverter was fabricated using this novel scheme, indicating the potential use of our approach for various practical applications.

  8. Device physics of thin-film polycrystalline cells and modules. Annual subcontract report, December 6, 1993--December 5, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Sites, J.R.

    1995-05-01

    Progress has been made in several applications of device physics to thin-film polycrystalline cells and modules. At the cell level, results include a more quantitative separation of photon losses, the impact of second barriers on cell operation, and preliminary studies of how current-voltage curves are affected by band offsets. Module analysis includes the effects of the typical monolithic, series-connected cell geometry, analytical techniques when only the two module leads are accessible, and the impact of chopping frequency, local defects, and high-intensity beams on laser-scanning measurements.

  9. Electrodeposition of Water-Repellent Organic Dielectric Film as an Anti-Sticking Coating on Microelectromechanical System Devices

    Science.gov (United States)

    Sakata, Tomomi; Kuwabara, Kei; Shimamura, Toshishige; Sato, Norio; Nagase, Masao; Shimoyama, Nobuhiro; Kudou, Kazuhisa; Machida, Katsuyuki; Ishii, Hiromu

    2007-09-01

    In this paper, we propose a technique of preventing both wet-release-related and in-use sticking of actuators in microelectromechanical system (MEMS) devices. The technique involves the electrodeposition of a water-repellent organic dielectric film that renders the microstructure surface inactive towards the water used for rinsing. The source material is a core/shell emulsion, which consists of sulfonium cations with epoxy groups containing water-repellent silicone polymers. Applying this technique to the encapsulation of a microstructure confirms its effectiveness in preventing both release-related sticking and in-use sticking of a MEMS structure.

  10. Nano-Floating Gate Memory Devices Composed of ZnO Thin-Film Transistors on Flexible Plastics

    Directory of Open Access Journals (Sweden)

    Park Byoungjun

    2011-01-01

    Full Text Available Abstract Nano-floating gate memory devices were fabricated on a flexible plastic substrate by a low-temperature fabrication process. The memory characteristics of ZnO-based thin-film transistors with Al nanoparticles embedded in the gate oxides were investigated in this study. Their electron mobility was found to be 0.18 cm2/V·s and their on/off ratio was in the range of 104–105. The threshold voltages of the programmed and erased states were negligibly changed up to 103 cycles. The flexibility, memory properties, and low-temperature fabrication of the nano-floating gate memory devices described herein suggest that they have potential applications for future flexible integrated electronics.

  11. Device Process and Circuit Application Interaction for Harsh Electronics: Hf-In-Zn-O Thin Film Transistors as an Example

    KAUST Repository

    Ho, Chih-Hsiang

    2017-06-27

    The effects of Hf content on the radiation hardness of Hf-In-Zn-O thin-film transistors (HIZO TFTs) and HIZO TFTbased circuits are systemically examined. The evaluated circuits, including current-starved ring oscillator, energy harvesting and RF circuits are essential for space electronic systems. It is shown that HIZO TFTs with low Hf concentration have better initial performance while TFTs with high Hf concentration are more stable against radiation. On the other hand, for circuit application, the stable HIZO TFTs are not necessarily preferred for all circuits. The work demonstrates that understanding the device-circuit interactions is necessary for device optimization and circuit reliability improvements for harsh electronic systems.

  12. Atmospheric pressure chemical vapor deposition of CdTe for high efficiency thin film PV devices: Annual subcontract report, 26 January 1999--25 January 2000

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, P. V.; Kee, R.; Wolden, C.; Kestner, J.; Raja, L.; Kaydanov, V.; Ohno, T.; Collins, R.; Fahrenbruch, A.

    2000-05-30

    ITN's three year project Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High Efficiency Thin Film PV Devices has the overall objectives of improving thin film CdTe PV manufacturing technology and increasing CdTe PV device power conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16% efficient CdTe PV films, i.e., close spaced sublimation, but employs forced convection rather than diffusion as a mechanism of mass transport. Tasks of the APCVD program center on demonstration of APCVD of CdTe films, discovery of fundamental mass transport parameters, application of established engineering principles to the deposition of CdTe films, and verification of reactor design principles which could be used to design high throughput, high yield manufacturing equipment. Additional tasks relate to improved device measurement and characterization procedures that can lead to a more fundamental understanding of CdTe PV device operation and ultimately to higher device conversion efficiency and greater stability. Under the APCVD program, device analysis goes beyond conventional one-dimensional device characterization and analysis toward two dimension measurements and modeling. Accomplishments of the second year of the APCVD subcontract include: deposition of the first APCVD CdTe; identification of deficiencies in the first generation APCVD reactor; design, fabrication and testing of a ``simplified'' APCVD reactor; deposition of the first dense, adherent APCVD CdTe films; fabrication of the first APCVD CdTe PV device; modeling effects of CdSTe and SnOx layers; and electrical modeling of grain boundaries.

  13. Photochemical approach to high-barrier films for the encapsulation of flexible laminary electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Prager, L., E-mail: lutz.prager@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Helmstedt, U. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Herrnberger, H. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Kahle, O. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany); Kita, F. [AZ Electronic Materials Germany GmbH, Rheingaustraße 190-196, 65203 Wiesbaden (Germany); Münch, M. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Pender, A.; Prager, A.; Gerlach, J.W. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Stasiak, M. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany)

    2014-11-03

    Based on results of preceding research and development, thin gas barriers were made by wet application of perhydropolysilazane solution onto polymer films and its subsequent photo-initiated conversion to dense silica layers applying vacuum ultraviolet irradiation. Compared to the state of the art, these layers were sufficiently improved and characterized by spectroscopic methods, by scanning electron microscopy and by gas permeation measurements. Water vapor transmission rates (WVTR) below 10{sup −2} g m{sup −2} d{sup −1} were achieved. In this way, single barrier films were developed and produced on a pilot plant from roll to roll, 250 mm wide, at speeds up to 10 m min{sup −1}. Two films were laminated using adhesives curable with ultraviolet (UV) light and evaluated by peel tests, gas permeation measurement and climate testing. It could be shown that the described high-barrier laminates which exhibit WVTR ≈ 5 × 10{sup −4} g m{sup −2} d{sup −1}, determined by the calcium mirror method, are suitable for encapsulation of flexible thin-film photovoltaic modules. Durability of the encapsulated modules could be verified in several climate tests including damp-heat, thermo-cycle (heating, freezing, wetting) and UV exposures which are equivalent to more than 20 years of endurance at outdoor conditions in temperate climate. In the frame of further research and technical development it seems to be possible to design a cost efficient industrial scale process for the production of encapsulation films for photovoltaic applications. - Highlights: • Dense silica barrier layers were developed by a photochemical approach. • Polymer based barrier films were laminated yielding flexible high-barrier films. • Using these laminates photovoltaic test modules were encapsulated and tested. • A durability of more than 20 years at outdoor conditions could be proved.

  14. Growth and analysis of highly oriented (11n) BCSCO films for device research

    Energy Technology Data Exchange (ETDEWEB)

    Raina, K.K.; Pandey, R.K. [Texas A& M Univ., College Station, TX (United States)

    1994-12-31

    Films of BCSCO superconductor of the type Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub x} have been grown by liquid phase epitaxy method (LPE), using a partially closed growth chamber. The films were grown on (001) and (110) NdGaO{sub 3} substrates by slow cooling process in an optimized temperature range below the peritectic melting point (880{degrees}C) of Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub 8}. Optimization of parameters, such as seed rotation, soak of initial growth temperature and growth period results in the formation of 2122 phase BCSCO films. The films grown at rotation rates of less than 30 and more than 70 rpm are observed to be associated with the second phase of Sr-Ca-Cu-O system. Higher growth temperatures (>860{degrees}C) also encourage to the formation of this phase. XRD measurements show that the films grown on (110) NdGaO{sub 3} have a preferred (11n)-orientation. It is pertinent to mention here that in our earlier results published elsewhere we obtained c-axis oriented Bi{sub 2}CaSr{sub 2}Cu{sub 2}O{sub 8} phase films on (001) NdGaO{sub 3} substrate. Critical current density is found to be higher for the films grown on (110) than (001) NdGaO{sub 3} substrate orientation. The best values of zero resistance (T{sub co}) and critical current density obtained are 87 K and 10{sup 5} A/cm{sup 2}, respectively.

  15. Exploring relationship between face-to-face interaction and team performance using wearable sensor badges.

    Science.gov (United States)

    Watanabe, Jun-ichiro; Ishibashi, Nozomu; Yano, Kazuo

    2014-01-01

    Quantitative analyses of human-generated data collected in various fields have uncovered many patterns of complex human behaviors. However, thus far the quantitative evaluation of the relationship between the physical behaviors of employees and their performance has been inadequate. Here, we present findings demonstrating the significant relationship between the physical behaviors of employees and their performance via experiments we conducted in inbound call centers while the employees wore sensor badges. There were two main findings. First, we found that face-to-face interaction among telecommunicators and the frequency of their bodily movements caused by the face-to-face interaction had a significant correlation with the entire call center performance, which we measured as "Calls per Hour." Second, our trial to activate face-to-face interaction on the basis of data collected by the wearable sensor badges the employees wore significantly increased their performance. These results demonstrate quantitatively that human-human interaction in the physical world plays an important role in team performance.

  16. Exploring Relationship between Face-to-Face Interaction and Team Performance Using Wearable Sensor Badges

    Science.gov (United States)

    Watanabe, Jun-ichiro; Ishibashi, Nozomu; Yano, Kazuo

    2014-01-01

    Quantitative analyses of human-generated data collected in various fields have uncovered many patterns of complex human behaviors. However, thus far the quantitative evaluation of the relationship between the physical behaviors of employees and their performance has been inadequate. Here, we present findings demonstrating the significant relationship between the physical behaviors of employees and their performance via experiments we conducted in inbound call centers while the employees wore sensor badges. There were two main findings. First, we found that face-to-face interaction among telecommunicators and the frequency of their bodily movements caused by the face-to-face interaction had a significant correlation with the entire call center performance, which we measured as “Calls per Hour.” Second, our trial to activate face-to-face interaction on the basis of data collected by the wearable sensor badges the employees wore significantly increased their performance. These results demonstrate quantitatively that human-human interaction in the physical world plays an important role in team performance. PMID:25501748

  17. Exploring relationship between face-to-face interaction and team performance using wearable sensor badges.

    Directory of Open Access Journals (Sweden)

    Jun-ichiro Watanabe

    Full Text Available Quantitative analyses of human-generated data collected in various fields have uncovered many patterns of complex human behaviors. However, thus far the quantitative evaluation of the relationship between the physical behaviors of employees and their performance has been inadequate. Here, we present findings demonstrating the significant relationship between the physical behaviors of employees and their performance via experiments we conducted in inbound call centers while the employees wore sensor badges. There were two main findings. First, we found that face-to-face interaction among telecommunicators and the frequency of their bodily movements caused by the face-to-face interaction had a significant correlation with the entire call center performance, which we measured as "Calls per Hour." Second, our trial to activate face-to-face interaction on the basis of data collected by the wearable sensor badges the employees wore significantly increased their performance. These results demonstrate quantitatively that human-human interaction in the physical world plays an important role in team performance.

  18. High work function of Al-doped zinc-oxide thin films as transparent conductive anodes in organic light-emitting devices

    Science.gov (United States)

    Kim, T. W.; Choo, D. C.; No, Y. S.; Choi, W. K.; Choi, E. H.

    2006-12-01

    Deposition of Al-doped ZnO (AZO) films with various film thicknesses on glass substrates was performed to investigate the feasibility of using AZO films as anode electrodes in organic light-emitting devices (OLEDs). The electrical resistivity of the AZO films with a 180-nm thickness was 4.085 × 10 -2 Ω cm, and the average optical transmittance in the visible range was 80.2%. The surface work function for the AZO films, determined from the secondary electron emission coefficients obtained with a focused ion beam, was as high as 4.62 eV. These results indicate that AZO films grown on glass substrates hold promise for potential applications as anode electrodes in high-efficiency OLEDs.

  19. Development of a Mechatronic Syringe Pump to Control Fluid Flow in a Microfluidic Device Based on Polyimide Film

    Science.gov (United States)

    Sek Tee, Kian; Sharil Saripan, Muhammad; Yap, Hiung Yin; Fhong Soon, Chin

    2017-08-01

    With the advancement in microfluidic technology, fluid flow control for syringe pump is always essential. In this paper, a mechatronic syringe pump will be developed and customized to control the fluid flow in a poly-dimethylsiloxane (PDMS) microfluidic device based on a polyimide laminating film. The syringe pump is designed to drive fluid with flow rates of 100 and 1000 μl/min which intended to drive continuous fluid in a polyimide based microfluidic device. The electronic system consists of an Arduino microcontroller board and a uni-polar stepper motor. In the system, the uni-polar stepper motor was coupled to a linear slider attached to the plunger of a syringe pump. As the motor rotates, the plunger pumps the liquid out of the syringe. The accuracy of the fluid flow rate was determined by adjusting the number of micro-step/revolution to drive the stepper motor to infuse fluid into the microfluidic device. With the precise control of the electronic system, the syringe pump could accurately inject fluid volume at 100 and 1000 μl/min into a microfluidic device.

  20. Atmospheric pressure plasma jet-synthesized electrochromic organomolybdenum oxide thin films for flexible electrochromic devices

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yung-Sen, E-mail: yslin@fcu.edu.tw; Tsai, Tsung-Hsien; Tien, Shih-Wei

    2013-02-01

    An investigation is conducted into fast synthesis of electrochromic organomolybdenum oxide (MoO{sub x}C{sub y}) thin films onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates via atmospheric pressure plasma jet. A precursor [molybdenum carbonyl, Mo(CO){sub 6}] vapor, carried by argon gas, is injected into air plasma torch to synthesize MoO{sub x}C{sub y} films for offering extraordinary electrochromic performance. Only low driving voltages from − 1 V to 1 V are needed to offer reversible Li{sup +} ion intercalation and deintercalation in a 1 M LiClO{sub 4}-propylene carbonate electrolyte. Light modulation with transmittance variation of up to 61%, optical density change of 0.54 and coloration efficiency of 37.5 cm{sup 2}/C at a wavelength of 550 nm after 200 cycles of cyclic voltammetry switching measurements is achieved. - Highlights: ► Fast deposition of MoO{sub x}C{sub y} film by an atmospheric pressure plasma jet ► Organic–inorganic hybrid MoO{sub x}C{sub y} films synthesized ► Flexible and electrochromic MoO{sub x}C{sub y} films produced.

  1. Superconducting YBa2Cu3O7 films for novel (opto)electronic device structures

    Science.gov (United States)

    Pavuna, D.; Dwir, B.; Gauzzi, A.; James, J. H.; Kellett, B. J.

    1991-02-01

    This short overview briefly summarizes the most important parameters for successful preparation and associated properties of thin films of YBa2Cu3O(7-delta) (YBCO) superconductors. The principles are illustrated by using the example of monotarget ion beam sputtering technique: YBCO films grown in situ on SrTiO3 show Tc(onset) = 92 K and Tco = 91 K. Magnetron sputtering, E-beam evaporation, laser ablation and molecular beam epitaxy are discussed. In situ ion beam sputtering of YBCO on Si and GaAs substrates with intermediate, conducting Indium Tin Oxide (ITO) buffer layers is also presented. Uniform, textured YBCO films on ITO exhibit Tc(onset) at 92 K and Tco at 68 K and 60 K on Si and GaAs substrates, respectively; the latter is the highest Tc reported on GaAs. YBCO/ITO films exhibit metallic resistivity behavior. Finally, the performance of a simple optical bolometer demonstrated on YBCO films and the results of tunneling measurements on the window-type YBCO-Pb tunnel junctions are discussed.

  2. Fabrication and Characterization of Brush-Printed p-Type Bi0.5Sb1.5Te3 Thick Films for Thermoelectric Cooling Devices

    Science.gov (United States)

    Wu, Han; Liu, Xing; Wei, Ping; Zhou, Hong-Yu; Mu, Xin; He, Dan-Qi; Zhu, Wan-Ting; Nie, Xiao-Lei; Zhao, Wen-Yu; Zhang, Qing-Jie

    2016-11-01

    Bismuth telluride alloys are promising thermoelectric materials used for portable and wearable cooling devices due to their excellent thermoelectric properties near the ambient temperature. Here, a simple and cost-effective brush-printing technique, together with a subsequent annealing treatment, has been used to prepare Bi2Te3-based thick films and prototype devices. The composition, microstructure, and electrical properties of the brush-printed p-type Bi0.5Sb1.5Te3 thick films at different annealing temperatures are investigated. It is found that annealing temperature plays an important role in promoting densification and preventing the film from cracking, hence improving the electrical transport properties. The maximum power factor of the brush-printed thick films is 0.15 mW K-2 m-1 when annealed at 673 K for 4 h. A prototype thermoelectric device is manufactured by connecting the brush-printed p-type Bi0.5Sb1.5Te3 and n-type Bi2Te2.7Se0.3 thick films with Cu thick-film electrodes on an Al2O3 substrate. The cooling performance of the thermoelectric device is evaluated by measuring the temperature difference produced under applied currents.

  3. A new PC based semi-automatic TLD badge reader system for personnel monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, M.S.; Pradeep, Ratna; Kannan, S. [Radiation Protection and Instrumentation Section, Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai (India)

    2000-05-01

    A semi-automatic TDL (thermo-luminescence dosimeter) badge reader system has been developed for large-scale personnel monitoring of the radiation workers. The BARC (Bhabha Atomic Research Centre) TLD badge consists of three dosimeters of CaSO{sub 4}: Dy embedded in Teflon, each of 0.8mm/0.4mm thickness and 13mm diameter. 50 such TLD badges loaded in a magazine are automatically processed one by one using a motor driven mechanical assembly. Except for the entry of identification numbers in the same sequence in which the badges are loaded in the magazine, the entire process is automatic. All the front-end functions in the reader assembly are controlled by an Atmel 89C51 microcontroller on command from a Personal Computer through an RS-232 serial interface. A hot gas (N{sub 2}) heating system with electronic temperature control is used for rapid and uniform heating of the dosimeters. The glow curve and temperature profile of TL dosimeter is displayed on-line on a PC monitor and stored in the memory along with the badge data at the end of each reading cycle. The other features of the reader system are reproducible time temperature profile of hot gas, software based dark current sampling and subtraction, auto ranging, built-in safeguards in both hardware and software against mechanical and electronic failures, etc. To enable a wide range of measurement with high sensitivity to lower levels of TL, the EHT is automatically switched to a lower value when high TL output is encountered. The software is developed in to two parts. The first one consists of a ROM based assembly language software for the 89C51 microcontroller, which monitors various, circuits in the reader assembly and controls the motorized movements. The second part is a password protected user friendly, menu driven software package written in 'C' language for the reader control, on-line glow curve display and storage, dose data management record keeping and printout of dose reports, etc. Elaborate

  4. Method for manufacturing electrical contacts for a thin-film semiconductor device

    Science.gov (United States)

    Carlson, David E.; Dickson, Charles R.; D'Aiello, Robert V.

    1988-11-08

    A method of fabricating spaced-apart back contacts on a thin film of semiconductor material by forming strips of buffer material on top of the semiconductor material in locations corresponding to the desired dividing lines between back contacts, forming a film of metal substantially covering the semiconductor material and buffer strips, and scribing portions of the metal film overlying the buffer strips with a laser without contacting the underlying semiconductor material to separate the metal layer into a plurality of back contacts. The buffer material serves to protect the underlying semiconductor material from being damaged during the laser scribing. Back contacts and multi-cell photovoltaic modules incorporating such back contacts also are disclosed.

  5. A novel absorptive thin film for laser welding in optoelectronic device capsulation

    Institute of Scientific and Technical Information of China (English)

    JIANG Shao-ji; JIN Tao; LI Wei-duo; WANG He-zhou

    2005-01-01

    A kind of absorptive thin film was designed and used in laser welding of SiO2, Si and LiNbO3. This absorptive thin film of three-layer metal-dielectric-metal structure is designed for further reducing the high reflectance of the Nd:YAG laser beam on the surface of the tin layer that is utilized as solder between the transparent parent materials. The actual absorption of laser energy in experiment exceeds 99%. This combination of absorber and solder transformed the laser energy into heat efficiently and decreased the minimum necessary incident laser power transmitting through the transparent parent materials. As a result, the damage of the parent materials, which is suffered from laser transmission, was avoided; On the other hand, mechanical stability of the welded materials had been improved. Experiment had been made to show the difference between welding with and without the absorptive thin film.

  6. Electrochromic Metallo-Organic Nanoscale Films: Fabrication, Color Range, and Devices.

    Science.gov (United States)

    Elool Dov, Neta; Shankar, Sreejith; Cohen, Dana; Bendikov, Tatyana; Rechav, Katya; Shimon, Linda J W; Lahav, Michal; van der Boom, Milko E

    2017-08-23

    In this study, we demonstrate a versatile approach for the formation of electrochromic nanoscale assemblies on transparent conductive oxides on both rigid and flexible substrates. Our method is based on the application of alternating spin-coated layers of well-defined metal polypyridyl complexes and a palladium(II) salt to form electrochemically addressable films with a high chromophore density. By varying the central metal ion of the polypyridyl complexes (Os, Ru, and Fe) and their ligands and by mixing these complexes, coatings with a wide range of colors can be achieved. These coatings cover a large area of RGB color space. The coloration intensities of these nanoscale films can be tuned by the number of deposition steps. The materials have very attractive ON/OFF ratios, electrochemical stabilities, and coloration efficiencies. Reversible color-to-colorless and color-to-color transitions were demonstrated, and the films were further integrated into sandwich cells.

  7. Devices Would Detect Drugs In Sweat

    Science.gov (United States)

    Mintz, Fredrick W.; Richards, Gil; Kidwell, David A.; Foster, Conrad; Kern, Roger G.; Nelson, Gregory A.

    1996-01-01

    Proposed devices worn on skin detect such substances as methamphetamine, morphine, tetrahydrocannabinol (THC), and cocaine in wearers' sweat and transmits radio signals in response to computer queries. Called Remote Biochemical Assay Telemetering System (R-BATS), commonly referred to as "drug badge," attached to wearer by use of adhesive wristband. Used for noninvasive monitoring of levels of prescribed medications in hospital and home-care settings and to detect overdoses quickly.

  8. Device level optimization of poly(vinylidene fluoride-trifluoroethylene)–zinc oxide polymer nanocomposite thin films for ferroelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    C K, Subash, E-mail: cksubash08@gmail.com; Valiyaneerilakkal, Uvais; Varghese, Soney [Nanomaterials and Device Research Laboratory, School of Nano Science and Technology, National Institute of Technology Calicut, Calicut, Kerala 673601 (India); Singh, Kulwant [Nanomaterials and Device Research Laboratory, School of Nano Science and Technology, National Institute of Technology Calicut, Calicut, Kerala 673601 (India); Department of ECE, B.K. Birla Institute of Engineering and Technology, Pilani, Rajasthan 333031 (India)

    2015-11-28

    Polymer nanocomposite was prepared using poly(vinylidene fluoride-trifluoroethylene) and zinc oxide (ZnO) nanopowder, which are ferroelectric in nature. Nanocomposite was prepared in various concentrations(0.2, 0.4, 0.8, and 1 wt. %) using probe ultra-sonication, followed by spin coating and annealing at 120 °C for 2 h to improve the formation of β-phase. Metal-ferroelectric-metal capacitor was fabricated using this optimized thin film as a ferroelectric layer. Device level optimization was carried out by polarization-electric field (P-E) hysteresis studies of this film, which shows polarization enhancement of composite. Various characterization techniques like atomic force microscopy, Fourier transform infra-red spectroscopy (FT-IR), Differential scanning calorimetry, and X-ray diffraction were used to study the β-phase formation of nancomposite. The capacitance–voltage (C-V) and current-voltage (I-V) characteristics were studied through varying frequency and temperature. C-V measurements show an increase of 79% in the capacitance of polymer nanocomposite, which can be used for the fabrication of ferroelectric devices.

  9. Microstructure and electroluminescent performance of chemical vapor deposited zinc sulfide doped with manganese films for integration in thin film electroluminescent devices

    Science.gov (United States)

    Topol, Anna Wanda

    Zinc sulfide (ZnS) doped with manganese (Mn), ZnS:Mn, is widely recognized as the brightest and most effective electroluminescent (EL) phosphor used in current thin film electroluminescent (TFEL) devices. ZnS acts as a host lattice for the luminescent activator, Mn, leading to a highly efficient yellow-orange EL emission, and resulting in a wide array of applications in monochrome, multi-color and full color displays. Although this wide band dap (3.7 eV) material can be prepared by several deposition techniques, the chemical vapor deposition (CVD) is the most promising for TFEL applications in terms of viable deposition rates, high thickness and composition uniformity, and excellent yield over large area panels. This study describes the development and optimization of a CVD ZnS:Mn process using diethylzinc [(C2H5)2Zn, DEZ], di-pi-cyclopentadienylmanganese [(C5H5)2Mn, CPMn], and hydrogen sulfide [H2S] as the chemical sources for, respectively, Zn, Mn, and S. The effects of key deposition parameters on resulting Film microstructure and performance are discussed, primarily in the context of identifying an optimized process window for best electroluminescence behavior. In particular, substrate temperature was observed to play a key role in the formation of high quality crystalline ZnS:Mn films leading to improved brightness and EL efficiency. Further investigations of the influence of temperature treatment on the structural characteristics and EL performance of the CVD ZnS:Mn film were carried out. In this study, the influence of post-deposition annealing both in-situ and ex-situ annealing processes, on chemical, structural, and electroluminescent characteristics of the phosphor layer are described. The material properties of the employed dielectric are among the key factors determining the performance, stability and reliability of the TFEL display and therefore, the choice of dielectric material for use in ACTFEL displays is crucial. In addition, the luminous

  10. Use of the asymmetric planar hall resistance of an Fe film for possible multi-value memory device applications.

    Science.gov (United States)

    Yoo, Taehee; Khym, S; Lee, Hakjoon; Lee, Sangyeop; Kim, Shinhee; Shin, Jinsik; Lee, Sanghoon; Liu, X; Furdyna, J K

    2011-07-01

    Systematic planar Hall measurements have been performed on a ferromagnetic Fe film grown on a standard (001) GaAs substrate at room temperature. The angular dependence of the planar Hall effect revealed the presence of both four-fold (cubic) and two-fold (uniaxial) anisotropies in the 7 nm thick Fe film. The dominance of the four-fold symmetric anisotropy, however, provided four magnetic easy axes near the (100) direction, which results in a two step switching phenomenon in the magnetization reversal process. An interesting asymmetric hysteresis loop was observed in the planar Hall resistance (PHR) when the turning point of the field scan is set at the value in the region of the second transition. The intermediate resistance states appearing in the asymmetric PHR loop were understood in terms of mutli-domain structures formed during the second switching of magnetization. Such multi-domain structure of the Fe film showing robust time stability provided additional Hall resistance states, which can be used for multi-valued memory device applications.

  11. In-situ deposition and processing of YBa2Cu3O(7-x) films and multilayers for optoelectronic devices

    Science.gov (United States)

    Villegier, J. C.; Moriceau, H.; Boucher, H.; di Cioccio, L.; Chicault, R.

    1991-03-01

    In situ direct deposition at about 700 C of thin YBa2Cu3O(7-x) superconductive films and multilayers has been done by three techniques using stoichiometric YBa2Cu3O(7-x) sintered targets. Excimer laser ablation in a dc magnetron system with hollow and planar targets leads to 0.5-, 1.2-, and 2.5-in diameter uniformly superconductive layers under static conditions. High critical current densities associated with low resistivity and good epitaxial behavior are achieved on top of MgO, SrTiO3, LaAlO3, and YSZ single-crystal wafers. High-quality c-oriented films are routinely obtained by means of a dc magnetron on large sapphire substrates covered by a YSZ RF sputtered buffer layer. The infrared properties of such films have been checked at 1.15-micron wavelength. In order to achieve active devices, small YBa2Cu3O7-YSZ-Ag tunnel junctions and arrays have been successfully patterned in the superconductor/insulator/normal-metal trilayers using SNOP (selective niobium overlap process).

  12. Effects of self-assembled gold nanoparticles on YBa2Cu3O7-δ thin films and devices

    Science.gov (United States)

    Michalowski, P.; Katzer, C.; Schmidl, F.; Seidel, P.

    2012-11-01

    In our work we prepared YBa2Cu3O7-δ (YBCO) thin films with self-assembled gold nanoparticles on SrTiO3 (STO) substrates. We carried out different experiments to determine the effects on the crystallographic properties of the YBCO matrix as well as of the gold nanoparticles. Furthermore, we investigated how the particles influence the superconducting parameters of the film, e.g. the critical temperature TC and the critical current density jC. To ascertain jC we employed magneto-optical Faraday microscopy. In addition, the YBCO film was deposited and structured on STO bi-crystal substrates, thus producing grain boundary Josephson junctions. We studied those junctions with respect to the normal state resistance RN, and the dependence of the critical current IC on the temperature T as well as on the magnetic flux Φ. Finally, we prepared direct current superconducting quantum interference device (dc-SQUID) gradiometers and embedded gold nanoparticles at well-defined areas such as only the antenna or the SQUID region. We measured the flux noise in a shielded environment using an ac-bias reversal technique and compared it with that of sensors without gold nanoparticles. Thus, we demonstrate a new preparation method and an innovative application of gold nanoparticles.

  13. Electro-optical evaluation of tungsten oxide and vanadium pentoxide thin films for modeling an electrochromic device

    Directory of Open Access Journals (Sweden)

    H Najafi Ashtiani

    2015-01-01

    Full Text Available In this study, tungsten oxide and vanadium oxide electrochromic thin films were placed in vacuum and in a thickness of 200 nm on a transparent conductive substrate of SnO2:F using the physical method of thermal evaporation. Then they were studied for the optical characteristics in the wavelength range from 400 to 700 nm and for their electrical potentials in the range form +1.5 to -1.5 volts. The films were post heated in order to assess changes in energy gap with temperature, at temperatures120 , 300 and 500°C. Refractive and extinction coefficients and the transition type of films in the visible light range and in the thickness of 200 nm were determined and measured. X-ray diffraction pattern and SEM images and cyclic Voltammetry of layers were also studied. The results of this study due to the deposition of layers, the layer thickness selected, the type of substrate, the range of annealing temperatures and selected electrolyte were in full compliance with the works of other researchers [1,2,3]. Therefore, these layers with features such as crystal structure, refractive and even extinction coefficients in the range of visible light, the appropriate response of chromic switch in the replication potential, good adhesion to the substrate, and the high amount of optical transmition and so on, prove useful to be used in an electrochromic device

  14. Cu2ZnSnS4 thin films solar cells: material and device characterization

    OpenAIRE

    2014-01-01

    Cu2ZnSnS4 (CZTS) quaternary compound has attracted much attention in the last years as new abundant, low cost and non-toxic material, with desirable properties for thin film photovoltaic (PV) applications. In this work, CZTS thin films were grown using two different processes, based on vacuum deposition of precursors, followed by a heat treatment in sulphur atmosphere. The precursors were deposited using two different approaches: (i) electron-beam evaporation of multiple stacks made of ZnS, S...

  15. Characteristics of Electro-Optic Device Using Conducting Polymers, Polythiophene and Polypyrrole Films

    Science.gov (United States)

    Kaneto, Keiichi; Yoshino, Katsumi; Inuishi, Yoshio

    1983-07-01

    Detailed characteristics of electro-optic elements (color switching and memory) utilizing the spectral change of conducting polymers by electrochemical doping and undoping are studied. The response time of color switching, for example, red≤ftrightarrowblue in polythiophene film in the electrolyte of LiBF4/acetonitrile is 30˜100 msec under the applied voltages of -2.0{≤ftrightarrow}+4.0 V vs. Li plate. More than 103 cycles of color switch are observed quite reproducibly. Three color states of yellow green, dark brown and blue are demonstrated for polypyrrole film.

  16. Contribution of the cashew gum (Anacardium occidentale L.) for development of layer-by-layer films with potential application in nanobiomedical devices

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, I.M.S. [Departamento de Quimica, Centro de Ciencias da Natureza, CCN, Universidade Federal do Piaui, UFPI, Teresina, PI, 64049-550 (Brazil); Nucleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, Campus Parnaiba, CMRV, Universidade Federal do Piaui, UFPI, Parnaiba, PI, 64202-020 (Brazil); Zampa, M.F. [Nucleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, Campus Parnaiba, CMRV, Universidade Federal do Piaui, UFPI, Parnaiba, PI, 64202-020 (Brazil); Campus Parnaiba, Instituto Federal de Educacao Ciencia e Tecnologia do Piaui, IFPI, Parnaiba, PI, 64210-260 (Brazil); Moura, J.B.; Santos, J.R. dos [Departamento de Quimica, Centro de Ciencias da Natureza, CCN, Universidade Federal do Piaui, UFPI, Teresina, PI, 64049-550 (Brazil); Eaton, P. [REQUIMTE, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, Porto, 4169-007 (Portugal); Zucolotto, V. [Grupo de Biofisica Molecular Sergio Mascarenhas, Instituto de Fisica de Sao Carlos, IFSC, USP, Sao Carlos, SP, 13566-590 (Brazil); and others

    2012-08-01

    The search for bioactive molecules to be employed as recognition elements in biosensors has stimulated researchers to pore over the rich Brazilian biodiversity. In this sense, we introduce the use of natural cashew gum (Anacardium occidentale L.) as an active biomaterial to be used in the form of layer-by-layer films, in conjunction with phthalocyanines, which were tested as electrochemical sensors for dopamine detection. We investigated the effects of chemical composition of cashew gum from two different regions of Brazil (Piaui and Ceara states) on the physico-chemical characteristics of these nanostructures. The morphology of the nanostructures containing cashew gum was studied by atomic force microscopy which indicates that smooth films punctuated by globular features were formed that showed low roughness values. The results indicate that, independent of the origin, cashew gum stands out as an excellent film forming material with potential application in nanobiomedical devices as electrochemical sensors. Highlights: Black-Right-Pointing-Pointer This study focused on the use of cashew gum for the formation of LbL films. Black-Right-Pointing-Pointer LbL films containing cashew gums were investigated by AFM and cyclic voltammetry. Black-Right-Pointing-Pointer Cashew gum contributed to obtain stable films with well-defined redox processes. Black-Right-Pointing-Pointer Cashew gum films detected dopamine in low concentrations. Black-Right-Pointing-Pointer These LbL films presented potential application in nanobiomedical devices.

  17. "In our play we reveal what kind of people we are" - Identity building through gamification and digital badges

    Directory of Open Access Journals (Sweden)

    Jakub Stogr

    2014-08-01

    Full Text Available The lifetime of skills and particular knowledge is getting shorter and the new skills for new future positions are being currently obtained as part of lifelong learning process. Even if a part of these processes is actually recognized and fixed in a form of degrees, certificates and references, some of these achievements could become obsolete, some of them not useful in current practice and sometimes even weird. Nevertheless, these (learning goals were reached; the learning process as such could be a fruitful life-lesson and the key factor for the future success. The huge potential of Mozilla Open Badge Infrastructure (MOBI – and in general any system that provides digital badges as a kind of incentive or reward – is therefore in collaborative setting that allows comparison with other “players” and mapping the progress "against the others". Without the possibility of comparison, building of e-portfolio becomes much more about storytelling, creating diary or blog and adding a context to selected achievements. Any knowledge provider issuing badges should therefore be able to provide additional information about the complexity of learning environment (incl. statistics, not only short description of criteria as requested in MOBI. This paper further describes opportunities and possible practical usage of gamification and digital badges for stimulation of (lifelong learning.

  18. Design of a personnel dosimetry badge system for a new TL material CaSO-4:Dy,P

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. K.; Kwon, J. W.; Lee, J. K. [Hanyang, Univ., Seoul (Korea, Republic of); Kim, J. L. [KAERI, Daejon (Korea, Republic of)

    2002-07-01

    A badge system for a new type of CaSO{sub 4}:Dy based TL dosimeter, KCT-300 developed in KAERI, has been designed by analyzing response data obtained from both experiments and Monte Carlo simulations. The badge, named KCT-300PB, consists of three characterized areas: the open window area, the energy compensation area, and the energy information area. Different filter combinations in each area allowed to compensate energy dependency of the responses and to provide both the deep dose equivalent Hp(10) and the shallow dose equivalent Hp(0.07) with acceptable accuracy. The relative response under energy compensation area is in the range of 0.75 1.0 over the photon energy range from 20 keV to 662 keV. This means badge system KCT-300PB satisfies ANSI and ISO standards prescribed for type-testing of personnel dosimeters. By introducing hole tapered at 60 o angle to the filter, angular dependence of the response to low energy photon was considerably improved. The KCT-300PB is capable to discern beta-gamma mixed fields by utilizing the responses of the open window area and the energy compensation area and capable to resolve X-rays or X- rays and gamma mixed fields by analyzing the ratio of difference in responses. It is a potential advantage of this badge system to make the dose evaluation algorithm simple.

  19. Effects of the Badge Mechanism on Self-Efficacy and Learning Performance in a Game-Based English Learning Environment

    Science.gov (United States)

    Yang, Jie Chi; Quadir, Benazir; Chen, Nian-Shing

    2016-01-01

    A growing number of studies have been conducted on digital game-based learning (DGBL). However, there has been a lack of attention paid to individuals' self-efficacy and learning performance in the implementation of DGBL. This study therefore investigated how the badge mechanism in DGBL enhanced users' self-efficacy in the subject domain of…

  20. An optical reflected device using a molecularly imprinted polymer film sensor

    Energy Technology Data Exchange (ETDEWEB)

    Wu Nan; Feng Liang; Tan Yiyong [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Hu Jiming, E-mail: jmhu@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

    2009-10-19

    A novel and highly selective optical sensor with molecularly imprinted polymer (MIP) film was fabricated and investigated. The optical sensor head employing a medium finesse molecularly imprinted polymer film has been fabricated and characterised. A blank polymer and formaldehyde imprinted polymer were using methacrylic acid as the functional monomer and the ethylene glycol dimethacrylate as a crosslinker. The transduction mechanism is discussed based on the changes of optical intensity of molecularly imprinted polymer film acting as an optical reflected sensor. Template molecules, which diffused into MIP, could cause film density, and refractive index change, and then induce measurable optical reflective intensity shifts. Based on the reflective intensity shifts, an optical reflection detection of formaldehyde was achieved by illuminating MIP with a laser beam. For the same MIP, the reflective intensity shift was proportional to the amount of template molecule. This optical sensor, based on an artificial recognition system, demonstrates long-time stability and resistance to harsh chemical environments. As the research moves forward gradually, we establish the possibilities of quantitative analysis primly, setting the groundwork to the synthesis of the molecular imprinted optical fiber sensor. The techniques show good reproducibility and sensitivity and will be of significant interest to the MIPcommunity.

  1. In situ preparation of YH2 thin films by PLD for switchable devices

    NARCIS (Netherlands)

    Dam, B; Lokhorst, AC; Remhof, A; Heijna, MCR; Rector, JH; Borsa, D; Kerssemakers, JWJ

    2003-01-01

    We prepared epitaxial YH2 films on (111) CaF2 by pulsed laser deposition (PLD) from a metallic yttrium target. Without adding any reactive hydrogen, the dihydride is formed in situ due to the hydrogen evolving from the metallic target which contains similar to7 at% H. Upon pulsed laser irradiation,

  2. Challenges in the Assembly and Handling of Thin Film Capped MEMS Devices

    NARCIS (Netherlands)

    Zaal, J.J.M.; Van Driel, W.D.; Zhang, G.Q.

    2010-01-01

    This paper discusses the assembly challenges considering the design and manufacturability of a Wafer Level Thin Film Package in MEMS applications. The assembly processes are discussed. The loads associated with these processes are illustrated and evaluated. Numerical calculations are combined with e

  3. MI004 miniaturised, high performance ferroelectric and piezoelectric thin film devices

    NARCIS (Netherlands)

    Klee, M.; Keur, W.; Mauczok, R.; van Esch, H.; de Wild, M.; Liu, J.; Roest, A.; Reimann, K.; Renders, Ch.; Peters, L.; Tiggelman, M.P.J.; Wunnicke, O.; Neumann, K.

    2008-01-01

    Thin film ferroelectric capacitors have been integrated with resistors and active functions such as ESD protection into small, miniaturized modules, which enable a board space saving of up to 80%. With the optimum materials and processes, integrated capacitors with capacitance densities of up to 100

  4. Matrix effect on leaching of Bisphenol A diglycidyl ether (BADGE) from epoxy resin based inner lacquer of aluminium tubes into semi-solid dosage forms.

    Science.gov (United States)

    Lipke, Uwe; Haverkamp, Jan Boris; Zapf, Thomas; Lipperheide, Cornelia

    2016-04-01

    To study the impact of different semi-solid dosage form components on the leaching of Bisphenol A (BPA) and Bisphenol A diglycidyl ether (BADGE) from the epoxy resin-based inner lacquer of aluminium tubes, the tubes were filled with different matrix preparations and stored at an elevated temperature. Despite compliance with the European Standards EN 15348 and EN 15766 on porosity and polymerisation of internal coatings of aluminium tubes, the commercially available tubes used in the study contained an increased amount of polymerisation residues, such as unbound BPA, BADGE and BADGE derivatives in the lacquer, as determined by acetonitrile extraction. Storage of Macrogol ointments in these tubes resulted in an almost quantitative migration of the unbound polymerisation residues from the coating into the ointment. In addition, due to alterations observed in the RP-HPLC chromatograms of the matrix spiked with BADGE and BADGE derivatives it is supposed that the leachates can react with formulation components. The contamination of the medicinal product by BPA, BADGE and BADGE derivatives can be precluded by using aluminium tubes with an internal lacquer with a low degree of unbound polymerisation residues. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  5. Junction formation in CuInSe{sub 2}-based thin-film devices

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, K.; Wiesner, H.; Asher, S.; Bhattacharya, R.N.; Keane, J.; Contreras, M.A.; Noufi, R. [National Center for Photovoltaics, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

    1999-03-01

    The nature of the interface between CuInSe{sub 2} (CIS) and the chemical bath deposited CdS layer has been investigated. We show that heat-treating the absorbers in Cd- or Zn-containing solutions in the presence of ammonium hydroxide sets up a chemical reaction which facilitates an extraction of Cu from the lattice and an in-diffusion of Cd. The characteristics of devices made in this manner suggest that the reaction generates a thin, n-doped region in the absorber. It is quite possible that the CdS/CuInSe{sub 2} device is a buried, shallow junction with a CdS window layer, rather than a heterojunction. We have used these ideas to develop methods for fabricating devices without CdS or Cd. A 14.2{percent} efficiency ZnO/CIGS device was obtained through aqueous treatment in Zn solutions. {copyright} {ital 1999 American Institute of Physics.}

  6. Junction Formation in CuInSe{sub 2} Based Thin Film Devices

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, K.; Wiesner, H.; Asher, S.; Bhattacharya, R. N.; Keane, J.; Contreras, M.; Noufi, R.

    1998-11-18

    The nature of the interface between CuInSe{sub 2} (CIS) and the chemical bath deposited CdS layer has been investigated. We show that heat-treating the absorbers in Cd- or Zn-containing solutions in the presence of ammonium hydroxide sets up a chemical reaction which facilitates an extraction of Cu from the lattice and an in-diffusion of Cd. The characteristics of devices made in this manner suggest that the reaction generates a thin, n-doped region in the absorber. It is quite possible that the CdS/CuInSe{sub 2} device is a buried, shallow junction with a CdS window layer, rather than a heterojunction. We have used these ideas to develop methods for fabricating devices without CdS or Cd. A 14.2% efficiency ZnO/CIGS device was obtained through aqueous treatment in Zn solutions.

  7. SU-8 as Hydrophobic and Dielectric Thin Film in Electrowetting-on-Dielectric Based Microfluidics Device

    OpenAIRE

    Vijay Kumar; N. N. Sharma

    2012-01-01

    Electrowetting-on-dielectric (EWOD) based droplet actuation in microfluidic chip is designed and fabricated. EWOD is used as on-chip micro-pumping scheme for moving fluid digitally in Lab-on-a-chip devices. For enabling this scheme, stacked deposition of thin dielectric and hydrophobic layer in that order between microchannel and electrodes is done. The present paper investigates the potential use of SU-8 as hydrophobic layer in conjunction of acting as dielectric in the device. The objective...

  8. Development of Novel Magnetic Metal Oxide Thin Films and Carbon Nanotube Materials for Potential Device Applications

    Science.gov (United States)

    2016-05-09

    materials with applications in areas such as magnetic recording, magnetic sensing devices and high frequency planar microwave devices. Emphasis has been... emission SEM/STEM. For STEM imaging, some nanotubes were scrapped off SiO2 substrate and dispersed in dimethylformamide the resulting solution was dripped...on holey carbon coated carbon TEM grid for SEM and STEM analysis. VSM measurements were carried out using Vector Magnetometer Model 10 VSM system

  9. Design, fabrication, and characterization of electroless Ni–P alloy films for micro heating devices

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bernard Haochih, E-mail: hcliu@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Taiwan (China); Promotion Center for Global Materials Research, National Cheng Kung University, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Taiwan (China); Liao, Fang-Yi; Chen, Jian-Hong [Department of Materials Science and Engineering, National Cheng Kung University, Taiwan (China)

    2013-06-30

    In this work electroless nickel–phosphorous coatings were used as the micro heaters for scanning thermal microscopy. The deposition of Ni–P alloys not only simplified the microelectromechanical system fabrication steps but also provided flexibility in the tuning of the resistance of the heating elements. Ni–P films were plated on patterned silicon substrates and silicon with a silicon nitride film. The pre-deposition reactive ion etch (RIE) treatment caused a change in surface roughness that enhanced the adhesion of Ni–P coatings. Optimization of RIE parameters and pH values could achieve selective deposition of Ni–P, thus helped the lift-off of a serpentine circuit pattern. The chemical composition and microstructure of Ni–P films affect the electrical properties of micro heaters. Energy-dispersive X-ray spectroscopy identified the Ni–P composition and confirmed its insignificant level of oxidation. The high-temperature X-ray diffraction indicated that the as-deposited film was crystalline Ni, which later transformed into Ni{sub 3}P at higher temperature. The resistivity of Ni–P films was tailored between 10{sup −5} and 10{sup −7} Ω m via a post-deposition annealing, which also obtained a stable temperature coefficient of resistance. Consequently, the performance of micro heaters could be designed with a high degree of flexibility. - Highlights: • We developed a process to fabricate micro heater by Ni–P electroless plating. • Reactive ion etch caused oscillating surface roughness and affected Ni–P adhesion. • Ni{sub 3}P phase precipitates during annealing and reduces resistivity of Ni–P alloys. • Resistivity of Ni–P is tunable from 10{sup −5} to 10{sup −7} Ω m by plating and annealing.

  10. Ti/Cu bilayer electrodes for SiNx-passivated Hf-In-Zn-O thin film transistors: Device performance and contact resistance

    Science.gov (United States)

    Park, Joon Seok; Kim, Tae Sang; Son, Kyoung Seok; Lee, Eunha; Jung, Ji Sim; Lee, Kwang-Hee; Maeng, Wan-Joo; Kim, Hyun-Suk; Kim, Eok Su; Park, Kyung-Bae; Kwon, Jang-Yeon; Ryu, Myung Kwan; Lee, Sang Yoon

    2010-10-01

    In this study, we examine the possibility of using Ti/Cu bilayer as source/drain electrodes for SiNx-passivated Hf-In-Zn-O (HIZO) thin film transistors by comparing their electrical properties with devices that use Mo electrodes. The Mo devices operate in depletion mode with a higher field effect mobility, while the Ti/Cu devices exhibit an improved subthreshold swing and operate in enhancement mode. Transmission electron microscopy characterization reveals the formation of an amorphous TiOx layer at the Ti/HIZO interface, which is suggested to be responsible for the disparate device characteristics in terms of contact resistance and threshold delay.

  11. Structural and magnetic properties of Ni78Fe22 thin films sandwiched between low-softening-point glasses and application in spin devices

    Science.gov (United States)

    Misawa, Takahiro; Mori, Sumito; Komine, Takashi; Fujioka, Masaya; Nishii, Junji; Kaiju, Hideo

    2016-12-01

    We investigate the structural and magnetic properties of Ni78Fe22 thin films sandwiched between low-softening-point (LSP) glasses, which can be used in spin quantum cross (SQC) devices utilizing stray magnetic fields generated from magnetic thin-film edges. We also calculate the stray magnetic field generated between the two edges of Ni78Fe22 thin-film electrodes in SQC devices and discuss the applicability to spin-filter devices. Using the established fabrication technique, we successfully demonstrate the formation of LSP-glass/Ni78Fe22/LSP-glass structures with smooth and clear interfaces. The coercivity of the Ni78Fe22 thin films is enhanced from 0.9 to 103 Oe by increasing the applied pressure from 0 to 1.0 MPa in the thermal pressing process. According to the random anisotropy model, the enhancement of the coercivity is attributed to the increase in the crystal grain size. The stray magnetic field is also uniformly generated from the Ni78Fe22 thin-film edge in the direction perpendicular to the cross section of the LSP-glass/Ni78Fe22/LSP-glass structures. Theoretical calculation reveals that a high stray field of approximately 5 kOe is generated when the distance between two edges of the Ni78Fe22 thin-film electrodes is less than 5 nm and the thickness of Ni78Fe22 is greater than 20 nm. These experimental and calculation results indicate that Ni78Fe22 thin films sandwiched between LSP glasses are useful as electrodes for SQC devices, serving as spin-filter devices.

  12. An overview of micro-optical components and system technology: bulk, planar, and thin-film for laser initiated devices

    Science.gov (United States)

    Lizotte, Todd

    2010-08-01

    There are a number of attractive micro optical elements or combinations of elements that are currently used or could be employed in optically initiated ordnance systems. When taking a broad-spectrum examination of optically initiated devices, the required key parameters become obviously straightforward for micro optics. Plainly stated, micro optics need to be simple, inexpensive, reliable, robust and compatible within their operational environment. This presentation focuses on the variety of optical elements and components available in the market place today that could be used to realize micro-optical beam shaping and delivery systems for optically initiated devices. A number of micro optical elements will be presented with specific bulk, planar optical and thin film optical devices, such as diffractive optics, micro prisms, axicons, waveguides, micro lenses, beam splitters and gratings. Further descriptions will be presented on the subject of coupling light from a laser beam into a multimode optical fiber. The use of micro optics for collimation of the laser source and conditioning of the laser beam to achieve the highest efficiency and matching the optical fiber NA will be explained. An emphasis on making these optical assemblies compact and rugged will be highlighted.

  13. Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.

    Science.gov (United States)

    Han, Lihao; Abdi, Fatwa F; van de Krol, Roel; Liu, Rui; Huang, Zhuangqun; Lewerenz, Hans-Joachim; Dam, Bernard; Zeman, Miro; Smets, Arno H M

    2014-10-01

    A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell.

  14. Effects of ZnS:Mn/AlN multilayer structure on luminescent properties of nanostructured thin-film EL device

    Science.gov (United States)

    Adachi, Daisuke; Takei, Kohei; Toyama, Toshihiko; Okamoto, Hiroaki

    2007-10-01

    Effects of ZnS:Mn/AlN multilayer structure on luminescent properties of nanostructured (NS) thin-film electroluminescent (TFEL) device of which emission layer is a multilayer composed with ZnS:Mn layers and 0.7-nm-thick AlN interlayers were studied. The bandgap widening and the increased PL efficiency of Mn 2+ 3d-3d transitions with a decrease in the ZnS:Mn single-layer thickness down to 5 nm were observed, which is ascribed to quantum confinement effects. Meanwhile, the multilayer with 2-nm-thick ZnS:Mn single-layers shows a drop of PL efficiency, indicating the presence of defective region just on AlN. The tendency of the luminous efficiency of the NS-TFEL device against the ZnS:Mn single-layer thickness is similar to the tendency found in the PL efficiency, indicating the importance of the ZnS:Mn/AlN interface for the device performance.

  15. Characterizations and thermal stability improvement of phase-change memory device containing Ce-doped GeSbTe films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yu-Jen; Tsai, Min-Chuan; Wang, Chiung-Hsin; Hsieh, Tsung-Eong, E-mail: tehsieh@mail.nctu.edu.tw

    2012-02-29

    Phase-transition temperature of GeSbTe (GST) chalcogenide film was drastically increased from 159 to 236 Degree-Sign C by cerium (Ce) doping (up to 8.6 at.%) without altering the resistivity property of GST. Grain refinement via the solid-solution mechanism and the amplification of p-type semiconducting behavior in Ce-doped GST were observed. They were correlated with the enhancement of thermal stability and data retention property of GST as revealed by exothermal and isothermal analyses. Phase-change memory (PCM) device characterized at various temperatures revealed an effective thermal stability improvement on the threshold voltage of PCM device by Ce doping. - Highlights: Black-Right-Pointing-Pointer Ce doping increased phase-change temperature of GST from 159 to 236 Degree-Sign C. Black-Right-Pointing-Pointer No suppression of resistivity level in amorphous Ce-doped GST. Black-Right-Pointing-Pointer Resistance ratio of amorphous and crystalline Ce-doped GST was preserved at 10{sup 5}. Black-Right-Pointing-Pointer p-type semiconducting behavior of GST was enhanced by Ce-doping. Black-Right-Pointing-Pointer Ce-doping improved the thermal stability of threshold voltage of GST PCM device.

  16. Effect of sputtering power on crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO transparent conducting thin films for optoelectronic devices

    Science.gov (United States)

    Hu, Yu Min; Li, Jung Yu; Chen, Nai Yun; Chen, Chih Yu; Han, Tai Chun; Yu, Chin Chung

    2017-02-01

    The crystallinity and intrinsic defects of transparent conducting oxide (TCO) films have a high impact on their optical and electrical properties and therefore on the performance of devices incorporating such films, including flat panel displays, electro-optical devices, and solar cells. The optical and electrical properties of TCO films can be modified by tailoring their deposition parameters, which makes proper understanding of these parameters crucial. Magnetron sputtering is the most adaptable method for preparing TCO films used in industrial applications. In this study, we investigate the direct and inter-property correlation effects of sputtering power (PW) on the crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO (AZO) TCO films. All of the films were preferentially c-axis-oriented with a wurtzite structure and had an average transmittance of over 80% in the visible wavelength region. Scanning electron microscopy images revealed significantly increased AZO film grain sizes for PW ≥ 150 W, which may lead to increased conductivity, carrier concentration, and optical band gaps but decreased carrier mobility and in-plane compressive stress in AZO films. Photoluminescence results showed that, with increasing PW, the near band edge emission gradually dominates the defect-related emissions in which zinc interstitial (Zni), oxygen vacancy (VO), and oxygen interstitial (Oi) are possibly responsible for emissions at 3.08, 2.8, and 2.0 eV, respectively. The presence of Zni- and Oi-related emissions at PW ≥ 150 W indicates a slight increase in the presence of Al atoms substituted at Zn sites (AlZn). The presence of Oi at PW ≥ 150 W was also confirmed by X-ray photoelectron spectroscopy results. These results clearly show that the crystallinity and intrinsic-defect type of AZO films, which dominate their optical and electrical properties, may be controlled by PW. This understanding may facilitate the development of TCO

  17. SU-8 as Hydrophobic and Dielectric Thin Film in Electrowetting-on-Dielectric Based Microfluidics Device

    Directory of Open Access Journals (Sweden)

    Vijay Kumar

    2012-01-01

    Full Text Available Electrowetting-on-dielectric (EWOD based droplet actuation in microfluidic chip is designed and fabricated. EWOD is used as on-chip micro-pumping scheme for moving fluid digitally in Lab-on-a-chip devices. For enabling this scheme, stacked deposition of thin dielectric and hydrophobic layer in that order between microchannel and electrodes is done. The present paper investigates the potential use of SU-8 as hydrophobic layer in conjunction of acting as dielectric in the device. The objective for the investigation is to lower the cost and a thin simplification in fabrication process of EWOD-based devices. We have done design and optimization of dimensions of electrode array including gap between arrays for EWOD micropump. Design and optimization are carried out in CoventorWare. The designing is followed by fabrication of device and analysis for droplet motion. The fabrication of the device includes array of electrodes over the silicon surface and embedding them in hydrophobic SU-8 layer. Water droplet movement in the order of microliter of spherical shape is demonstrated. It has been shown that an SU-8 microchannel in the current design allows microfluidic flow at tens of voltages comparable with costlier and more complicated to fabricate designs reported in the literature.

  18. Synthesis and characterization thin films of conductive polymer (PANI) for optoelectronic device application

    Science.gov (United States)

    Jarad, Amer N.; Ibrahim, Kamarulazizi; Ahmed, Nasser M.

    2016-07-01

    In this work we report preparation and investigation of structural and optical properties of polyaniline conducting polymer. By using sol-gel in spin coating technique to synthesize thin films of conducting polymer polyaniline (PANI). Conducting polymer polyaniline was synthesized by the chemical oxidative polymerization of aniline monomers. The thin films were characterized by technique: Hall effect, High Resolution X-ray diffraction (HR-XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. Polyaniline conductive polymer exhibit amorphous nature as confirmed by HR-XRD. The presence of characteristic bonds of polyaniline was observed from FTIR spectroscopy technique. Electrical and optical properties revealed that (p-type) conductivity PANI with room temperature, the conductivity was 6.289×10-5 (Ω.cm)-1, with tow of absorption peak at 426,805 nm has been attributed due to quantized size of polyaniline conducting polymer.

  19. A Simple Substrate Heater Device With Temperature Controller for Thin Film Preparation

    Directory of Open Access Journals (Sweden)

    G. Rendón

    2012-08-01

    Full Text Available A simple substrate heater and its temperature controller were designed and built in order to prepare thin films in a highvacuum deposition system. The substrate heater was elaborated with a glass-ceramic body and a molybdenum foilheater. The applied power and the temperature are regulated by a power controller board using a microcontrollerprogrammed with a proportional-integrative-derivative algorithm. The heater/controller system was tested in a highvacuum deposition system and the results of its characterization at 100, 200, 300 and 400 °C are presented. Avariation in temperature better than ± 0.5 °C was obtained for all the tested temperatures. An application of thesubstrate heater is demonstrated by evaporating gold thin films on heated glass substrates.

  20. Synthesis and characterization thin films of conductive polymer (PANI) for optoelectronic device application

    Energy Technology Data Exchange (ETDEWEB)

    Jarad, Amer N., E-mail: amer78malay@yahoo.com.my; Ibrahim, Kamarulazizi, E-mail: kamarul@usm.my; Ahmed, Nasser M., E-mail: nas-tiji@yahoo.com [Nano-optoelectronic Research and Technology Laboratory School of physics, University of Sains Malaysia, 11800 Pulau Pinang (Malaysia)

    2016-07-06

    In this work we report preparation and investigation of structural and optical properties of polyaniline conducting polymer. By using sol-gel in spin coating technique to synthesize thin films of conducting polymer polyaniline (PANI). Conducting polymer polyaniline was synthesized by the chemical oxidative polymerization of aniline monomers. The thin films were characterized by technique: Hall effect, High Resolution X-ray diffraction (HR-XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. Polyaniline conductive polymer exhibit amorphous nature as confirmed by HR-XRD. The presence of characteristic bonds of polyaniline was observed from FTIR spectroscopy technique. Electrical and optical properties revealed that (p-type) conductivity PANI with room temperature, the conductivity was 6.289×10{sup −5} (Ω.cm){sup −1}, with tow of absorption peak at 426,805 nm has been attributed due to quantized size of polyaniline conducting polymer.

  1. Low electrical resistivity polycrystalline SiGe films obtained by vertical LPCVD for MOS devices

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Ricardo Cotrin [State University of Campinas (UNICAMP), Center for Semiconductor Components (CCS), School of Electrical and Computer Engineering - FEEC, Rua Joao Pandia Calogeras, 90 Caixa Postal 6061, CEP 13083-870 Campinas-SP (Brazil); Doi, Ioshiaki [State University of Campinas (UNICAMP), Center for Semiconductor Components (CCS), School of Electrical and Computer Engineering - FEEC, Rua Joao Pandia Calogeras, 90 Caixa Postal 6061, CEP 13083-870 Campinas-SP (Brazil)]. E-mail: doi@led.unicamp.br; Zakia, Maria Beny Pinto [State University of Campinas (UNICAMP), Center for Semiconductor Components (CCS), School of Electrical and Computer Engineering - FEEC, Rua Joao Pandia Calogeras, 90 Caixa Postal 6061, CEP 13083-870 Campinas-SP (Brazil); Diniz, Jose Alexandre [State University of Campinas (UNICAMP), Center for Semiconductor Components (CCS), School of Electrical and Computer Engineering - FEEC, Rua Joao Pandia Calogeras, 90 Caixa Postal 6061, CEP 13083-870 Campinas-SP (Brazil); Swart, Jacobus Willibrordus [State University of Campinas (UNICAMP), Center for Semiconductor Components (CCS), School of Electrical and Computer Engineering - FEEC, Rua Joao Pandia Calogeras, 90 Caixa Postal 6061, CEP 13083-870 Campinas-SP (Brazil)

    2005-12-05

    In this study, authors present some morphological and electrical characterization of polycrystalline SiGe thin films (poly-SiGe) deposited by vertical LPCVD using SiH{sub 4}, GeH{sub 4} and H{sub 2} mixture in different deposition parameters aiming for MOS gate electrodes. The obtained thin films are very uniform and smooth, with small grain size, feasible to deep submicrom fabrication. The SiGe samples presented resistivity values as low as 0.42 m{omega} cm, one order of magnitude lower than poly-Si reference samples. CV and IV measurements points this poly-SiGe as a suitable material for MOS gate electrodes.

  2. Microwave Magnetic Materials for Radar and Signal Processing Devices - Thin Film and Bulk Oxides and Metals

    Science.gov (United States)

    2007-11-29

    The spin wave bands that result from a full solution of Maxwell’s equations and the linear-Figure 1 shows representative measurement results on the... equation based on a so-called continuum The experiment used a magnetic film strip-based active approximation and numerically discovered solitons. In...propagation of spin waves a large-amplitude periodic wave described by the KdV 17,81. The propagation geometry was chosen to give an equation can break

  3. Thickness and annealing effects on thermally evaporated InZnO thin films for gas sensors and blue, green and yellow emissive optical devices

    Science.gov (United States)

    Sugumaran, Sathish; Jamlos, Mohd Faizal; Ahmad, Mohd Noor; Bellan, Chandar Shekar; Sivaraj, Manoj

    2016-08-01

    Indium zinc oxide (InZnO) thin films with thicknesses of 100 nm and 200 nm were deposited on glass plate by thermal evaporation technique. Fourier transform infrared spectra showed a strong metal-oxide bond. X-ray diffraction patterns revealed amorphous nature for as-deposited film whereas polycrystalline structure for annealed films. Scanning electron microscope images showed a uniform distribution of spherical shape grains. Grain size was found to be higher for 200 nm film than 100 nm film. The presence of elements (In, Zn and O) was confirmed from energy dispersive X-ray analysis. Photoluminescence study of 200 nm film showed a blue, blue-green and blue-yellow emission whereas 100 nm film showed a broad green and green-yellow emissions. Both 100 nm and 200 nm films showed good oxygen sensitivity from room temperature to 400 °C. The observed optical and sensor results indicated that the prepared InZnO films are highly potential for room temperature gas sensor and blue, green and yellow emissive opto-electronic devices.

  4. Growth of a single-wall carbon nanotube film and its patterning as an n-type field effect transistor device using an integrated circuit compatible process

    Energy Technology Data Exchange (ETDEWEB)

    Shiau, S H; Gau, C [Institute of Aeronautics and Astronautics, and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, Taiwan (China); Liu, C W; Dai, B T [National Nano Device Laboratories, No. 27, Nanke 3rd Road, Science-based Industrial Park, Hsin-shi, Tainan, Taiwan (China)], E-mail: gauc@mail.ncku.edu.tw

    2008-03-12

    This study presents the synthesis of a dense single-wall carbon nanotube (SWNT) network on a silicon substrate using alcohol as the source gas. The nanosize catalysts required are made by the reduction of metal compounds in ethanol. The key point in spreading the nanoparticles on the substrate, so that the SWNT network can be grown over the entire wafer, is making the substrate surface hydrophilic. This SWNT network is so dense that it can be treated like a thin film. Methods of patterning this SWNT film with integrated circuit compatible processes are presented and discussed for the first time in the literature. Finally, fabrication and characteristic measurements of a field effect transistor (FET) using this SWNT film are also demonstrated. This FET is shown to have better electronic properties than any other kind of thin film transistor. This thin film with good electronic properties can be readily applied in the processing of many other SWNT electronic devices.

  5. Preparation of Cd(Zn)Te and CuInSe sub 2 films and devices by a two-stage process

    Energy Technology Data Exchange (ETDEWEB)

    Basol, B.M.; Kapur, V.K. (International Solar Electric Technology (ISET), Inglewood, CA (USA))

    1991-05-01

    The two-stage process was used to prepare thin films of Cd(Zn)Te and CuInSe{sub 2}. The technique involves first depositing the elemental components of the compound onto a substrate in the form of thin stacked layers and then reacting these elemental components to obtain a thin film of the desired compound. While CdTe films grown on thin CdS layers have uniform stoichiometries and sharp interfaces with the underlying CdS layers, CdZnTe films deposited onto similar substrates give rise to diffused CdZnTe-CdS interfaces because of the reactive nature of zinc. In CuInSe{sub 2} processing, the nature of the reacted compound film strongly depends on the nature of the Cu-In layers. CdS/CuInSe{sub 2} device efficiencies are also influenced by the method of deposition for the CdS window layers. (orig.).

  6. Hydrogen doped thin film diamond. Properties and application for electronic devices

    CERN Document Server

    Looi, H J

    2000-01-01

    generation remains unknown and based on the experimental results in this work, a model is proposed. The Hall measurements conducted on this conductive layer revealed a p-type nature with promising properties for electronic device application. A more detail study based on electrical and surface science methods were carried out to identify the stability and operating conditions for this dopant. The properties of metal-semiconductor contacts on these surfaces were investigated. The fundamental knowledge is essential for exploring more advanced electronic devices such as the field effect transistors (FETs). Diamond is the only material suitable for detecting UV in the 220nm wavelength without any appreciable visible response. The prospect of introducing a doped layer based on Schottky mode for UV detection is important as it allows monolithic integration with other electronic devices. The face centered cubic allotrope of carbon, diamond, is a semiconducting material which possesses a valuable combination of extre...

  7. Epitaxial growth of group III-nitride films by pulsed laser deposition and their use in the development of LED devices

    Science.gov (United States)

    Li, Guoqiang; Wang, Wenliang; Yang, Weijia; Wang, Haiyan

    2015-11-01

    Recently, pulsed laser deposition (PLD) technology makes viable the epitaxial growth of group III-nitrides on thermally active substrates at low temperature. The precursors generated from the pulsed laser ablating the target has enough kinetic energy when arriving at substrates, thereby effectively suppressing the interfacial reactions between the epitaxial films and the substrates, and eventually makes the film growth at low temperature possible. So far, high-quality group III-nitride epitaxial films have been successfully grown on a variety of thermally active substrates by PLD. By combining PLD with other technologies such as laser rastering technique, molecular beam epitaxy (MBE), and metal-organic chemical vapor deposition (MOCVD), III-nitride-based light-emitting diode (LED) structures have been realized on different thermally active substrates, with high-performance LED devices being demonstrated. This review focuses on the epitaxial growth of group III-nitrides on thermally active substrates by PLD and their use in the development of LED devices. The surface morphology, interfacial property between film and substrate, and crystalline quality of as-grown group III-nitride films by PLD, are systematically reviewed. The corresponding solutions for film homogeneity on large size substrates, defect control, and InGaN films growth by PLD are also discussed in depth, together with introductions to some newly developed technologies for PLD in order to realize LED structures, which provides great opportunities for commercialization of LEDs on thermally active substrates.

  8. In Situ Tuning of Magnetization and Magnetoresistance in Fe3O4 Thin Film Achieved with All-Solid-State Redox Device.

    Science.gov (United States)

    Tsuchiya, Takashi; Terabe, Kazuya; Ochi, Masanori; Higuchi, Tohru; Osada, Minoru; Yamashita, Yoshiyuki; Ueda, Shigenori; Aono, Masakazu

    2016-01-26

    An all-solid-state redox device composed of Fe3O4 thin film and Li(+) ion conducting solid electrolyte was fabricated for use in tuning magnetization and magnetoresistance (MR), which are key factors in the creation of high-density magnetic storage devices. Electrical conductivity, magnetization, and MR were reversibly tuned by Li(+) insertion and removal. Tuning of the various Fe3O4 thin film properties was achieved by donation of an electron to the Fe(3+) ions. This technique should lead to the development of spintronics devices based on the reversible switching of magnetization and spin polarization (P). It should also improve the performance of conventional magnetic random access memory (MRAM) devices in which the ON/OFF ratio has been limited to a small value due to a decrease in P near the tunnel barrier.

  9. A thick-film sensor as a novel device for determination of polyphenols and their antioxidant capacity in white wine.

    Science.gov (United States)

    Photinon, Kanokorn; Chalermchart, Yongyuth; Khanongnuch, Chartchai; Wang, Shih-Han; Liu, Chung-Chiun

    2010-01-01

    A thick-film electrochemical sensor with an iridium-carbon working electrode was used for determining polyphenols and their antioxidant capacity in white wine. Caffeic acid was used as a model species because it has the ability to produce the highest oxidation current. The correlation coefficient of 0.9975 was obtained between sensor response and caffeic acid content. The total phenolic content (TPC) and scavenging activity on 1,1-diphenyl-2-pycrylhydrazyl (DPPH·) radical were also found to be strongly correlated with the concentration of caffeic acid, with a correlation coefficient of 0.9823 and 0.9958, respectively. The sensor prototype was proven to be a simple, efficient and cost effective device to evaluate the antioxidant capacity of substances.

  10. Pulsed laser deposition of piezoelectric ZnO thin films for bulk acoustic wave devices

    Energy Technology Data Exchange (ETDEWEB)

    Serhane, Rafik, E-mail: rserhane@cdta.dz [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Abdelli-Messaci, Samira; Lafane, Slimane; Khales, Hammouche; Aouimeur, Walid [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Hassein-Bey, Abdelkadder [Centre for Development of Advanced Technologies, Cité 20 Août 1956, Baba Hassen, BP: 17, DZ-16303 Algiers (Algeria); Micro and Nano Physics Group, Faculty of Sciences, University Saad Dahlab of Blida (USDB), BP. 270, DZ-09000 Blida (Algeria); Boutkedjirt, Tarek [Equipe de Recherche Physique des Ultrasons, Faculté de Physique, Université des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32, El-Alia, Bab-Ezzouar, DZ-16111 Algiers (Algeria)

    2014-01-01

    Piezoelectric properties of ZnO thin films have been investigated for micro-electro-mechanical systems (MEMS). Wurtzite ZnO structure was prepared on different substrates (Si (1 0 0), Pt (1 1 1)/Ti/SiO{sub 2}/Si and Al (1 1 1)/SiO{sub 2}/Si) at different substrate temperatures (from 100 to 500 °C) by a pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for various piezoelectric applications. Scanning electron microscopy (SEM) showed evidence of honeycomb-like structure on the surface and columnar structure on the cross-section. In the case of ZnO on Al, ZnO exhibited an amorphous phase at the ZnO/Al interface. The XRD measurements indicated that the substrate temperature of 300 °C was the optimum condition to obtain high quality (strongest (0 0 2) peak with the biggest associated grain size) of crystalline ZnO on Pt and on Al and that 400 °C was the optimum one on Si. ZnO on Al exhibits smallest rocking curve width than on Pt, leading to better crystalline quality. The ZnO films were used in bulk acoustic wave (BAW) transducer. Electrical measurements of the input impedance and S-Parameters showed evidence of piezoelectric response. The electromechanical coupling coefficient was evaluated as K{sub eff}{sup 2}=5.09%, with a quality factor Q{sub r} = 1001.4.

  11. Pulsed laser deposition of piezoelectric ZnO thin films for bulk acoustic wave devices

    Science.gov (United States)

    Serhane, Rafik; Abdelli-Messaci, Samira; Lafane, Slimane; Khales, Hammouche; Aouimeur, Walid; Hassein-Bey, Abdelkadder; Boutkedjirt, Tarek

    2014-01-01

    Piezoelectric properties of ZnO thin films have been investigated for micro-electro-mechanical systems (MEMS). Wurtzite ZnO structure was prepared on different substrates (Si (1 0 0), Pt (1 1 1)/Ti/SiO2/Si and Al (1 1 1)/SiO2/Si) at different substrate temperatures (from 100 to 500 °C) by a pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for various piezoelectric applications. Scanning electron microscopy (SEM) showed evidence of honeycomb-like structure on the surface and columnar structure on the cross-section. In the case of ZnO on Al, ZnO exhibited an amorphous phase at the ZnO/Al interface. The XRD measurements indicated that the substrate temperature of 300 °C was the optimum condition to obtain high quality (strongest (0 0 2) peak with the biggest associated grain size) of crystalline ZnO on Pt and on Al and that 400 °C was the optimum one on Si. ZnO on Al exhibits smallest rocking curve width than on Pt, leading to better crystalline quality. The ZnO films were used in bulk acoustic wave (BAW) transducer. Electrical measurements of the input impedance and S-Parameters showed evidence of piezoelectric response. The electromechanical coupling coefficient was evaluated as Keff2    =    5 .0 9 %, with a quality factor Qr = 1001.4.

  12. Blue electroluminescence of ZnSe thin film in an organic-inorganic heterostructures device

    Energy Technology Data Exchange (ETDEWEB)

    Yu Wenge [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China) and Changchun Institute of Optics and Fine Mechanics and Physics, CAS, Changchun 130021 (China) and Shenyang Institute of Aeronautical Engineering, Shenyang 110034 (China)]. E-mail: yu_wenge@hotmail.com; Xu Zheng [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Teng, Feng [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Yang Shengyi [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Hou Yanbing [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Qian Lei [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Qu Chong [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Quan Sanyu [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Xu Xurong [Institute of Optoelectronics, Beijing Jiaotong University, Beijing 100044 (China); Changchun Institute of Optics and Fine Mechanics and Physics, CAS, Changchun 130021 (China)

    2005-05-02

    Blue light emission of ZnSe thin film from the ZnSe/poly-(N-vinyl-carbazole) (PVK) heterostructures was obtained. The threshold voltage is about 10 V and the brightness of 12 cd/m{sup 2} was obtained at 17 V. From the electroluminescence (EL), the photoluminescence (PL), the transient electroluminescence and the dependence of EL intensity on the applied voltage and current, we attribute the EL of ZnSe to carrier injection and recombination. This new phenomenon not only opens a new mechanism of II-IV compounds in low voltage injection EL but also provides a new way of obtaining blue emission.

  13. Recrystallization method to selenization of thin-film Cu(In,Ga)Se.sub.2 for semiconductor device applications

    Science.gov (United States)

    Albin, David S.; Carapella, Jeffrey J.; Tuttle, John R.; Contreras, Miguel A.; Gabor, Andrew M.; Noufi, Rommel; Tennant, Andrew L.

    1995-07-25

    A process for fabricating slightly Cu-poor thin-films of Cu(In,Ga)Se.sub.2 on a substrate for semiconductor device applications includes the steps of forming initially a slightly Cu-rich, phase separated, mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se on the substrate in solid form followed by exposure of the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture to an overpressure of Se vapor and (In,Ga) vapor for deposition on the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture while simultaneously increasing the temperature of the solid mixture toward a recrystallization temperature (about 550.degree. C.) at which Cu(In,Ga)Se.sub.2 is solid and Cu.sub.x Se is liquid. The (In,Ga) flux is terminated while the Se overpressure flux and the recrystallization temperature are maintained to recrystallize the Cu.sub.x Se with the (In, Ga) that was deposited during the temperature transition and with the Se vapor to form the thin-film of slightly Cu-poor Cu.sub.x (In,Ga).sub.y Se.sub.z. The initial Cu-rich, phase separated large grain mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se can be made by sequentially depositing or co-depositing the metal precursors, Cu and (In, Ga), on the substrate at room temperature, ramping up the thin-film temperature in the presence of Se overpressure to a moderate anneal temperature (about 450.degree. C.) and holding that temperature and the Se overpressure for an annealing period. A nonselenizing, low temperature anneal at about 100.degree. C. can also be used to homogenize the precursors on the substrates before the selenizing, moderate temperature anneal.

  14. Solid state molecular device based on a rhenium(I) polypyridyl complex immobilized on TiO2 films.

    Science.gov (United States)

    Patrocinio, Antonio Otavio T; Frin, Karina P M; Murakami Iha, Neyde Y

    2013-05-20

    The photochemical and photophysical behaviors of fac-[Re(CO)3(phen)(trans-stpyCOOH)](+) (phen = 1,10-phenanthroline, trans-stpyCOOH = 4-[trans-(pyridin-4-yl-vinyl)]benzoic acid) in acetonitrile solution and adsorbed on a TiO2 film have been investigated. The trans-to-cis photoisomerization at 404 nm irradiation of coordinated stpyCOOH occurs efficiently in fluid solution as shown by quantum yield determined spectrophotometrically (Φ(UV-vis) = 0.37 ± 0.04) and, more accurately, by (1)H NMR (Φ(NMR) = 0.48 ± 0.04), following the photoproduct signals in the distinct region of the reactant. For the first time, the trans-to-cis isomerization is also reported for the complex adsorbed on the TiO2 surface (Φ(UV-vis) = 0.23 ± 0.03). The photoproduct, fac-[Re(CO)3(phen)(cis-stpyCOOH)](+), is emissive in acetonitrile (ϕ = 0.032), but its radiative decay is highly quenched on the oxide surface by electron photoinjection into the semiconductor, leading to an increasing photocurrent as the trans-to-cis isomerization takes place. Therefore, the photoinduced trans-to-cis isomerization of coordinated ligand immobilized on TiO2 films acts as a trigger for the electron injection process. This system exemplifies the use of photoinduced molecular motion to yield electrical current, which can be used as a "proof of concept" for molecular machines/devices.

  15. Spectroscopic investigation of the chemical and electronic properties of chalcogenide materials for thin-film optoelectronic devices

    Science.gov (United States)

    Horsley, Kimberly Anne

    Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials. For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe 2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These techniques enabled the investigation of the chemical and electronic structure of the materials, both at the surface and towards the bulk. CdS/Cu(In,Ga)Se2 thin-films produced from the roll-to-roll, ambient pressure, Nanosolar industrial line were studied. While record-breaking efficiency cells are usually prepared in high-vacuum (HV) or ultra-high vacuum (UHV) environments, these samples demonstrate competitive mass-production efficiency without the high-cost deposition environment. We found relatively low levels of C contaminants, limited Na and Se oxidation, and a S-Se intermixing at the CdS/CIGSe interface. The surface band gap compared closely to previously investigated CIGSe thin-films deposited under vacuum, illustrating that roll-to-roll processing is a promising and less-expensive alternative for solar cell production. An alternative deposition process for CuInSe2 was also studied, in collaboration with the University of Luxembourg. CuInSe2 absorbers were prepared with varying Cu content and surface treatments to investigate the potential to produce an absorber with a Cu-rich bulk and Cu-poor surface. This is desired to combine the bulk characteristics of reduced defects and larger grains in Cu-rich films, while maintaining

  16. Effect of heat processing and storage time on migration of bisphenol A (BPA) and bisphenol A-diglycidyl ether (BADGE) to aqueous food simulant from Mexican can coatings.

    Science.gov (United States)

    Munguia-Lopez, E M; Soto-Valdez, H

    2001-08-01

    Effects of heat processing and storage time (up to 70 days) on migration of bisphenol A (BPA) and bisphenol A-diglycidyl ether (BADGE) from can coatings into an aqueous food simulant were determined. Distilled water was canned in two types of Mexican cans: for tuna and for jalapeño peppers. Results showed that there is an effect of heat treatment on migration of both compounds. Storage time did not show any effect in BPA migration from tuna cans. There was an effect of storage time on BPA migration from jalapeño pepper cans. Results for BADGE migration were affected by its susceptibility to hydrolyze in aqueous simulants. BADGE concentration decreased, or was not detected, during storage in both types of cans. Migration levels for BPA and BADGE were within 0.6-83.4 and Mercosur legislation limits. Other migrating compounds were detected, although no identification was performed.

  17. Plasma processing of niobium for the production of thin-film superconducting devices

    Energy Technology Data Exchange (ETDEWEB)

    Tugwell, A.J.; Hutson, D.; Pegrum, C.M.; Donaldson, G.B.

    1987-01-01

    Josephson junctions, which are regions of weak electrical connection between two superconductors, are the active elements of very sensitive thin-film magnetometers. Junctions are fabricated by growing barriers of native oxide on thin Nb films and depositing a layer of PbIn alloy on top. High sensitivity magnetometers require junctions of small area, and to achieve this, edge junctions are fabricated in which one dimension is defined by the thickness of the Nb and the other is set by the limit of optical lithography. An edge with a suitable angle is produced by reactive ion etching using 5 vol % O/sub 2/ in CF/sub 4/ in a parallel plate rf plasma etcher. Details of etch rates and edge profiles are given. The barrier is formed by a cleaning and oxidation process in an rf plasma at a pressure of 10/sup -6/ bar. Details of the design of a purpose built rf cathode and the run-to-run reproducibility of junction characteristics are given. Different oxidation times and bias voltages are necessary to produce a given oxide thickness on a sloping edge of Nb, as compared to a planar surface, and an explanation for this is proposed. Examples are described of magnetometers made using the above processes.

  18. Thin-Film LSCs Based on PMMA Nanohybrid Coatings: Device Optimization and Outdoor Performance

    Directory of Open Access Journals (Sweden)

    S. M. El-Bashir

    2013-01-01

    Full Text Available This study concerns the design optimization of thin-film luminescent solar concentrators (TLSCs based on polymethylmethacrylate (PMMA/silica nanohybrid films doped with coumarin dyestuffs specialized in coloring plastics. Two designs of TLSCs had been prepared and characterized. The first consists of a transparent nanohybrid layer coated on a fluorescent PMMA substrate. The second design is the ordinary configuration in which fluorescent nanohybrid layer is coated on a transparent PMMA substrate. The investigation of the spectral properties and efficiency parameters recommended the best solar energy conversion efficiency for the second design. The outdoor performance of optimized TLSC was also evaluated under clear sky conditions of Riyadh city, and the hourly values of the optical efficiency, ηopt, were calculated for one year. The best performance was achieved in summer since the short circuit current for PV cell was doubled after being attached to TLSC and the value of ηopt reached 40% which is higher than other values recorded before due to the abundant solar energy potential in the Arabian Peninsula.

  19. Development of ruthenium dioxide electrodes for pyroelectric devices based on lithium tantalate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nougaret, Laurianne [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: laurianne.nougaret@univ-montp2.fr; Combette, Philippe [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: philippe.combette@univ-montp2.fr; Arinero, Richard [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: richard.arinero@univ-montp2.fr; Podlecki, Jean [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: jean.podlecki@univ-montp2.fr; Pascal-Delannoy, Frederique [Centre d' Electronique et de Micro-optoelectronique de Montpellier, Unite mixte de Recherche du CNRS no 5507, Universite Montpellier II, Place E. Bataillon, 34095 Montpellier cedex 05 (France)]. E-mail: Frederique.delannoy@univ-montp2.fr

    2007-02-26

    The aim of this paper is the study of ruthenium dioxide (RuO{sub 2}) films, grown on low-stress silicon nitride on silicon (SiN {sub x}/Si), in order to develop thermal micro-sensors based on pyroelectric effect. The active part of these micro-sensors is constituted by a new arrangement : lithium tantalate (LiTaO{sub 3})/RuO{sub 2}/SiN{sub x}/Si. Radio-frequency (RF) sputtering is employed to deposit RuO{sub 2} on SiN {sub x}/Si substrate. Morphology, crystallinity and resistivity of RuO{sub 2} are studied as function of growth parameters. Next, RF magnetron sputtering was used to deposit LiTaO{sub 3} on this electrode. Morphology studies, pyroelectric effect and dielectric parameters obtained, indicate that RuO{sub 2} material is a suitable candidate as back electrode for LiTaO{sub 3} thin films.

  20. SEMICONDUCTOR DEVICES Thin film AlGaInP light emitting diodes with different reflectors

    Science.gov (United States)

    Wei, Gao; Weiling, Guo; Deshu, Zou; Yuan, Qin; Wenjing, Jiang; Guangdi, Shen

    2010-12-01

    The reflectivity versus incident angle of a GaP/Au reflector, a GaP/SiO2/Au triple ODR (omni-directional reflector) and a GaP/ITO/Au triple ODR was calculated. Compared to AlGaInP LEDs with a GaAs absorbing substrate, thin film LEDs with a Au reflector, a SiO2 ODR and an ITO ODR were fabricated. At a current of 20 mA, the optical output power of four samples was respectively 1.04, 1.14, 2.53 and 2.15 mW. The Au diffusion in the annealing process reduces the reflectivity of the Au/GaP reflector to 9%. The different transmittance of quarter-wave thickness ITO and SiO2 induces different optical output power between the SiO2 and ITO thin film LEDs. The insertion of Zn in the ITO ODR LED does not affect the light output but evidently reduces the voltage.

  1. Optoelectronic Devices and Related Physical Phenomena in Thin Film Semiconductor Configurations.

    Science.gov (United States)

    1986-05-01

    Robinson, W. K. Marshall, J. Katz, J. S. Smith, and A. Yariv, " Monolithically Integrated Array of GaAlAs Electroabsorption Modulators," Electron... monolithic array of GaAlAs electroabsorption modulator has been demonstrated by reverse bias operation of the separate contact array. This device may be...Katz, C. Lindsey, S. Margalit, A. Yariv, "Control of Mutual Phase Locking of Monolithically Integrated Semiconductor Lasers," Appl. Phys. Lett., 43

  2. High efficiency, hybrid electrochromic device on polycarbonate substrates with neon sputtered WO3-x thin films

    OpenAIRE

    2016-01-01

    Electrochromic materials change color reversibly by applying an external DC voltage. One among the many emerging application of electro-chromics is the smart windows. The coloration efficiency, the optical colour modulation and the cyclability are the factors that bench mark the device. Tungsten oxide (WO3-x) is versatile material and reactive DC magnetron sputtering (with argon as sputter gas) technique is common for electro-chromics. In the present communication we have prepared tungsten ox...

  3. Single Molecular Precursor Solution for CuIn(S,Se)2 Thin Films Photovoltaic Cells: Structure and Device Characteristics.

    Science.gov (United States)

    Tiwari, Devendra; Koehler, Tristan; Lin, Xianzhong; Sarua, Andrei; Harniman, Robert; Wang, Lan; Klenk, Reiner; Fermin, David J

    2017-01-25

    A single molecular precursor solution is described for the deposition of CuIn(S,Se)2 (CIS) film onto Mo-coated glass substrates by spin coating, followed by annealing in Se atmosphere. Characterization of the films by X-ray diffraction, Raman spectroscopy and scanning electron microscopy demonstrates the formation of a highly homogeneous and compact 1.1 μm thick CIS layer, with a MoSe2 under-layer. Atomic force microscopy reveals the presence of spherical grains between 400 and 450 nm, featuring surface corrugation in the range of 30 nm. Film composition is found to be in close agreement with that of the precursor solution. Diffuse reflectance spectroscopy shows a direct band gap (Eg) of 1.36 eV. Intensity and temperature dependence photoluminescence spectra show characteristic features associated with a donor-acceptor pair recombination mechanism, featuring activation energy of 34 meV. Over 85 solar cell devices with the configuration Mo/CIS/CdS/i-ZnO/Al:ZnO/Ni-Al and an total area of 0.5 cm(2) were fabricated and tested. The champion cell shows a power efficiency of 3.4% with an open circuit voltage of 521 mV and short circuit current of 14 mA/cm(2) under AM 1.5 illumination and an external quantum efficiency above 60%. Overall variation in each of solar cell parameters remains below 10% of the average value, demonstrating the remarkable homogeneity of this solution processing method. To understand the limitation of devices, the dependence of the open-circuit voltage and impedance spectra upon temperature were analyzed. The data reveal that the CuIn(S,Se)2/CdS interface is the main recombination pathway with an activation energy of 0.79 eV as well as the presence of two "bulk" defect states with activation energies of 37 and 122 meV. We also estimated that the MoSe2 under-layer generates back contact barrier of 195 meV.

  4. Chemical etching of Tungsten thin films for high-temperature surface acoustic wave-based sensor devices

    Energy Technology Data Exchange (ETDEWEB)

    Spindler, M., E-mail: m.spindler@ifw-dresden.de [IFW Dresden, SAWLab Saxony, P.O. Box 270116, D-01171 Dresden (Germany); Herold, S.; Acker, J. [BTU Cottbus – Senftenberg, Faculty of Sciences, P.O. Box 101548, 01968 Senftenberg (Germany); Brachmann, E.; Oswald, S.; Menzel, S.; Rane, G. [IFW Dresden, SAWLab Saxony, P.O. Box 270116, D-01171 Dresden (Germany)

    2016-08-01

    Surface acoustic wave devices are widely used as wireless sensors in different application fields. Recent developments aimed to utilize those devices as temperature sensors even in the high temperature range (T > 300 °C) and in harsh environmental conditions. Therefore, conventional materials, which are used for the substrate and for the interdigital transducer finger electrodes such as multilayers or alloys based on Al or Cu have to be exchanged by materials, which fulfill some important criteria regarding temperature related effects. Electron beam evaporation as a standard fabrication method is not well applicable for depositing high temperature stable electrode materials because of their very high melting points. Magnetron sputtering is an alternative deposition process but is also not applicable for lift-off structuring without any further improvement of the structuring process. Due to a relatively high Ar gas pressure of about 10{sup −1} Pa, the sidewalls of the photoresist line structures are also covered by the metallization, which subsequently prevents a successful lift-off process. In this study, we investigate the chemical etching of thin tungsten films as an intermediate step between magnetron sputtering deposition of thin tungsten finger electrodes and the lift-off process to remove sidewall covering for a successful patterning process of interdigital transducers. - Highlights: • We fabricated Tungsten SAW Electrodes by magnetron sputtering technology. • An etching process removes sidewall covering of photoresist, which allows lift-off. • Tungsten etching rates based on a hydrogen peroxide solutions were determined.

  5. Stable protein device platform based on pyridine dicarboxylic acid-bound cubic-nanostructured mesoporous titania films.

    Science.gov (United States)

    Kim, Hwajeong; Park, Sung Soo; Seo, Jooyeok; Ha, Chang-Sik; Moon, Cheil; Kim, Youngkyoo

    2013-08-14

    Here we shortly report a protein device platform that is extremely stable in a buffer condition similar to human bodies. The protein device platform was fabricated by covalently attaching cytochrome c (cyt c) protein molecules to organic coupler molecules (pyridine dicarboxylic acid, PDA) that were already covalently bound to an electron-transporting substrate. A cubic nanostructured mesoporous titania film was chosen as an electron-transporting substrate because of its large-sized cubic holes (∼7 nm) and highly crystalline cubic titania walls (∼0.4 nm lattice). Binding of PDA molecules to the mesoporous titania surface was achieved by esterification reaction between carboxylic acid groups (PDA) and hydroxyl groups (titania) in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) mediator, whereas the immobilization of cyt c to the PDA coupler was carried out by the EDC-mediated amidation reaction between carboxylic acid groups (PDA) and amine groups (cyt c). Results showed that the 2,4-position isomer among several PDAs exhibited the highest oxidation and reduction peak currents. The cyt c-immobilized PDA-bound titania substrates showed stable and durable electrochemical performances upon continuous current-voltage cycling for 240 times (the final current change was less than 3%) and could detect superoxide that is a core indicator for various diseases including cancers.

  6. Electrochromic properties of NiOx:H films deposited by DC magnetron sputtering for ITO/NiOx:H/ZrO2/WO3/ITO device

    Science.gov (United States)

    Dong, Dongmei; Wang, Wenwen; Dong, Guobo; Zhou, Yuliang; Wu, Zhonghou; Wang, Mei; Liu, Famin; Diao, Xungang

    2015-12-01

    NiOx:H thin films were deposited on ITO-coated glass by DC reactive magnetron sputtering at room temperature. The effects of the hydrogen content on the structure, morphologies, electrochemical properties, the stoichiometry and chemical states of NiOx:H thin films were systematically studied. In X-ray diffraction and atomic force microscopy analysis, the crystallinity of the films tends to be weakened when the flow amount ratio of Ar:O2:H2 equals 19:1:3 and as confirmed in electrochemical analysis, such relatively weak crystallinity is the main contributing factor to ion transportation. X-ray photoelectron spectroscopy reveals that the increase of the hydrogen contents results in a relatively lower binding energy exhibited in the Ni 2p spectra. The proportion of Ni2O3 in NiOx:H films increases from 22% at bleached state to 33% at colored state. A monolithic all-thin-film inorganic electrochromic device was fabricated with complementary configuration as ITO/NiOx:H/ZrO2/WO3/ITO. The electrochromic device with optimized NiOx:H thin films acting both as ion storage layer and proton-providing source displays high modulation efficiency of 68% at a fixed wavelength 550 nm.

  7. Printed high-frequency RF identification antenna on ultrathin polymer film by simple production process for soft-surface adhesive device

    Science.gov (United States)

    Hayata, Hiroki; Okamoto, Marin; Takeoka, Shinji; Iwase, Eiji; Fujie, Toshinori; Iwata, Hiroyasu

    2017-05-01

    In this paper, we present a simple method for manufacturing electronic devices using ultrathin polymer films, and develop a high-frequency RF identification. To expand the market for flexible devices, it is important to enhance their adhesiveness and conformability to surfaces, to simplify their fabrication, and to reduce their cost. We developed a method to design an antenna for use on an operable RF identification whose wiring was subjected to commercially available inkjet or simple screen printing, and successfully fabricated the RF identification. By using ultrathin films made of polystyrene-block-polybutadiene-block-polystyrene (SBS) as substrates — less than 750 nm — the films could be attached to various surfaces, including soft surfaces, by van der Waals force and without using glue. We succeeded in the simple fabrication of an ultrathin RF identification including a commercial or simple printing process.

  8. All-printed and transparent single walled carbon nanotube thin film transistor devices

    Science.gov (United States)

    Sajed, Farzam; Rutherglen, Christopher

    2013-09-01

    We present fully transparent single-walled all-carbon nanotube thin film transistors (SWCNT TFT) fabricated using low-cost inkjet printing methods. Such a demonstration provides a platform towards low cost fully printed transparent electronics. The SWCNT TFTs were printed with metallic and semiconducting SWCNT using a room temperature printing process, without the requirement of expensive cleanroom facilities. The unoptimized SWCNT TFTs fabricated exhibited an Ion/off ratio of 92 and mobility of 2.27 cm2V-1s-1 and transmissivity of 82%. The combination of both high electrical performance and high transparency make all-SWCNT TFTs desirable for next generation transparent display backplanes and products such as Google Glass.

  9. Occurrence of phthalate diesters (phthalates), p-hydroxybenzoic acid esters (parabens), bisphenol A diglycidyl ether (BADGE) and their derivatives in indoor dust from Vietnam: Implications for exposure.

    Science.gov (United States)

    Tran, Tri Manh; Minh, Tu Binh; Kumosani, Taha A; Kannan, Kurunthachalam

    2016-02-01

    Phthalate diesters (phthalates), esters of p-hydroxybenzoic acid (parabens), and bisphenol A diglycidyl ether (BADGE) are used in personal care products, food packages, household products, or pharmaceuticals. These compounds possess endocrine-disrupting potentials and have been reported to occur in the environment. Nevertheless, no previous studies have reported the occurrence of these compounds in indoor dust from Vietnam. In this study, nine phthalates, six parabens, and four BADGEs were determined in indoor dust samples collected from Hanoi, Hatinh, Hungyen, and Thaibinh, in Vietnam. Total concentrations of phthalates, parabens, and BADGEs in indoor dust ranged from 3440 to 106,000 ng/g (median: 22,600 ng/g), 40-840 ng/g (median: 123 ng/g), and 23 to 1750 ng/g (median: 184 ng/g), respectively. Based on the measured median concentration of phthalates, parabens, and BADGEs in indoor dust, we estimated human exposure doses to these compounds through indoor dust ingestion for various age groups. The exposure doses to phthalates, parabens, and BADGEs decreased with age and ranged from 19.4 to 90.4 ng/kg-bw/d, 0.113-0.528 ng/kg-bw/d, and 0.158-0.736 ng/kg-bw/d, respectively. This is the first study on the occurrence and human exposure of phthalates, parabens, and BADGEs in indoor dust from Vietnam.

  10. Fabrication of graphene-nanoflake/poly(4-vinylphenol) polymer nanocomposite thin film by electrohydrodynamic atomization and its application as flexible resistive switching device

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyung Hyun; Ali, Junaid [Department of Mechatronics Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Na, Kyoung-Hoan, E-mail: khna@dankook.ac.kr [College of Engineering, Dankook University, Yongin-si, Gyeonggi-do 448-701 (Korea, Republic of)

    2015-10-15

    This paper describes synthesis of graphene/poly(4-vinylphenol) (PVP) nanocomposite and deposition of thin film by electrohydrodynamic atomization (EHDA) for fabrication flexible resistive switching device. EHDA technique proved its viability for thin film deposition after surface morphology analyses by field emission scanning electron microscope (FESEM) and non-destructive 3D Nano-profilometry, as the deposited films were, devoid of abnormalities. The commercially available graphene micro-flakes were exfoliated and broken down to ultra-small (20 nm–200 nm) nano-flakes by ultra-sonication in presence of N-methyl-pyrrolidone (NMP). These graphene nanoflakes with PVP nanocomposite, were successfully deposited as thin films (thickness ~140±7 nm, R{sub a}=2.59 nm) on indium–tin-oxide (ITO) coated polyethylene terephthalate (PET) substrate. Transmittance data revealed that thin films are up to ~87% transparent in visible and NIR region. Resistive switching behaviour of graphene/PVP nanocomposite thin film was studied by using the nanocomposite as active layer in Ag/active layer/ITO sandwich structure. The resistive switching devices thus fabricated, showed characteristic OFF to ON (high resistance to low resistance) transition at low voltages, when operated between ±3 V, characterized at 10 nA compliance currents. The devices fabricated by this approach exhibited a stable room temperature, low power current–voltage hysteresis and well over 1 h retentivity, and R{sub OFF}/R{sub ON}≈35:1. The device showed stable flexibility up to a minimum bending diameter of 1.8 cm.

  11. Study on Wide-gap Gallium-nitride Based Films and Their Quantum-dots Devices

    Science.gov (United States)

    2006-09-05

    propose that the size controlled GaN based quantum dot LED for the prospective white light source cold be used to simulate the sun light for higher Lumen...compositions, the quantum dots of InGaN or InN could emit light to cover the whole visible spectrum. The quantum dot based white light device could...wavelength could be shifted from red to the blue region. The high efficiency, quantum dot size-controlled, white light LED could thus be produced

  12. Influence of Thermal Annealing Treatment on Bipolar Switching Properties of Vanadium Oxide Thin-Film Resistance Random-Access Memory Devices

    Science.gov (United States)

    Chen, Kai-Huang; Cheng, Chien-Min; Kao, Ming-Cheng; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Wu, Sean; Su, Feng-Yi

    2016-12-01

    The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current-voltage (I-V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

  13. Influence of Thermal Annealing Treatment on Bipolar Switching Properties of Vanadium Oxide Thin-Film Resistance Random-Access Memory Devices

    Science.gov (United States)

    Chen, Kai-Huang; Cheng, Chien-Min; Kao, Ming-Cheng; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Wu, Sean; Su, Feng-Yi

    2017-04-01

    The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current-voltage ( I- V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

  14. High Seebeck effects from conducting polymer: Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) based thin-film device with hybrid metal/polymer/metal architecture

    Energy Technology Data Exchange (ETDEWEB)

    Stanford, Michael G [ORNL; Wang, Hsin [ORNL; Ivanov, Ilia N [ORNL; Hu, Bin [University of Tennessee, Knoxville (UTK)

    2012-01-01

    Conductive polymers are of particular interest for thermoelectric applications due to their low thermal conductivity and relatively high electrical conductivity. In this study, commercially available conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used in a hybrid metal/polymer/metal thin film design in order to achieve a high Seebeck coefficient with the value of 252lV/k on a relatively low temperature scale. Polymer film thickness was varied in order to investigate its influence on the Seebeck effect. The high Seebeck coefficient indicates that the metal/polymer/metal design can develop a large entropy difference in internal energy of charge carriers between high and low-temperature metal electrodes to develop electrical potential due to charge transport in conducting polymer film through metal/polymer interface. Therefore, the metal/polymer/metal structure presents a new design to combine inorganic metals and organic polymers in thin-film form to develop Seebeck devices

  15. A Hero’s Maturation in War--On Henry’s Growth in The Red Badge of Courage

    Institute of Scientific and Technical Information of China (English)

    张蓉蓉

    2015-01-01

    Stephen Crane is one of the most famous American writers in late 19th century, and his work of art The Red Badge of Courage is an important masterpiece of naturalism in American literary. With the background of American civil war and the depiction of Henry’s personal experiences and psychological changes durin the war, from inocence to maturation, the author reveals the war’s profound inflence on the charactr’s growth. In this novel, the description of war presents readers a bright war scene. It seems as if the novel is writing about war, in fact, it is exploring the relationship between human and environment, for environment can change a person’s action and mind completely. There is no doubt that The Red Badge of Courage is an excellent novel of war.

  16. A Hero’s Maturation in War——On Henry’s Growth in The Red Badge of Courage

    Institute of Scientific and Technical Information of China (English)

    张蓉蓉

    2015-01-01

    Stephen Crane is one of the most famous American writers in late 19 th century, and his work of art The Red Badge of Courage is an important masterpiece of naturalism in American literary. With the background of American civil war and the depiction of Henry’s personal experiences and psychological changes durin the war, from inocence to maturation, the author reveals the war’s profound inflence on the charactr’s growth. In this novel, the description of war presents readers a bright war scene. It seems as if the novel is writing about war, in fact, it is exploring the relationship between human and environment, for environment can change a person’s action and mind completely. There is no doubt that The Red Badge of Courage is an excellent novel of war.

  17. THz pulse generation using a contact grating device composed of TiO2/SiO2 thin films on LiNbO3 crystal

    Science.gov (United States)

    Yoshida, Fumiko; Nagashima, Keisuke; Tsubouchi, Masaaki; Maruyama, Momoko; Ochi, Yoshihiro

    2016-11-01

    We developed a new contact grating device for terahertz (THz) pulse generation by optical rectification. The device was made from polycrystalline rutile TiO2 thin film in the grating region and an amorphous SiO2 layer deposited on a Mg-doped LiNbO3 crystal. Our calculations indicated that the TiO2 grating on the SiO2 layer would yield an increase in diffraction efficiency of up to 0.69. The prepared TiO2 thin film had a sufficient laser induced damage threshold (140 GW/cm2) to enable effective THz pulse generation. Using a prototype device, we demonstrated THz pulse generation and investigated the phase-matching conditions experimentally.

  18. Corrosion and ion release behavior of Cu/Ti film prepared via physical vapor deposition in vitro as potential biomaterials for cardiovascular devices

    Science.gov (United States)

    Liu, Hengquan; Zhang, Deyuan; Shen, Feng; Zhang, Gui; Song, Shenhua

    2012-07-01

    Cu/Ti films of various Cu/Ti ratios were prepared on a TiNi alloy via vacuum arc plasma deposition. The phase composition, structure, and concentration of elements were investigated via X-ray diffraction and X-photoelectron energy spectrum. The hemolysis ratio and platelet adhesion of the different films were characterized to evaluate blood compatibility. The corrosion and ion release behavior were investigated via a typical immersion test and electrochemical method. The growth of endothelial cells (ECs) was investigated, and methylthiazolyte-trazolium method was employed to evaluate the effect of Cu2+. The sophisticated films showed good compatibility. However, with increasing quality ratio of Cu/Ti, the hemolysis ratio increased, and some platelets started to break slightly. The Cu2+ release was gradually stabilized. The open circuit potential of the Cu/Ti film-modified samples was lower than that of the TiNi substrate. The polarization test result indicates that the passivation stability performance of Cu/Ti film samples is less than the TiNi substrate, and is favorable to Cu2+ release. The adhesion and proliferation of ECs would be inhibited with 10 wt.% Cu concentration of the film, and ECs would undergo apoptosis at >50 wt.% concentration. A Cu/Ti film with good compatibility and anti-endothelialization has potential applications for special cardiovascular devices.

  19. Corrosion and ion release behavior of Cu/Ti film prepared via physical vapor deposition in vitro as potential biomaterials for cardiovascular devices

    Energy Technology Data Exchange (ETDEWEB)

    Liu Hengquan [Center of Research and Development, Lifetech Scientific (Shenzhen) Co., Ltd., Shenzhen 518057 (China); Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Zhang Deyuan, E-mail: zhangdeyuan@lifetechmed.com [Center of Research and Development, Lifetech Scientific (Shenzhen) Co., Ltd., Shenzhen 518057 (China); Shen Feng [Center of Research and Development, Lifetech Scientific (Shenzhen) Co., Ltd., Shenzhen 518057 (China); Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Zhang Gui [Center of Research and Development, Lifetech Scientific (Shenzhen) Co., Ltd., Shenzhen 518057 (China); Song Shenhua [Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China)

    2012-07-15

    Cu/Ti films of various Cu/Ti ratios were prepared on a TiNi alloy via vacuum arc plasma deposition. The phase composition, structure, and concentration of elements were investigated via X-ray diffraction and X-photoelectron energy spectrum. The hemolysis ratio and platelet adhesion of the different films were characterized to evaluate blood compatibility. The corrosion and ion release behavior were investigated via a typical immersion test and electrochemical method. The growth of endothelial cells (ECs) was investigated, and methylthiazolyte-trazolium method was employed to evaluate the effect of Cu{sup 2+}. The sophisticated films showed good compatibility. However, with increasing quality ratio of Cu/Ti, the hemolysis ratio increased, and some platelets started to break slightly. The Cu{sup 2+} release was gradually stabilized. The open circuit potential of the Cu/Ti film-modified samples was lower than that of the TiNi substrate. The polarization test result indicates that the passivation stability performance of Cu/Ti film samples is less than the TiNi substrate, and is favorable to Cu{sup 2+} release. The adhesion and proliferation of ECs would be inhibited with 10 wt.% Cu concentration of the film, and ECs would undergo apoptosis at >50 wt.% concentration. A Cu/Ti film with good compatibility and anti-endothelialization has potential applications for special cardiovascular devices.

  20. Epitaxial Cu{sub 2}ZnSnSe{sub 4} thin films and devices

    Energy Technology Data Exchange (ETDEWEB)

    Redinger, Alex [Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, 41, rue du Brill, L-4422 Belvaux (Luxembourg); Groiss, Heiko [Karlsruhe Institute of Technology, Laboratory for Electron Microscopy, Engesserstr. 7, D-76131 Karlsruhe (Germany); Sendler, Jan; Djemour, Rabie; Regesch, David [Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, 41, rue du Brill, L-4422 Belvaux (Luxembourg); Gerthsen, Dagmar [Karlsruhe Institute of Technology, Laboratory for Electron Microscopy, Engesserstr. 7, D-76131 Karlsruhe (Germany); Siebentritt, Susanne, E-mail: susanne.siebentritt@uni.lu [Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, 41, rue du Brill, L-4422 Belvaux (Luxembourg)

    2015-05-01

    Epitaxial Cu{sub 2}ZnSnSe{sub 4} (CZTSe) thin films have been grown via high temperature coevaporation on GaAs(001). Electron backscattering diffraction confirms epitaxy in a wide compositional range. Different secondary phases are present in the epitaxial layer. The main secondary phases are Cu{sub 2}SnSe{sub 3} and ZnSe which grow epitaxially on top of the CZTSe. Transmission electron microscopy measurements show that the epitaxial CZTSe grows predominantly parallel to the c-direction. Epitaxial CZTSe solar cells with a maximum power conversion efficiency of 2.1%, an open-circuit voltage of 223 mV and a current density of 16 mA/cm{sup 2} are presented. - Highlights: • Epitaxial Cu{sub 2}ZnSnSe{sub 4} has been grown on GaAs(001). • Material includes epitaxial Cu{sub 2}SnSe{sub 3} and ZnSe secondary phases. • TEM investigations show that the orientation is mainly parallel to the c-direction. • Epitaxial solar cells have been fabricated.

  1. Osmium Complexes Useful in the Preparation of Metal Thin Film and Highly Efficient Electroluminescent Devices

    Institute of Scientific and Technical Information of China (English)

    Yun Chi

    2004-01-01

    Treatment of β-diketone ligand, such as hfacH (hexafluoroacetylacetone), with Os3(CO)12 in a stainless steel autoclave at elevated temperature afforded the corresponding mononuclear osmium complex [Os(CO)3(hfac)(tfa)] (1) in good yield. This complex is highly volatile and displays moderate stability at the higher temperatures; thus, it can be utilized for depositing metal thin-film material with overall quality comparable or better than those deposited using the commercially available chemical reagents. Moreover, combination of Os3(CO)12 with another class of chelate ligand such as 3-trifluoromethyl-5-(2-pyridyl) pyrazole (ppz)H gave formation of the Os(H) dicarbonyl complex [Os(CO)2(ppz)2] (2). This osmium complex shows blue phosphorescence at room temperature, which is characteristic for the 3ππ* emission with vibronic progressions at 430,457 and 480 nm. The remarkable photophysical properties were rationalized by a combination of π electron accepting CO ligand, relative ppz orientation and heavy-atom enhanced spin-orbit coupling effects. Related chemical transformations that afforded other useful luminescent Os complexes are presented.

  2. Thickness controlled sol-gel silica films for plasmonic bio-sensing devices

    Science.gov (United States)

    Figus, Cristiana; Quochi, Francesco; Artizzu, Flavia; Saba, Michele; Marongiu, Daniela; Floris, Francesco; Marabelli, Franco; Patrini, Maddalena; Fornasari, Lucia; Pellacani, Paola; Valsesia, Andrea; Mura, Andrea; Bongiovanni, Giovanni

    2014-10-01

    Plasmonics has recently received considerable interest due to its potentiality in many fields as well as in nanobio-technology applications. In this regard, various strategies are required for modifying the surfaces of plasmonic nanostructures and to control their optical properties in view of interesting application such as bio-sensing, We report a simple method for depositing silica layers of controlled thickness on planar plasmonic structures. Tetraethoxysilane (TEOS) was used as silica precursor. The control of the silica layer thickness was obtained by optimizing the sol-gel method and dip-coating technique, in particular by properly tuning different parameters such as pH, solvent concentration, and withdrawal speed. The resulting films were characterized via atomic force microscopy (AFM), Fourier-transform (FT) spectroscopy, and spectroscopic ellipsometry (SE). Furthermore, by performing the analysis of surface plasmon resonances before and after the coating of the nanostructures, it was observed that the position of the resonance structures could be properly shifted by finely controlling the silica layer thickness. The effect of silica coating was assessed also in view of sensing applications, due to important advantages, such as surface protection of the plasmonic structure.

  3. Thickness controlled sol-gel silica films for plasmonic bio-sensing devices

    Energy Technology Data Exchange (ETDEWEB)

    Figus, Cristiana, E-mail: cristiana.figus@dsf.unica.it; Quochi, Francesco, E-mail: cristiana.figus@dsf.unica.it; Artizzu, Flavia, E-mail: cristiana.figus@dsf.unica.it; Saba, Michele, E-mail: cristiana.figus@dsf.unica.it; Marongiu, Daniela, E-mail: cristiana.figus@dsf.unica.it; Mura, Andrea; Bongiovanni, Giovanni [Dipartimento di Fisica - University of Cagliari, S.P. Km 0.7, I-09042 Monserrato (Canada) (Italy); Floris, Francesco; Marabelli, Franco; Patrini, Maddalena; Fornasari, Lucia [Dipartimento di Fisica - University of Pavia, Via Agostino Bassi 6, I-27100 Pavia (PV) (Italy); Pellacani, Paola; Valsesia, Andrea [Plasmore S.r.l. -Via Grazia Deledda 4, I-21020 Ranco (Vatican City State, Holy See) (Italy)

    2014-10-21

    Plasmonics has recently received considerable interest due to its potentiality in many fields as well as in nanobio-technology applications. In this regard, various strategies are required for modifying the surfaces of plasmonic nanostructures and to control their optical properties in view of interesting application such as bio-sensing, We report a simple method for depositing silica layers of controlled thickness on planar plasmonic structures. Tetraethoxysilane (TEOS) was used as silica precursor. The control of the silica layer thickness was obtained by optimizing the sol-gel method and dip-coating technique, in particular by properly tuning different parameters such as pH, solvent concentration, and withdrawal speed. The resulting films were characterized via atomic force microscopy (AFM), Fourier-transform (FT) spectroscopy, and spectroscopic ellipsometry (SE). Furthermore, by performing the analysis of surface plasmon resonances before and after the coating of the nanostructures, it was observed that the position of the resonance structures could be properly shifted by finely controlling the silica layer thickness. The effect of silica coating was assessed also in view of sensing applications, due to important advantages, such as surface protection of the plasmonic structure.

  4. Estimation of intake of bisphenol-A-diglycidyl-ether (BADGE) from canned fish consumption in Europe and migration survey.

    Science.gov (United States)

    Simoneau, C; Theobald, A; Wiltschko, D; Anklam, E

    1999-11-01

    The exposure to bisphenol-A-diglycidyl-ether (BADGE) from canned fish in oil was assessed from consumption data collected for each Member State of the European Union and Switzerland, and migration data from a European survey on 382 samples. Trade figures were used when no consumption data were available. The average consumption of canned fish in Europe was 2.3 kg per person per year, with values ranging from 0.2 kg per person per year in the United Kingdom to 5.1 kg per person per year in Denmark. The exposure to BADGE was calculated as microgram per person per day. The data indicated that exposure to BADGE was in the range below 4 mg per person per year, i.e. 9 micrograms per person per day, hence a fairly low exposure in part due to the fact that canned fish is a relatively minor dietary item. An approximation assuming the general figure of a 60 kg adult, would thus be 0.15 microgram/kg body weight per day. This is a fairly limited exposure considering the provisional limit in food had been set a 1 mg/kg and assumed 1 kg of food ingested. In countries for which increased exposure was found, the reason was mainly caused by one individual sample exhibiting a high concentration rather than a larger number of samples with mildly elevated concentrations.

  5. RFID and Memory Devices Fabricated Integrally on Substrates

    Science.gov (United States)

    Schramm, Harry F.

    2004-01-01

    Electronic identification devices containing radio-frequency identification (RFID) circuits and antennas would be fabricated integrally with the objects to be identified, according to a proposal. That is to say, the objects to be identified would serve as substrates for the deposition and patterning of the materials of the devices used to identify them, and each identification device would be bonded to the identified object at the molecular level. Vacuum arc vapor deposition (VAVD) is the NASA derived process for depositing layers of material on the substrate. This proposal stands in contrast to the current practice of fabricating RFID and/or memory devices as wafer-based, self-contained integrated-circuit chips that are subsequently embedded in or attached to plastic cards to make smart account-information cards and identification badges. If one relies on such a chip to store data on the history of an object to be tracked and the chip falls off or out of the object, then one loses both the historical data and the means to track the object and verify its identity electronically. Also, in contrast is the manufacturing philosophy in use today to make many memory devices. Today s methods involve many subtractive processes such as etching. This proposal only uses additive methods, building RFID and memory devices from the substrate up in thin layers. VAVD is capable of spraying silicon, copper, and other materials commonly used in electronic devices. The VAVD process sprays most metals and some ceramics. The material being sprayed has a very strong bond with the substrate, whether that substrate is metal, ceramic, or even wood, rock, glass, PVC, or paper. An object to be tagged with an identification device according to the proposal must be compatible with a vacuum deposition process. Temperature is seldom an issue as the substrate rarely reaches 150 F (66 C) during the deposition process. A portion of the surface of the object would be designated as a substrate for

  6. Perovskite single crystals and thin films for optoelectronic devices (Conference Presentation)

    Science.gov (United States)

    Li, Gang; Han, Qifeng; Yang, Yang; Bae, Sang-Hoon; Sun, Pengyu

    2016-09-01

    Hybrid organolead trihalide perovskite (OTP) solar cells have developed as a promising candidate in photovoltaics due to their excellent properties including a direct bandgap, strong absorption coefficient, long carrier lifetime, and high mobility. Most recently, formamidinium (NH2CH=NH2+ or FA) lead iodide (FAPbI3) has attracted significant attention due to several advantages: (1) the larger organic FA cation can replace the MA cation and form a more symmetric crystal structure, (2) the smaller bandgap of FAPbI3 allows for near infrared (NIR) absorption, and (3) FAPbI3 has an elevated decomposition temperature and thus potential to improve stability. Single crystals provide an excellent model system to study the intrinsic electrical and optical properties of these materials due to their high purity, which is particularly important to understand the limits of these materials. In this work, we report the growth of large ( 5 millimeter size) single crystal FAPbI3 using a novel liquid based crystallization method. The single crystal FAPbI3 demonstrated a δ-phase to α-phase transition with a color change from yellow to black when heated to 185°C within approximately two minutes. The crystal structures of the two phases were identified and the PL emission peak of the α-phase FAPbI3 (820 nm) shows clear red-shift compared to the FAPbI3 thin film (805 nm). The FAPbI3 single crystal shows a long carrier lifetime of 484 ns, a high carrier mobility of 4.4 cm2·V-1·s-1, and even more interestingly a conductivity of 1.1 × 10-7(ohm·cm)-1, which is approximately one order of magnitude higher than that of the MAPbI3 single crystal. Finally, high performance photoconductivity type photodetectors were successfully demonstrated using the single crystal FAPbI3.

  7. Using volatile additives to alter the morphology and performance of active layers in thin-film molecular photovoltaic devices incorporating bulk heterojunctions.

    Science.gov (United States)

    Dang, Minh Trung; Wuest, James D

    2013-12-07

    Thin-film photovoltaic devices composed of polymers or small molecules have an exciting future as sources of renewable energy because they can be made in large sizes on flexible surfaces by inexpensive techniques of fabrication. Significant progress in developing new molecular photovoltaic materials and device architectures has been achieved in the last decade. The identity of molecular components in active layers and their individual optoelectronic properties obviously help determine the properties of devices; in addition, however, the behavior of devices depends critically on the nature of the local organization of the components. Recent studies have shown that the morphology of active layers can be tuned by adjusting various parameters, including the solvent used to cast the layer, thermal annealing, and special processing additives. In this review, we summarize the effect of volatile additives on the nanoscale morphology of molecular blends, and we show how these effects can improve the performance of devices. Although we focus on the behavior of mixtures of the type used in current molecular thin-film photovoltaic devices, the subject of our review will interest researchers in all areas of science and technology requiring materials in which separate phases must form intimate long-lived intermixtures with defined structures.

  8. A novel approach for correlating capacitance data with performance during thin-film device stress studies

    Science.gov (United States)

    Graham, Rebekah L.; Clark, Laura A.; Albin, David S.

    2011-09-01

    A new data mining algorithm was developed to identify the strongest correlations between capacitance data (measured between -1.5 V and +0.49 V) and first- and second-level performance metrics (efficiency [η%], open-circuit voltage [VOC], short-circuit current density [JSC], and fill-factor [FF]) during the stress testing of voltage-stabilized CdS/CdTe devices. When considering only correlations between first- and second-level metrics, 96.5% of the observed variation in η% was attributed to FF. The overall decrease in VOC after 1,000 hours of open-circuit, light-soak stress at 60°C was about -1.5%. As determined by our algorithm, the most consistent correlation existing between FF and third-level metric capacitance data at all stages during stress testing was between FF and the apparent CdTe acceptor density (Na) calculated at a voltage of +0.49 V during forward voltage scans. Since the contribution of back-contact capacitance to total capacitance increases with increasing positive voltage, this result suggests that FF degradation is associated with decreases in Na near the CdTe/back contact interface. Also of interest, it appears that capacitance data at these higher voltages appears to more accurately fit the one-sided abrupt junction model.

  9. Novel Approach for Correlating Capacitance Data with Performance During Thin-Film Device Stress Studies: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R. L.; Albin, D. S.; Clark, L. A.

    2011-08-01

    A new data mining algorithm was developed to identify the strongest correlations between capacitance data (measured between -1.5 V and +0.49 V) and 1st and 2nd level performance metrics (efficiency, open-circuit voltage (VOC), short-circuit current density (JSC), and fill-factor (FF)) during the stress testing of voltage-stabilized CdS/CdTe devices. When considering only correlations between 1st and 2nd level metrics, 96.5% of the observed variation in efficiency was attributed to FF. The overall decrease in VOC after 1000 hours of open-circuit, light-soak stress at 60 degrees C was about 1.5%. As determined by our algorithm, the most consistent correlation existing between FF and 3rd level metric capacitance data at all stages during stress testing was between FF and the apparent CdTe acceptor density (Na) calculated at a voltage of +0.49 V during forward voltage scans. Since the contribution of back contact capacitance to total capacitance increases with increasing positive voltage, this result suggests that FF degradation is associated with decreases in Na near the CdTe/back contact interface. Also of interest, it appears that capacitance data at these higher voltages appears to more accurately fit the one-sided abrupt junction model.

  10. Atomic layer epitaxy of group 4 materials: Surface processes, thin films, devices and their characterization

    Science.gov (United States)

    Davis, Robert F.

    1994-06-01

    The viability of Si2Cl6, C2H2 and C2H4 as precursors for chemically self-limiting ALE of SiC has been investigated via XPS and LEED. Si2Cl6 readily adsorbs in a self-limiting manner on a Si(100) surface; however, neither hydrocarbon will adsorb or react with a Cl-terminated Si surface to 475 deg C. Conversely, partial chlorination of Si(100) saturated with C2H2 and C2H4 does occur and implies that Si2Cl6 will adsorb/react with a hydrocarbon terminated surface. Layer-by-layer growth of Beta-SiC on Si(100) or 6H-SiC has been achieved with a carrier concentration of approx. 10(exp 17)/cu cm. P-type doping with Al has allowed the achievement of hole concentrations of 4 x 10(exp 18) - 2 10(exp 20)/cu cm. Efforts to produce an HBT using Beta-SiC emitters is described. Ni3Si has been employed for the deposition of diamond because of the close lattice match. Under the same growth conditions, diamond particles were obtained on the Ni3Si, but only diamond-like C and graphite on pure Ni substrates. Evidence of oriented particles was observed. REED and TEM of cerium oxide films grown on Si(111) substrates has revealed the formation of a dual amorphous layer of CeOx and SiO2 at the Si interface followed by a layer of CeO2. Post annealing in dry oxygen caused the CeOx layer to disappear and the SiO2 layer to thicken. D(sub it) = 6 x 10(exp 11)/sq cm and Q sub f = 5 x 10(exp 11)/sq cm. The structure exhibits a high capacitance due to the large dielectric constant of CeO2 and has electrical properties comparable with those of other reported gate insulators on Si.

  11. Enhanced quality thin film Cu(In,Ga)Se.sub.2 for semiconductor device applications by vapor-phase recrystallization

    Science.gov (United States)

    Tuttle, John R.; Contreras, Miguel A.; Noufi, Rommel; Albin, David S.

    1994-01-01

    Enhanced quality thin films of Cu.sub.w (In,Ga.sub.y)Se.sub.z for semiconductor device applications are fabricated by initially forming a Cu-rich, phase-separated compound mixture comprising Cu(In,Ga):Cu.sub.x Se on a substrate to form a large-grain precursor and then converting the excess Cu.sub.x Se to Cu(In,Ga)Se.sub.2 by exposing it to an activity of In and/or Ga, either in vapor In and/or Ga form or in solid (In,Ga).sub.y Se.sub.z. Alternatively, the conversion can be made by sequential deposition of In and/or Ga and Se onto the phase-separated precursor. The conversion process is preferably performed in the temperature range of about 300.degree.-600.degree. C., where the Cu(In,Ga)Se.sub.2 remains solid, while the excess Cu.sub.x Se is in a liquid flux. The characteristic of the resulting Cu.sub.w (In,Ga).sub.y Se.sub.z can be controlled by the temperature. Higher temperatures, such as 500.degree.-600.degree. C., result in a nearly stoichiometric Cu(In,Ga)Se.sub.2, whereas lower temperatures, such as 300.degree.-400.degree. C., result in a more Cu-poor compound, such as the Cu.sub.z (In,Ga).sub.4 Se.sub.7 phase.

  12. Enhanced quality thin film Cu(In,Ga)Se[sub 2] for semiconductor device applications by vapor-phase recrystallization

    Science.gov (United States)

    Tuttle, J.R.; Contreras, M.A.; Noufi, R.; Albin, D.S.

    1994-10-18

    Enhanced quality thin films of Cu[sub w](In,Ga[sub y])Se[sub z] for semiconductor device applications are fabricated by initially forming a Cu-rich, phase-separated compound mixture comprising Cu(In,Ga):Cu[sub x]Se on a substrate to form a large-grain precursor and then converting the excess Cu[sub x]Se to Cu(In,Ga)Se[sub 2] by exposing it to an activity of In and/or Ga, either in vapor In and/or Ga form or in solid (In,Ga)[sub y]Se[sub z]. Alternatively, the conversion can be made by sequential deposition of In and/or Ga and Se onto the phase-separated precursor. The conversion process is preferably performed in the temperature range of about 300--600 C, where the Cu(In,Ga)Se[sub 2] remains solid, while the excess Cu[sub x]Se is in a liquid flux. The characteristic of the resulting Cu[sub w](In,Ga)[sub y]Se[sub z] can be controlled by the temperature. Higher temperatures, such as 500--600 C, result in a nearly stoichiometric Cu(In,Ga)Se[sub 2], whereas lower temperatures, such as 300--400 C, result in a more Cu-poor compound, such as the Cu[sub z](In,Ga)[sub 4]Se[sub 7] phase. 7 figs.

  13. Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V.

    Science.gov (United States)

    Basiricò, Laura; Ciavatti, Andrea; Cramer, Tobias; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2016-10-06

    The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 10(4) and 77,000 nC mGy(-1) cm(-3), respectively.

  14. Structural and optical properties of silicon rich oxide films in graded-stoichiometric multilayers for optoelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Palacios-Huerta, L.; Aceves-Mijares, M. [Electronics Department, INAOE, Apdo. 51, Puebla, Pue. 72000, México (Mexico); Cabañas-Tay, S. A.; Cardona-Castro, M. A.; Morales-Sánchez, A., E-mail: alfredo.morales@cimav.edu.mx [Centro de Investigación en Materiales Avanzados S.C., Unidad Monterrey-PIIT, Apodaca, NL 66628, México (Mexico); Domínguez-Horna, C. [Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Bellaterra 08193, Barcelona (Spain)

    2016-07-18

    Silicon nanocrystals (Si-ncs) are excellent candidates for the development of optoelectronic devices. Nevertheless, different strategies are still necessary to enhance their photo and electroluminescent properties by controlling their structural and compositional properties. In this work, the effect of the stoichiometry and structure on the optical properties of silicon rich oxide (SRO) films in a multilayered (ML) structure is studied. SRO MLs with silicon excess gradually increased towards the top and bottom and towards the center of the ML produced through the variation of the stoichiometry in each SRO layer were fabricated and confirmed by X-ray photoelectron spectroscopy. Si-ncs with three main sizes were observed by a transmission electron microscope, in agreement with the stoichiometric profile of each SRO layer. The presence of the three sized Si-ncs and some oxygen related defects enhances intense violet/blue and red photoluminescence (PL) bands. The SRO MLs were super-enriched with additional excess silicon by Si{sup +} implantation, which enhanced the PL intensity. Oxygen-related defects and small Si-ncs (<2 nm) are mostly generated during ion implantation enhancing the violet/blue band to become comparable to the red band. The structural, compositional, and luminescent characteristics of the multilayers are the result of the contribution of the individual characteristics of each layer.

  15. Electrochromic devices based on surface-modified nanocrystalline TiO{sub 2} thin-film electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Campus, F.; Bonhote, P.; Graetzel, M. [Institut de Chimie Physique, Ecole Polytechnique Federale, CH-1015 Lausanne (Switzerland); Heinen, S.; Walder, L. [Institut fuer Chemie, Universitaet Osnabrueck, Barbarastr 7, D-49069 Osnabrueck (Germany)

    1998-12-30

    Nanocrystalline TiO{sub 2} thin film electrodes on conductive glass were modified with monolayers of different electrochromic compounds (mono-, di- and trimeric N,N`-dialkyl- or-diphenyl-4,4`-bipyridinium salts) equipped with TiO{sub 2} anchoring groups (An=benzoate, salicylate, phosphonate). The synthesis of these compounds is reported. Different approaches have been studied to increase the surface concentration {Gamma}{sub CS} of electrochemically active coloring centers (CS) on TiO{sub 2}. The electrodes were checked coulometrically and spectroelectrochemically under potentiostatic conditions in MeCN/TEAP. {Gamma}{sub CS} of mono- and oligomeric viologens was shown to depend on the ratio (CS/An) of CS to anchoring groups (An). A cone-shaped trimeric arborol-type viologen was prepared with the intention to fill out the space above the convex surface of the nanoparticles particularly well. Preliminary results of a new type of TiO{sub 2} solid-phase supported synthesis of the viologens is reported. Electrochromic devices including filters and displays have been prepared. The filter devices (12-100 cm{sup 2}) consist generally of OTE/TiO{sub 2}-poly-viologen/glutaronitrile-LiN(SO{sub 2}CF{sub 3}){sub 2}+spacer/Prussian Blue/OTE and exhibit optical density changes up to 2 (transparent to blue or yellowish to green and red-brown (at higher potential)) at switching times in the range of 1-3 s. Even higher optical density changes (at slower switching times) were achieved with systems such as OTE/TiO{sub 2}-poly-viologen/glutaronitrile-LiN(SO{sub 2}CF{sub 3}){sub 2}+spacer/Prussian Blue-TiO{sub 2}/OTE. The display devices prepared include reflective displays with two to four separately addressable segments ((OTE/TiO{sub 2} (both structured)-oligo-viologen/microcrystalline rutile (reflective layer)/molten salt+spacer/Zn) or (OTE/TiO{sub 2} (both structured)-oligo-viologen/microcrystalline rutile (reflective layer)/glutaronitrile-LiN(SO{sub 2}CF{sub 3}){sub 2}+spacer

  16. Optimization of Processing and Modeling Issues for Thin-Film Solar Cell Devices; Annual Report, 3 February 1997-2 February 1998

    Energy Technology Data Exchange (ETDEWEB)

    Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Hegedus, S. S.; McCandless, B. E. (IEC, University of Delaware)

    1998-12-08

    This report describes results achieved during phase I of a four-phase subcontract to develop and understand thin-film solar cell technology associated with CuInSe2 and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE long-range efficiency, reliability, and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for developing viable commercial processes and to improve module performance. The generic research issues addressed are: (1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; (2) device characterization relating the device performance to materials properties and process conditions; (3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; (4) development of improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to illumination, temperature, and ambient and with respect to device structure and module encapsulation.

  17. Homo-junction ferroelectric field-effect-transistor memory device using solution-processed lithium-doped zinc oxide thin films

    KAUST Repository

    Nayak, Pradipta K.

    2012-06-22

    High performance homo-junction field-effect transistor memory devices were prepared using solution processed transparent lithium-doped zinc oxide thin films for both the ferroelectric and semiconducting active layers. A highest field-effect mobility of 8.7 cm2/Vs was obtained along with an Ion/Ioff ratio of 106. The ferroelectric thin filmtransistors showed a low sub-threshold swing value of 0.19 V/dec and a significantly reduced device operating voltage (±4 V) compared to the reported hetero-junction ferroelectrictransistors, which is very promising for low-power non-volatile memory applications.

  18. All-Solid-Thin Film Electrochromic Devices Consisting of Layers ITO / NiO / ZrO2 / WO3 / ITO

    Directory of Open Access Journals (Sweden)

    K.J. Patel

    2013-05-01

    Full Text Available We have prepared an all-solid-thin film electrochromic device (ECD, consisting of layers ITO / NiO / ZrO2 / WO3 / ITO using the PVD method. The WO3 is used as an electrochromic layer, NiO as an ion-storage layer, and ZrO2 as a solid electrolyte layer in the all-solid-thin film ECD. The optical transmittance varied between 3-59 %. The device shows the coloration and bleaching time of 120 s and 2 s, respectively, with a good memory effect and desirable cycle-life.

  19. Contribution of the cashew gum (Anacardium occidentale L.) for development of layer-by-layer films with potential application in nanobiomedical devices.

    Science.gov (United States)

    Araújo, I M S; Zampa, M F; Moura, J B; dos Santos, J R; Eaton, P; Zucolotto, V; Veras, L M C; de Paula, R C M; Feitosa, J P A; Leite, J R S A; Eiras, C

    2012-08-01

    The search for bioactive molecules to be employed as recognition elements in biosensors has stimulated researchers to pore over the rich Brazilian biodiversity. In this sense, we introduce the use of natural cashew gum (Anacardium occidentale L.) as an active biomaterial to be used in the form of layer-by-layer films, in conjunction with phthalocyanines, which were tested as electrochemical sensors for dopamine detection. We investigated the effects of chemical composition of cashew gum from two different regions of Brazil (Piauí and Ceará states) on the physico-chemical characteristics of these nanostructures. The morphology of the nanostructures containing cashew gum was studied by atomic force microscopy which indicates that smooth films punctuated by globular features were formed that showed low roughness values. The results indicate that, independent of the origin, cashew gum stands out as an excellent film forming material with potential application in nanobiomedical devices as electrochemical sensors.

  20. Preparation and properties of all-solid-state inorganic thin film glass/ITO/WO3/LiNbO3/NiOx/ITO electrochromic device

    Science.gov (United States)

    Wu, Zhonghou; Diao, Xungang; Dong, Guobo

    2016-01-01

    The all-thin-film inorganic electrochromic device (ECD) with LiNbO3 as the ion conductor layer was prepared. The ECD was fabricated monolithically in a same vacuum chamber layer by layer using DC reactive sputtering for WO3, NiOx and ITO, and radio frequency (RF) sputtering for LiNbO3. The properties and performance of WO3 thin film and the ECD were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible spectrometry. WO3 thin film has more than 60% optical modulation with porous amorphous structure. The visible transmittance modulation of the ECD is more than 65%, and the response time of coloring and bleaching are 45 s and 25 s, respectively.

  1. Pulsed-laser-deposited AlN films for high-temperature SiC MIS devices[Metal-Insulator-Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Vispute, R.D.; Patel, A.; Baynes, K. [and others

    2000-07-01

    The authors report on the fabrication of device-quality AlN heterostructures grown on SiC for high-temperature electronic devices. The AlN films were grown by pulsed laser deposition (PLD) at substrate temperatures ranging from 25 C (room temperature) to 1000 C. The as-grown films were investigated using x-ray diffraction, Rutherford backscattering spectroscopy, ion channeling, atomic force microscopy, and transmission electron microscopy. The AlN films grown above 700 C were highly c-axis oriented with rocking curve FWHM of 5 to 6 arc-min. The ion channeling minimum yields near the surface region for the AlN films were {approximately}2 to 4%, indicating their high degree of crystallinity. TEM studies indicated that AlN films were epitaxial and single crystalline in nature with a large number of stacking faults as a result of lattice mismatch and growth induced defects. The surface roughness for the films was about 0.5 nm, which is close to the unit cell height of the AlN. Epitaxial TiN ohmic contacts were also developed on SiC, GaN, and AlN by in-situ PLD. Epitaxial TiN/AlN/SiC MIS capacitors with gate areas of 4 {sup {minus}} 10{sup {minus}4} cm{sup 2} were fabricated, and high-temperature current-voltage (I-V) characteristics were studied up to 450 C. The authors have measured leakage current densities of low 10{sup {minus}8} A/cm{sup 2} at room temperature, and have mid 10{sup {minus}3} A/cm{sup 2} at 450 C under a field of 2 MV/cm.

  2. Titanium dioxide thin films deposited by pulsed laser deposition and integration in radio frequency devices: Study of structure, optical and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Orlianges, Jean-Christophe, E-mail: jean-christophe.orlianges@unilim.fr [SPCTS, UMR 7315, Universite de Limoges/CNRS, 12 rue Atlantis, 87068 Limoges Cedex (France); Crunteanu, Aurelian; Pothier, Arnaud [XLIM, UMR 7252, Universite de Limoges/CNRS, 123, avenue Albert Thomas, 87060 Limoges Cedex (France); Merle-Mejean, Therese [SPCTS, UMR 7315, Universite de Limoges/CNRS, 12 rue Atlantis, 87068 Limoges Cedex (France); Blondy, Pierre [XLIM, UMR 7252, Universite de Limoges/CNRS, 123, avenue Albert Thomas, 87060 Limoges Cedex (France); Champeaux, Corinne [SPCTS, UMR 7315, Universite de Limoges/CNRS, 12 rue Atlantis, 87068 Limoges Cedex (France)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer We have grown TiO{sub 2} thin films by PLD on c-sapphire substrate with pre-patterned out-plane capacitor structures. Black-Right-Pointing-Pointer Raman and XRD analyses indicate an evolution from 'amorphous' to anatase and rutile phase. Black-Right-Pointing-Pointer Thin films optical properties are investigated using spectroscopic ellipsometry and transmission measurements. Black-Right-Pointing-Pointer Permittivity measurements reveal high dielectric constant {epsilon}{sub r} = 120 of 600 Degree-Sign C-grown TiO{sub 2} thin films. - Abstract: Titanium dioxide presents a wide range of technological application possibilities due to its dielectric, electrochemical, photocatalytic and optical properties. The three TiO{sub 2} allotropic forms: anatase, rutile and brookite are also interesting, since they exhibit different properties, stabilities and growth modes. For instance, rutile has a high dielectric permittivity, of particular interest for the integration as dielectric in components such as microelectromechanical systems (MEMS) for radio frequency (RF) devices. In this study, titanium dioxide thin films are deposited by pulsed laser deposition. Characterizations by Raman spectroscopy and X-ray diffraction show the evolution of the structural properties. Thin films optical properties are investigated using spectroscopic ellipsometry and transmission measurements from UV to IR range. Co-planar waveguide (CPW) devices are fabricated based on these films. Their performances are measured in the RF domain and compared to simulation, leading to relative permittivity values in the range 30-120, showing the potentialities of the deposited material for capacitive switches applications.

  3. High-performance electrochromic device based on nanocellulose/polyaniline and nanocellulose/poly(3,4-ethylenedioxythiophene) composite thin films

    Science.gov (United States)

    Zhang, Sihang; Fu, Runfang; Du, Zoufei; Jiang, Mengjin; Zhou, Mi; Gu, Yingchun; Chen, Sheng

    2017-07-01

    With the development of nanotechnology, nanocomposite materials based on renewable resources are the focus of this research. Nanocellulose was prepared using sulfuric acid to swell cotton pulp, following with extensive ultrasonication. Nanocellulose/polyaniline (NC/PANI) and nanocellulose/poly(3,4-ethylenedioxythiophene) (NC/PEDOT) nanocomposites with core/shell structure were manufactured by in situ polymerization. The film-forming properties and electrochromic properties of PANI and PEDOT were significantly improved using the nanocellulose as matrix. NC/PANI and NC/PEDOT composite films were studied in single and dual electrochromic devices (ECDs). A viscous gel electrolyte (GE) was used in ECDs. The architectural design of single and dual device was ITO/NC-PANI/GE/ITO or ITO/NC-PEDOT/GE/ITO and ITO/NC-PANI/GE/NC-PEDOT/ITO, respectively. The dual ECD based on NC/PANI and NC/PEDOT composite films exhibited a higher color contrast (30.3%), shortest response time (1.5 s for bleaching and 1.9 s for coloring), largest coloration efficiency (241.6 C/cm2), and best cycling stability (over 150 cycles) compared with the single devices.

  4. A backing device based on an embedded stiffener and retractable insertion tool for thin-film cochlear arrays

    Science.gov (United States)

    Tewari, Radheshyam

    Intracochlear trauma from surgical insertion of bulky electrode arrays and inadequate pitch perception are areas of concern with current hand-assembled commercial cochlear implants. Parylene thin-film arrays with higher electrode densities and lower profiles are a potential solution, but lack rigidity and hence depend on manually fabricated permanently attached polyethylene terephthalate (PET) tubing based bulky backing devices. As a solution, we investigated a new backing device with two sub-systems. The first sub-system is a thin poly(lactic acid) (PLA) stiffener that will be embedded in the parylene array. The second sub-system is an attaching and detaching mechanism, utilizing a poly(N-vinylpyrrolidone)-block-poly(d,l-lactide) (PVP-b-PDLLA) copolymer-based biodegradable and water soluble adhesive, that will help to retract the PET insertion tool after implantation. As a proof-of-concept of sub-system one, a microfabrication process for patterning PLA stiffeners embedded in parylene has been developed. Conventional hot-embossing, mechanical micromachining, and standard cleanroom processes were integrated for patterning fully released and discrete stiffeners coated with parylene. The released embedded stiffeners were thermoformed to demonstrate that imparting perimodiolar shapes to stiffener-embedded arrays will be possible. The developed process when integrated with the array fabrication process will allow fabrication of stiffener-embedded arrays in a single process. As a proof-of-concept of sub-system two, the feasibility of the attaching and detaching mechanism was demonstrated by adhering 1x and 1.5x scale PET tube-based insertion tools and PLA stiffeners embedded in parylene using the copolymer adhesive. The attached devices survived qualitative adhesion tests, thermoforming, and flexing. The viability of the detaching mechanism was tested by aging the assemblies in-vitro in phosphate buffer solution. The average detachment times, 2.6 minutes and 10 minutes

  5. Ferroelectric ultrathin perovskite films

    Science.gov (United States)

    Rappe, Andrew M; Kolpak, Alexie Michelle

    2013-12-10

    Disclosed herein are perovskite ferroelectric thin-film. Also disclosed are methods of controlling the properties of ferroelectric thin films. These films can be used in a variety materials and devices, such as catalysts and storage media, respectively.

  6. Electrochemistry of poly(3,4-ethylenedioxythiophene)-polyaniline/ Prussian blue electrochromic devices containing an ionic liquid based gel electrolyte film.

    Science.gov (United States)

    Deepa, Melepurath; Awadhia, Arvind; Bhandari, Shweta

    2009-07-21

    Electrochromic devices based on poly(3,4-ethylenedioxythiophene) (PEDOT) as the cathodic coloring electrode and polyaniline (PANI) or Prussian blue (PB) as the counter electrode containing a highly conductive, self-supporting, distensible and transparent polymer-gel electrolyte film encapsulating an ionic liquid, 1-butyl-1-methylpyrrolidiniumbis-(trifluoromethylsulfonyl)imide, have been fabricated. Polarization, charge transfer and diffusion processes control the electrochemistry of the functional electrodes during coloration and bleaching and these phenomena differ when PEDOT and PANI/PB were employed alternately as working electrodes. While the electrochemical impedance response shows good similitude for PEDOT and PANI electrodes, the responses of PEDOT and PB were significantly different in the PEDOT-PB device, especially during reduction of PB, wherein the overall amplitude of the impedance response is enormous. Large values of the coloration efficiency maxima of 281 cm2 C(-1) (lambda = 583 nm) and 274 cm2 C(-1) (lambda = 602 nm), achieved at -1.0 and -1.5 V for the PEDOT PANI and PEDOT-PB devices have been correlated to the particularly low magnitude of charge transfer resistance and high polarization capacitance operative at the PEDOT ionic liquid based electrolyte interface at these dc potentials, thus allowing facile ion-transport and consequently resulting in enhanced absorption modulation. Moderately fast switching kinetics and the ability of these devices to sustain about 2500 cycles of clear-to-dark and dark-to-clear without incurring major losses in the optical contrast, along with the ease of construction of these cells in terms of high scalability and reproducibility of the synthetic procedure for fabrication of the electrochromic films and the ionic liquid based gel electrolyte film, are indicators of the promise these devices hold for practical applications like electrochromic windows and displays.

  7. Recent progress in thin-film-silicon photovoltaic devices at CIEMAT; Recientes progresos en la tecnologia de dispositivos fotovoltaicos de silicio en lamina delgada en el CIEMAT

    Energy Technology Data Exchange (ETDEWEB)

    Gandia, J. J.; Carabe, J.

    2011-07-01

    Solar photovoltaic energy has evolved in the last 50 years on the basis of the co-existence of two fundamental technological paths: that of wafer-based silicon, dominating the market, and that of thin films, representing an important part of the options for the future of this energy-conversion field. More recently new concepts have gained significance, such as concentration photovoltaic (CPV), dye-sensitised solar cells (DSSC), organic cells, silicon-heterojunction (SHJ) cells and thin-crystalline silicon devices among others. over 90% of all these PV technologies are based on the use of either of the forms of the most abundant element of the earth crust: silicon. CIEMAT, being aware of the relevant role renewable energies and post-vocalic in particular must play in dinging solutions to the energy and environmental problem, has several action lines within this discipline. Among them is the one developed at the laboratory for Deposited-silicon Devices (DSD), entirely devoted to acquiring by own means the technology required for the fabrication of thin-film-silicon-based PV devices in order to be in conditions to give a maximum support to the Spanish industry in this field. Within the context of the historic evolution of PV technology in the world, this paper describes the progress of the DSD lab in the last years, according to a plan aimed at developing technology of the maximum strategic value. such a working scheme, supported by valuable collaborations, has led the group to a reference position in the areas of thin-film-silicon p-i-n devices on glass, silicon-heterojunction cells and p-i-n devices on flexible substrates. (Author) 5 refs.

  8. Influence of samaria doping on the resistance of ceria thin films and its implications to the planar oxygen sensing devices

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Shilpi; Kuchibhatla, Satyanarayana V N T; Engelhard, Mark H.; Shutthanandan, V.; Nachimuthu, Ponnusamy; Jiang, Weilin; Saraf, Laxmikant V.; Thevuthasan, Suntharampillai; Prasad, Shalini

    2009-05-27

    In order to evaluate and analyze the effect of samarium (Sm) doping on the resistance of cerium oxide, we have grown highly oriented samaria doped ceria (SDC) thin films on sapphire, Al2O3 (0001) substrates by using oxygen plasma-assisted molecular beam epitaxy (OPA-MBE). The film growth was monitored using reflection high-energy electron diffraction (RHEED) which shows two-dimensional growth throughout the deposition. Following growth, the thin films were characterized by X-ray photoelectron spectroscopy (XPS), high-resolution X-ray diffraction (HRXRD), and Rutherford backscattering spectrometry (RBS). XPS depth-profile shows Sm atoms are uniformly distributed in ceria lattice throughout the bulk of the film. The valence states of Ce and Sm in doped thin films are found to be Ce4+ and Sm3+, respectively. HRXRD shows the samaria doped ceria films on Al2O3(0001) exhibit (111) preferred orientation. Ion-channeling in RBS measurements confirms high quality of the thin films. The resistance of the samaria doped ceria films, obtained by two probe measurement capability under various oxygen pressure (1mTorr-100Torr) and temperatures (623K to 973K), is significantly lower than that of pure ceria under same conditions. The 6Sm% doped ceria film is the optimum composition for highest conductivity. This is attributed to the increased oxygen vacant sites in fluorite crystal structure of the epitaxial thin films which facilitate faster oxygen diffusion through hopping process.

  9. Thin film three-dimensional topological insulator metal-oxide-semiconductor field-effect-transistors: A candidate for sub-10 nm devices

    Energy Technology Data Exchange (ETDEWEB)

    Akhavan, N. D., E-mail: nima.dehdashti@uwa.edu.au; Jolley, G.; Umana-Membreno, G. A.; Antoszewski, J.; Faraone, L. [Department of Electrical, Electronic and Computer Engineering, University of Western Australia, Crawley, WA 6009 (Australia)

    2014-08-28

    Three-dimensional (3D) topological insulators (TI) are a new state of quantum matter in which surface states reside in the bulk insulating energy bandgap and are protected by time-reversal symmetry. It is possible to create an energy bandgap as a consequence of the interaction between the conduction band and valence band surface states from the opposite surfaces of a TI thin film, and the width of the bandgap can be controlled by the thin film thickness. The formation of an energy bandgap raises the possibility of thin-film TI-based metal-oxide-semiconductor field-effect-transistors (MOSFETs). In this paper, we explore the performance of MOSFETs based on thin film 3D-TI structures by employing quantum ballistic transport simulations using the effective continuous Hamiltonian with fitting parameters extracted from ab-initio calculations. We demonstrate that thin film transistors based on a 3D-TI structure provide similar electrical characteristics compared to a Si-MOSFET for gate lengths down to 10 nm. Thus, such a device can be a potential candidate to replace Si-based MOSFETs in the sub-10 nm regime.

  10. Ultrasonic Substrate Vibration-Assisted Drop Casting (SVADC) for the Fabrication of Photovoltaic Solar Cell Arrays and Thin-Film Devices

    Science.gov (United States)

    Eslamian, Morteza; Zabihi, Fatemeh

    2015-12-01

    A simple, low-cost, versatile, and potentially scalable casting method is proposed for the fabrication of micro- and nano-thin films, herein termed as ultrasonic "substrate vibration-assisted drop casting" (SVADC). The impingement of a solution drop onto a substrate in a simple process called drop casting, usually results in spreading of the liquid solution and the formation of a non-uniform thin solid film after solvent evaporation. Our previous and current supporting results, as well as few similar reports by others, confirm that imposing ultrasonic vibration on the substrate can simply convert the uncontrollable drop casting method into a controllable coating technique. Therefore, the SVADC may be used to fabricate an array of emerging thin-film solar cells, such as polymer, perovskite, and quantum-dot solar cells, as well as other small thin-film devices, in a roll-to-roll and automated fabrication process. The preliminary results demonstrate a ten-fold increase in electrical conductivity of PEDOT: PSS made by SVADC compared with the film made by conventional drop casting. Also, simple planar perovskite solar cells made here using SVADC show promising performance with an efficiency of over 3 % for a simple structure without performing process optimization or using expensive materials and treatments.

  11. Band structure engineering for solar energy applications: Zinc oxide(1-x) selenium(x) films and devices

    Science.gov (United States)

    Mayer, Marie Annette

    New technologies motivate the development of new semiconducting materials, for which structural, electrical and chemical properties are not well understood. In addition to new materials systems, there are huge opportunities for new applications, especially in solar energy conversion. In this dissertation I explore the role of band structure engineering of semiconducting oxides for solar energy. Due to the abundance and electrochemical stability of oxides, the appropriate modification could make them appealing for applications in both photovoltaics and photoelectrochemical hydrogen production. This dissertation describes the design, synthesis and evaluation of the alloy ZnO1-xSe x for these purposes. I review several methods of band structure engineering including strain, quantum confinement and alloying. A detailed description of the band anticrossing (BAC) model for highly mismatched alloys is provided, including the derivation of the BAC model as well as recent work and potential applications. Thin film ZnOxSe1-x samples are grown by pulsed laser deposition (PLD). I describe in detail the effect of growth conditions (temperature, pressure and laser fluence) on the chemistry, structure and optoelectronic properties of ZnOxSe1-x. The films are grown using different combinations of PLD conditions and characterized with a variety of techniques. Phase pure films with low roughness and high crystallinity were obtained at temperatures below 450¢ªC, pressures less than 10-4 Torr and laser fluences on the order of 1.5 J/cm 2. Electrical conduction was still observed despite heavy concentrations of grain boundaries. The band structure of ZnO1-xSex is then examined in detail. The bulk electron affinity of a ZnO thin film was measured to be 4.5 eV by pinning the Fermi level with native defects. This is explained in the framework of the amphoteric defect model. A shift in the ZnO1-xSe x valence band edge with x is observed using synchrotron x-ray absorption and emission

  12. Design and test of clamping finger-chain type device for recycling agricultural plastic film%夹指链式残膜回收装置的设计及试验

    Institute of Scientific and Technical Information of China (English)

    段文献; 王吉奎; 李阳; 龚贺贺; 牛海龙; 罗威; 毕新胜

    2016-01-01

    The domestic equipment for recycling agricultural plastic film has the problems of low recovery rate of plastic film, wrapping the film collecting parts by plastics, or difficulty of separating the straw and soil from the film. In addition, film removing for the current methods is poor and high impurity content of recovered plastic film can’t be recycled. In order to solve these problems, the clamping finger-chain type device for recycling agricultural plastic film was designed. The designed device mainly consisted of film collecting device, film removing device, transmission system, side film shoveling, tie rod, transverse beam, residual film box, etc. The film collecting device mainly included film collecting frame, upper film collecting sprocket, under film collecting sprocket, film collecting chain, clamping finger, film cutting saw disk, supporting chain roller, tightening devices, etc. The film removing device mainly included film removing rotation shaft, film removing blade, driving sprocket, film removing bracket, bearing chock, etc. The film collecting device was driven by the ground wheel through the film collecting transmission system and the film removing device was driven by the tractor power output shaft through the film removing transmission. Through the design and mechanical analysis of the clamping finger-chain, the structure size parameters of it were determined, which contained the spacing between two clamping finger-chains was 220 mm, and its working angle was 40°, the effective length of clamping fingerL was 135 mm, and the angle between clamping finger and outer link was 20°. The tension mechanism could make the clamping finger-chain be always in a state of tension in the process of operation. The specification parameters of the selected spring were determined by analysis of the tensioning mechanism. Through the structure size design and motion analysis of film removing device, the film removing blade size was determined, and the length

  13. Simultaneous sampling and analysis of indoor air infested with Cimex lectularius L. (Hemiptera: Cimicidae) by solid phase microextraction, thin film microextraction and needle trap device.

    Science.gov (United States)

    Eom, In-Yong; Risticevic, Sanja; Pawliszyn, Janusz

    2012-02-24

    Air in a room infested by Cimex lectularius L. (Hemiptera: Cimicidae) was sampled simultaneously by three different sampling devices including solid phase microextraction (SPME) fiber coatings, thin film microextraction (TFME) devices, and needle trap devices (NTDs) and then analyzed by gas chromatography-mass spectrometry (GC-MS). The main focus of this study was to fully characterize indoor air by identifying compounds extracted by three different microextraction formats and, therefore, perform both the device comparison and more complete characterization of C. lectularius pheromone. The NTD technique was capable of extracting both (E)-2-hexenal and (E)-2-octenal, which were previously identified as alarm pheromones of bedbugs, and superior NTD recoveries for these two components allowed reliable identification based on mass spectral library searching and linear temperature programmed retention index (LTPRI) technique. While the use of DVB/CAR/PDMS SPME fiber coatings provided complementary sample fingerprinting and profiling results, TFME sampling devices provided discriminative extraction coverage toward highly volatile analytes. In addition to two alarm pheromones, relative abundances of all other analytes were recorded for all three devices and aligned across all examined samples, namely, highly infested area, less infested area, and control samples which were characterized by different bedbug populations. The results presented in the current study illustrate comprehensive characterization of infested indoor air samples through the use of three different non-invasive SPME formats and identification of novel components comprising C. lectularius pheromone, therefore, promising future alternatives for use of potential synthetic pheromones for detection of infestations.

  14. Integrated device architectures for electrochromic devices

    Energy Technology Data Exchange (ETDEWEB)

    Frey, Jonathan Mack; Berland, Brian Spencer

    2015-04-21

    This disclosure describes systems and methods for creating monolithically integrated electrochromic devices which may be a flexible electrochromic device. Monolithic integration of thin film electrochromic devices may involve the electrical interconnection of multiple individual electrochromic devices through the creation of specific structures such as conductive pathway or insulating isolation trenches.

  15. Thickness effects of SiO xN y interlayer inserted between BaTiO 3 insulating layer and ZnS:Mn phosphor layer in thin film electroluminescent devices

    Science.gov (United States)

    Song, M. H.; Lee, Y. H.; Hahn, T. S.; Oh, M. H.; Yoon, K. H.

    1996-09-01

    We investigated the effects of a SiO xN y interlayer on a thin film electroluminescent device, inserted between an amorphous BaTiO 3 thin film and a ZnS:Mn phosphor layer. The effects on the thin film electroluminescent device was studied as a function of the thickness of the interlayer. We found that the introduction of the interlayer affected the growth behavior of the phosphor layer. With increasing thickness of the interlayer, the average grain size and the crystallinity of the phosphor layer was improved. The turn-on voltage of the electroluminescent device increased, and the saturation brightness slightly decreased with increasing interlayer thickness. In the case of the TFELD without the interlayer, Poole-Frenkel conduction was observed in the low dc field region, the devices with the interlayer exhibited effective electron tunneling from interface traps. The efficiency of the devices increased with increasing interlayer thickness.

  16. Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

    Energy Technology Data Exchange (ETDEWEB)

    Hoye, Robert L. Z., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk; MacManus-Driscoll, Judith L., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Muñoz-Rojas, David [LMGP, University Grenoble-Alpes, CNRS, F-3800 Grenoble (France); Nelson, Shelby F. [Kodak Research Laboratories, Eastman Kodak Company, Rochester, New York 14650 (United States); Illiberi, Andrea; Poodt, Paul [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Roozeboom, Fred [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, 5600 MB (Netherlands)

    2015-04-01

    Atmospheric pressure spatial atomic layer deposition (AP-SALD) has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

  17. Investigations of Different Phases Responsible for Changes in Optical Properties of Organic Semiconducting Device Material Thin Films

    Directory of Open Access Journals (Sweden)

    Vivek Kumar Shukla

    2013-01-01

    Full Text Available The environment sensitivity of organic semiconductors may change their molecular structure and hence optical properties. Exploiting this concept, experiments were performed on a green light emitting material bis(8-hydroxy quinolineZinc, (Znq2 used in organic light emitting diodes (OLEDs. Thin films were deposited at varying deposition parameters, and their properties were compared. We investigated that as deposited films have a significant component of Znq2 tetramer out of two known forms, that is, dihydrate and anhydrous tetramer (Znq24, the films deposited at lower deposition rates have higher anhydrous content. The degradation of thin film is shown, that changes the optical properties of film from green emission to blue which may be due to water adsorption and crystallization.

  18. Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye

    2015-04-01

    Full Text Available Atmospheric pressure spatial atomic layer deposition (AP-SALD has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

  19. Characteristics of Nitrogen Doped Diamond-Like Carbon Films Prepared by Unbalanced Magnetron Sputtering for Electronic Devices.

    Science.gov (United States)

    Lee, Jaehyeong; Choi, Byung Hui; Yun, Jung-Hyun; Park, Yong Seob

    2016-05-01

    Synthetic diamond-like carbon (DLC) is a carbon-based material used mainly in cutting tool coatings and as an abrasive material. The market for DLC has expanded into electronics, optics, and acoustics because of its distinct electrical and optical properties. In this work, n-doped DLC (N:DLC) films were deposited on p-type silicon substrates using an unbalanced magnetron sputtering (UBMS) method. We investigated the effect of the working pressure on the microstructure and electrical properties of n-doped DLC films. The structural properties of N:DLC films were investigated by Raman spectroscopy and SEM-EDX, and the electrical properties of films were investigated by observing the changes in the resistivity and current-voltage (I-V) properties. The N:DLC films prepared by UBMS in this study demonstrated good conducting and physical properties with n-doping.

  20. Optical and electrical characterizations of a single step ion beam milling mesa devices of chloride passivated PbS colloidal quantum dots based film

    Science.gov (United States)

    Hechster, Elad; Shapiro, Arthur; Lifshitz, Efrat; Sarusi, Gabby

    2016-07-01

    Colloidal Quantum Dots (CQDs) are of increasing interest, thanks to their quantum size effect that gives rise to their usage in various applications, such as biological tagging, solar cells and as the sensitizing layer of night vision devices. Here, we analyze the optical absorbance of chloride passivated PbS CQDs as well as revealing a correlation between their photoluminescence and sizes distribution, using theoretical models and experimental results from the literature. Next, we calculate the CQDs resistivity as a film. Although resistivity can be calculated from sheet resistance measurement using four point probes, such measurement is usually carried-out on the layer's surface that in most cases has dangling bonds and surface states, which might affect the charges flow and modify the resistivity. Therefore; our approach, which was applied in this work, is to extract the actual resistivity from measurements that are performed along the film's thickness (z-direction). For this intent, we fabricated gold capped PbS mesas devices using a single step Ion Beam Milling (IBM) process where we milled the gold and the PbS film continually, and then measured the vertical resistance. Knowing the mesas' dimensions, we calculate the resistivity. To the best of our knowledge, no previous work has extracted, vertically, the resistivity of chloride passivated PbS CQDs using the above method.

  1. Anomalous elastic properties of RF-sputtered amorphous TeO2+x thin film for temperature-stable SAW device applications.

    Science.gov (United States)

    Dewan, Namrata; Sreenivas, Kondepudy; Gupta, Vinay

    2008-03-01

    The anomalous elastic properties of TeO2+x thin films deposited by rf diode sputtering on substrates at room temperature have been studied. The deposited films are amorphous, and IR spectroscopy reveals the formation of Te-O bond. X-ray photoelectron spectroscopy confirms the variation in the stoichiometry of TeO2+x film from x=0 to 1 with an increase in the oxygen percentage in processing gas composition. The elastic parameters of the films in comparison to the reported values for TeO2+x single crystal are found to be low. However, the temperature coefficients of elastic parameters of all deposited films exhibit anomalous behavior showing positive values for TC(C11) in the range (32.0 to 600.0)x10(-4) degrees C(-1) and TC(C44)=(35.0 to 645.5)x10(-4) degrees C(-1) against the negative values TC(C11)=-2.7x10(-4) degrees C(-1) and TC(C44)=-0.73x10(-4) degrees C(-1) reported for TeO2+x single crystal. The variation in the elastic parameters and their temperature coefficients is correlated with the change in the three-dimensional network of Te-O bonding. The anomalous elastic properties of the TeO2+x films grown in 100% O2 are useful for potential application in the design of temperature stable surface acoustic wave devices.

  2. New devices Si-rich and C-rich a-Si{sub 1−x}C{sub x} thin films gas sensors based

    Energy Technology Data Exchange (ETDEWEB)

    Ouadfel, M.A. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (C.R.T.S.E), 02 Bd., Frantz FANON, B.P. 140, Algiers (Algeria); U.S.T.H.B, Physics Faculty, Physics Materials Laboratory, Algiers (Algeria); Yaddaden, C. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (C.R.T.S.E), 02 Bd., Frantz FANON, B.P. 140, Algiers (Algeria); Merazga, S. [Mentouri Ahmed University, Constantine (Algeria); Cheriet, A.; Talb, L.; Kaci, S.; Belkacem, Y.; Ouadah, Y.; Menous, I. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (C.R.T.S.E), 02 Bd., Frantz FANON, B.P. 140, Algiers (Algeria); Kechouane, M. [U.S.T.H.B, Physics Faculty, Physics Materials Laboratory, Algiers (Algeria); Gabouze, N. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (C.R.T.S.E), 02 Bd., Frantz FANON, B.P. 140, Algiers (Algeria); Keffous, A., E-mail: keffousa@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (C.R.T.S.E), 02 Bd., Frantz FANON, B.P. 140, Algiers (Algeria); Menari, H. [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (C.R.T.S.E), 02 Bd., Frantz FANON, B.P. 140, Algiers (Algeria)

    2013-12-05

    Highlights: •Elaboration of Si-rich and C-rich thin films of amorphous silicon carbide. •Using a co-sputtering d.c magnetron of Si target and different 32–86 of 6H–SiC sprigs. •Structural and optical properties has been performed with applications in environmental field. •Different devices structures based on thin films have been investigated as gas sensor. -- Abstract: In this paper, we present an experimental study on elaboration of Si-rich and C-rich thin films of hydrogenated amorphous silicon carbide (a-Si{sub 1−x}C{sub x}:H) using a DC magnetron co-sputtering of Si single crystal target on which are deposited different polycrystalline 6H–SiC sprigs varying from 32 to 86, with dimension of 10 × 5 mm{sup 2}. A comparative study of structural and optical properties has been performed and its applications in environmental field. The a-Si{sub 1−x}C{sub x}:H films were investigated by scanning electron microscopy (SEM), UV–visible-NIR spectrophotometry, infrared absorption spectroscopy, secondary ion mass spectrometry (SIMS), and photoluminescence. The measured optical gap of a-Si{sub 1−x}C{sub x}:H thin films depend on the carbon concentration with x varying from 0.18 to 0.30. This can be probably explained by the changes of Sp{sup 3} (silicon or film with low carbon content) to sp{sup 2} (high carbon content) configuration. Finally, different devices structures based the thin films have been investigated as gas sensors as Pd/a-Si{sub 0.72}C{sub 0.28}:H with a good sensitivity of CO{sub 2} and H{sub 2} gases at low bias voltage ranging from 0.05 to 0.26 volt, respectively and a low response time of 29 s and 25 s was obtained at 165 ppm of the used gases, with a recovery time of 32 s and 23 s for CO{sub 2} and H{sub 2} gases, respectively.

  3. Bio-photovoltaic conversion device using chlorine-e6 derived from chlorophyll from Spirulina adsorbed on a nanocrystalline TiO2 film electrode.

    Science.gov (United States)

    Amao, Yutaka; Komori, Tasuku

    2004-03-15

    A bio-photovoltaic conversion device based on dye-sensitised solar cell (DSSC) using the visible light sensitisation of chlorine-e6 (Chl-e6) derived from chlorophyll from Spirulina adsorbed on a nanocrystalline TiO2 film was developed. Form fluorescence spectrum of Chl-e6 adsorbed on a nanocrystalline TiO2 film, the emission of Chl-e6 was effectively quenched by TiO2 nanocrystalline indicating that the effective electron injection from the excited singlet state of Chl-e6 into the conduction band of TiO2 particles occurred. The short-circuit photocurrent density (Isc). the open-circuit photovoltage (Voc). and the fill factor (FF) of solar cell using Chl-e6 adsorbed on a nanocrystalline TiO2 film electrode were estimated to be 0.305 +/- 0.012 mA cm(-2), 426 +/- 10 mV, and 45.0%, respectively. IPCE values were reached a maximum around the wavelength of absorption maximum (7.40% at 400 nm; 1.44% at 514 nm and 2.91% at 670 nm), indicating that the DSSC using visible light sensitisation of nanocrystalline TiO2 film by Chl-e6 was developed.

  4. Intrinsic Doping in Electrodeposited ZnS Thin Films for Application in Large-Area Optoelectronic Devices

    Science.gov (United States)

    Madugu, Mohammad Lamido; Olusola, Olajide Ibukun-Olu; Echendu, Obi Kingsley; Kadem, Burak; Dharmadasa, Imyhamy Mudiy

    2016-06-01

    Zinc sulphide (ZnS) thin films with both n- and p-type electrical conductivity were grown on glass/fluorine-doped tin oxide-conducting substrates from acidic and aqueous solution containing ZnSO4 and (NH4)2S2O3 by simply changing the deposition potential in a two-electrode cell configuration. After deposition, the films were characterised using various analytical techniques. X-ray diffraction analysis reveals that the materials are amorphous even after heat treatment. Optical properties (transmittance, absorbance and optical bandgap) of the films were studied. The bandgaps of the films were found to be in the range (3.68-3.86) eV depending on the growth voltage. Photoelectrochemical cell measurements show both n- and p-type electrical conductivity for the films depending on the growth voltage. Scanning electron microscopy shows material clusters on the surface with no significant change after heat treatment at different temperatures. Atomic force microscopy shows that the surface roughness of these materials remain fairly constant reducing only from 18 nm to 17 nm after heat treatment. Thickness estimation of the films was also carried out using theoretical and experimental methods. Direct current conductivity measurements on both as-deposited and annealed films show that resistivity increased after heat treatment.

  5. Toward highly stable solid-state unconventional thin-film battery-supercapacitor hybrid devices: Interfacing vertical core-shell array electrodes with a gel polymer electrolyte

    Science.gov (United States)

    Pandey, Gaind P.; Klankowski, Steven A.; Liu, Tao; Wu, Judy; Li, Jun

    2017-02-01

    A novel solid-state battery-supercapacitor hybrid device is fabricated for high-performance electrical energy storage using a Si anode and a TiO2 cathode in conjunction with a flexible, solid-like gel polymer electrolyte film as the electrolyte and separator. The electrodes were fabricated as three-dimensional nanostructured vertical arrays by sputtering active materials as conformal shells on vertically aligned carbon nanofibers (VACNFs) which serve as the current collector and structural template. Such nanostructured vertical core-shell array-electrodes enable short Li-ion diffusion path and large pseudocapacitive contribution by fast surface reactions, leading to the hybrid features of batteries and supercapacitors that can provide high specific energy over a wide range of power rates. Due to the improved mechanical stability of the infiltrated composite structure, the hybrid cell shows excellent cycling stability and is able to retain more than 95% of the original capacity after 3500 cycles. More importantly, this solid-state device can stably operate in a temperature range from -20 to 60 °C with a very low self-discharge rate and an excellent shelf life. This solid-state architecture is promising for the development of highly stable thin-film hybrid energy storage devices for unconventional applications requiring largely varied power, wider operation temperature, long shelf-life and higher safety standards.

  6. Microstructure and electrical properties of XInZnO (X = Ti, Zr, Hf) films and device performance of their thin film transistors—The effects of employing Group IV-B elements in place of Ga

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Mi Ran [Department of Physics, Institute of Basic Science, Brain Korea 21 Physics Research Division, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jeon, Haseok; Na, Sekwon; Kim, Sunho [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jung, Donggeun [Department of Physics, Institute of Basic Science, Brain Korea 21 Physics Research Division, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Hyoungsub [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Hoo-Jeong, E-mail: hlee@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2013-06-25

    Highlights: ► The effects of adding Group IV B elements have been evaluated in this study. ► Adding alloying elements affected the oxygen vacancy and carrier concentrations, and mobility. ► Adding alloying elements enhanced the bias stability in the order of Ti, Zr and Hf. -- Abstract: In this study, we systematically investigated the effects of employing Group IV-B metals (Ti, Zr, and Hf) in place of Ga in GaInZnO films by fabricating XInZnO films (X = Ti, Zr, or Hf) with a various ratio of the Group IV-B elements. Materials characterization using various analytical methods (including transmission electron microscopy and X-ray photoelectron spectroscopy) elucidates that upon the addition of a small amount of the alloying elements, while the microstructure turned into amorphous from nanocrystalline, the oxygen vacancy concentration decreased systematically along with the carrier concentration. The device characteristics (threshold voltage and field-effect mobility) of the transistors fabricated from the films sensitively reflect the changes in the film properties (carrier concentration and bulk mobility). The bias stability enhanced with the increase of the ratio of the alloying elements to an extent that apparently increases in the order of Ti, Zr and Hf, which is reverse to the order of the electronegativity.

  7. Epitaxial Piezoelectric Pb(Zr0.2Ti0.8O3 Thin Films on Silicon for Energy Harvesting Devices

    Directory of Open Access Journals (Sweden)

    A. Sambri

    2012-01-01

    Full Text Available We report on the properties of ferroelectric Pb(Zr0.2Ti0.8O3 (PZT thin films grown epitaxially on (001 silicon and on the performance of such heterostructures for microfabricated piezoelectric energy harvesters. In the first part of the paper, we investigate the epitaxial stacks through transmission electron microscopy and piezoelectric force microscopy studies to characterize in detail their crystalline structure. In the second part of the paper, we present the electrical characteristics of piezoelectric cantilevers based on these epitaxial PZT films. The performance of such cantilevers as vibration energy transducers is compared with other piezoelectric harvesters and indicates the potential of the epitaxial approach in the field of energy harvesting devices.

  8. Support-Free Transfer of Ultrasmooth Graphene Films Facilitated by Self-Assembled Monolayers for Electronic Devices and Patterns.

    Science.gov (United States)

    Wang, Bin; Huang, Ming; Tao, Li; Lee, Sun Hwa; Jang, A-Rang; Li, Bao-Wen; Shin, Hyeon Suk; Akinwande, Deji; Ruoff, Rodney S

    2016-01-26

    We explored a support-free method for transferring large area graphene films grown by chemical vapor deposition to various fluoric self-assembled monolayer (F-SAM) modified substrates including SiO2/Si wafers, polyethylene terephthalate films, and glass. This method yields clean, ultrasmooth, and high-quality graphene films for promising applications such as transparent, conductive, and flexible films due to the absence of residues and limited structural defects such as cracks. The F-SAM introduced in the transfer process can also lead to graphene transistors with enhanced field-effect mobility (up to 10,663 cm(2)/Vs) and resistance modulation (up to 12×) on a standard silicon dioxide dielectric. Clean graphene patterns can be realized by transfer of graphene onto only the F-SAM modified surfaces.

  9. Electrochemical cell for in situ electrodeposition of magnetic thin films in a superconducting quantum interference device magnetometer.

    Science.gov (United States)

    Topolovec, Stefan; Krenn, Heinz; Würschum, Roland

    2015-06-01

    An electrochemical cell is designed and applied for in situ electrodeposition of magnetic thin films in a commercial SQUID magnetometer system. The cell is constructed in such a way that any parasitic contribution of the cell and of the substrate for electrodeposition to the magnetic moment of the deposited film is reduced to a minimum. A remanent minor contribution is readily taken into account by a proper analysis of the detected signal. Thus, a precise determination of the absolute magnetic moment of the electrodeposited magnetic film during its growth and dissolution is achieved. The feasibility of the cell design is demonstrated by performing Co electrodeposition using cyclic voltammetry. For an average Co film thickness of (35.6 ± 3.0) atomic layers, a magnetic moment per Co atom of (1.75 ± 0.11) μ(B) was estimated, in good agreement with the literature bulk value.

  10. Large area ion beam sputtered YBa2Cu3O(7-delta) films for novel device structures

    Science.gov (United States)

    Gauzzi, A.; Lucia, M. L.; Kellett, B. J.; James, J. H.; Pavuna, D.

    1992-03-01

    A simple single-target ion-beam system is employed to manufacture large areas of uniformly superconducting YBa2Cu3O(7-delta) films which can be reproduced. The required '123' stoichiometry is transferred from the target to the substrate when ion-beam power, target/ion-beam angle, and target temperature are adequately controlled. Ion-beam sputtering is experimentally demonstrated to be an effective technique for producing homogeneous YBa2Cu3O(7-delta) films.

  11. Galvanic corrosion of structural non-stoichiometric silicon nitride thin films and its implications on reliability of microelectromechanical devices

    Energy Technology Data Exchange (ETDEWEB)

    Broas, M., E-mail: mikael.broas@aalto.fi; Mattila, T. T.; Paulasto-Kröckel, M. [Department of Electrical Engineering and Automation, Aalto University, Espoo, P.O. Box 13500, FIN-00076 Aalto (Finland); Liu, X.; Ge, Y. [Department of Materials Science and Engineering, Aalto University, Espoo, P.O. Box 16200, FIN-00076 Aalto (Finland)

    2015-06-28

    This paper describes a reliability assessment and failure analysis of a poly-Si/non-stoichiometric silicon nitride thin film composite structure. A set of poly-Si/SiN{sub x} thin film structures were exposed to a mixed flowing gas (MFG) environment, which simulates outdoor environments, for 90 days, and an elevated temperature and humidity (85 °C/95% R.H.) test for 140 days. The mechanical integrity of the thin films was observed to degrade during exposure to the chemically reactive atmospheres. The degree of degradation was analyzed with nanoindentation tests. Statistical analysis of the forces required to initiate a fracture in the thin films indicated degradation due to the exposure to the MFG environment in the SiN{sub x} part of the films. Scanning electron microscopy revealed a porous-like reaction layer on top of SiN{sub x}. The morphology of the reaction layer resembled that of galvanically corroded poly-Si. Transmission electron microscopy further clarified the microstructure of the reaction layer which had a complex multi-phase structure extending to depths of ∼100 nm. Furthermore, the layer was oxidized two times deeper in a 90 days MFG-tested sample compared to an untested reference. The formation of the layer is proposed to be caused by galvanic corrosion of elemental silicon in non-stoichiometric silicon nitride during hydrofluoric acid etching. The degradation is proposed to be due uncontrolled oxidation of the films during the stress tests.

  12. High Field Electrical Conduction in Pre-Formed Al-ZnS-Al Thin Films in Metal-Insulator-Metal Devices

    Institute of Scientific and Technical Information of China (English)

    M. Y. Nadee; Nadeem Iqbal; M. F. Wasiq; A. U. Khosa

    2007-01-01

    The high field electrical conduction mechanism for the widely used ZnS thin films in the microelectronic industry is investigated. Experimental data on the dc conduction as a function of the applied bias for the Al-ZnS-Al devices is carefully compared with the theoretical equations given by Schottky and Poole-Frenkel. The results yield the value of the coefficient of the barrier lowering compatible with the Schottky theory rather than the Poole-Frenkel theory, which are also in agreement with the results reported earlier by Maskawa [Phys. Rev. Lett.24(1970) 1175

  13. Novel Finding of Widespread Occurrence and Accumulation of Bisphenol A Diglycidyl Ethers (BADGEs) and Novolac Glycidyl Ethers (NOGEs) in Marine Mammals from the United States Coastal Waters.

    Science.gov (United States)

    Xue, Jingchuan; Kannan, Kurunthachalam

    2016-02-16

    Bisphenol A diglycidyl ether (BADGE)- and bisphenol F diglycidyl ether (BFDGE)-based epoxy resins have a broad range of applications, including serving as inner coatings of food and beverage cans and as protective coatings in marine construction. Prior to this study, no studies had examined the occurrence and bioaccumulation of BADGEs or BFDGEs in aquatic organisms. In this study, BADGE, BFDGE, and nine of their derivatives were determined in 121 tissue (liver, kidney, blubber, and brain) samples from eight species of marine mammals collected from the U.S. coastal waters of Florida, California, Washington, and Alaska. BADGE·2HCl was the predominant compound found in the majority (78.5%) of the marine mammal tissues analyzed, at concentrations of up to 2950 ng/g (wet weight (wt)) found in the liver of a sea otter from Kachemak Bay, Alaska. The measured concentrations of BADGE·2HCl in marine mammals were on the order of hundreds of nanograms per gram tissue, which are some of the highest concentrations ever reported for this compound in biota. Males contained greater concentrations of BADGE·2HCl than did females. BADGE·2HCl also was found in the brain tissues of sea otters. Trace levels of BADGE·2HCl were found in the livers of polar bears from Alaska, which suggested that BADGEs are widely distributed in the oceanic environment.

  14. Fabrication and examination of epitaxial HTSC/isolator thin films on sapphire substrates for application in high frequency devices; Herstellung und Untersuchung von epitaktischen HTSL/Isolator-Schichten auf Saphirsubstraten zur Anwendung in HF-Bauelementen

    Energy Technology Data Exchange (ETDEWEB)

    Kittel, H.

    1995-10-01

    The use of high temperature superconductors (HTSC) like YBCO with distinct lower surface resistance compared to normal conductors allows miniaturisation of high frequency (HF) circuits. The object of this work was the fabrication of YBCO thin films on low loss sapphire substrates applicable for stripline devices. To induce epitaxial growth and to avoid chemical reaction at the film-substrate boundary buffer layers were investigated. The examination of the growth properties and especially of the surface impedance has been allotted particular importance. In contrast to CaTiO{sub 3} it was possible to deposit CeO{sub 2}-buffer layers in direct growth up to a thickness of about 30 nm without cracks. The films show all growth properties required and even Laue-oscillations being a feature of high quality growth enabling the determination of film thickness distribution without destruction. The YBCO growth-, transport- and HF-properties meet the ones of YBCO films on standard substrates. A remarkable result is that the mosaic distribution of the CEO film, itself strongly dependend on film thickness, does not influence that of the YBCO film considerably. Rather it changes its shape subsequently due to YBCO deposition. A further particularity in contrast to deposition on standard substrates is the need to adjust the substrate heater tempeature for deposition of YBCO films with thicknesses {>=}300 nm needed for HF application. To demonstrate their usefullness some stripline devices like planar coils and side coupled filters have been fabricated and characterised. (orig.)

  15. Influence of electron beam irradiation on nonlinear optical properties of Al doped ZnO thin films for optoelectronic device applications in the cw laser regime

    Science.gov (United States)

    Antony, Albin; Pramodini, S.; Poornesh, P.; Kityk, I. V.; Fedorchuk, A. O.; Sanjeev, Ganesh

    2016-12-01

    We present the studies on third-order nonlinear optical properties of Al doped ZnO thin films irradiated with electron beam at different dose rate. Al doped ZnO thin films were deposited on a glass substrate by spray pyrolysis deposition technique. The thin films were irradiated using the 8 MeV electron beam from microtron ranging from 1 kG y to 5 kG y. Nonlinear optical studies were carried out by employing the single beam Z-scan technique to determine the sign and magnitude of absorptive and refractive nonlinearities of the irradiated thin films. Continuous wave He-Ne laser operating at 633 nm was used as source of excitation. The open aperture Z-scan measurements indicated the sample displays reverse saturable absorption (RSA) process. The negative sign of the nonlinear refractive index n2 was noted from the closed aperture Z-scan measurements indicates, the films exhibit self-defocusing property due to thermal nonlinearity. The third-order nonlinear optical susceptibility χ(3) varies from 8.17 × 10-5 esu to 1.39 × 10-3 esu with increase in electron beam irradiation. The present study reveals that the irradiation of electron beam leads to significant changes in the third-order optical nonlinearity. Al doped ZnO displays good optical power handling capability with optical clamping of about ∼5 mW. The irradiation study endorses that the Al doped ZnO under investigation is a promising candidate photonic device applications such as all-optical power limiting.

  16. Enhanced performance of CdS/CdTe thin-film devices through temperature profiling techniques applied to close-spaced sublimation deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xiaonan Li; Sheldon, P.; Moutinho, H.; Matson, R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    The authors describe a methodology developed and applied to the close-spaced sublimation technique for thin-film CdTe deposition. The developed temperature profiles consisted of three discrete temperature segments, which the authors called the nucleation, plugging, and annealing temperatures. They have demonstrated that these temperature profiles can be used to grow large-grain material, plug pinholes, and improve CdS/CdTe photovoltaic device performance by about 15%. The improved material and device properties have been obtained while maintaining deposition temperatures compatible with commercially available substrates. This temperature profiling technique can be easily applied to a manufacturing environment by adjusting the temperature as a function of substrate position instead of time.

  17. Thin films of copper oxide and copper grown by atomic layer deposition for applications in metallization systems of microelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Waechtler, Thomas

    2010-05-25

    Copper-based multi-level metallization systems in today's ultralarge-scale integrated electronic circuits require the fabrication of diffusion barriers and conductive seed layers for the electrochemical metal deposition. Such films of only several nanometers in thickness have to be deposited void-free and conformal in patterned dielectrics. The envisaged further reduction of the geometric dimensions of the interconnect system calls for coating techniques that circumvent the drawbacks of the well-established physical vapor deposition. The atomic layer deposition method (ALD) allows depositing films on the nanometer scale conformally both on three-dimensional objects as well as on large-area substrates. The present work therefore is concerned with the development of an ALD process to grow copper oxide films based on the metal-organic precursor bis(trin- butylphosphane)copper(I)acetylacetonate [({sup n}Bu{sub 3}P){sub 2}Cu(acac)]. This liquid, non-fluorinated {beta}-diketonate is brought to react with a mixture of water vapor and oxygen at temperatures from 100 to 160 C. Typical ALD-like growth behavior arises between 100 and 130 C, depending on the respective substrate used. On tantalum nitride and silicon dioxide substrates, smooth films and selfsaturating film growth, typical for ALD, are obtained. On ruthenium substrates, positive deposition results are obtained as well. However, a considerable intermixing of the ALD copper oxide with the underlying films takes place. Tantalum substrates lead to a fast self-decomposition of the copper precursor. As a consequence, isolated nuclei or larger particles are always obtained together with continuous films. The copper oxide films grown by ALD can be reduced to copper by vapor-phase processes. If formic acid is used as the reducing agent, these processes can already be carried out at similar temperatures as the ALD, so that agglomeration of the films is largely avoided. Also for an integration with subsequent

  18. Study of p-type AlN-doped SnO2 thin films and its transparent devices

    Science.gov (United States)

    Wu, Y. J.; Liu, Y. S.; Hsieh, C. Y.; Lee, P. M.; Wei, Y. S.; Liao, C. H.; Liu, C. Y.

    2015-02-01

    The electrical properties of transparent Al-doped tin oxide (SnO2), N-doped SnO2, and AlN-doped SnO2 thin films were studied. The Al-doped tin oxide (SnO2) thin films all show n-type conduction regardless the annealing condition. The n-type conduction of the as-deposited N-doped SnO2, and AlN-doped SnO2 thin films could be converted to p-type conduction by annealing the films at an elevated temperature of 450 °C. XPS analysis verified that the substitution of N ions in the O ion sites in the annealed N-doped SnO2 and AlN-doped SnO2 thin films were responsible for the n-p conduction transition. The conduction of the annealed N-doped SnO2 and AlN-doped SnO2 thin films could be converted back to n-type conduction by thermally annealing the films at higher temperature, over 450 °C. The p-n conduction transition is related with the outgassing of N ions in the p-type N-doped SnO2 and AlN-doped SnO2 thin films. Remarkably, we found that the Al content can retard the outgassing of N ions in the p-type N-doped SnO2 and AlN-doped SnO2 thin films and prolong the p-n conduction transition temperature above 600 °C. XPS analysis revealed that the formation of the Snsbnd Nsbnd Al bond improved the stability of the N ions in the AlN-doped SnO2 thin films. I-V curve of the p-type AlN-doped SnO2/n-type fluorine-doped SnO2 junction exhibited clear p-n junction characteristics, a low leakage current under the revised bias (1.13 × 10-5 A at -5 V), and a low turn-on voltage (3.24 V). p-Type AlN-doped SnO2/n-type fluorine-doped SnO2 junction exhibited excellent transmittance (over 90%) in the visible region (470-750 nm).

  19. Mechanical properties of amorphous indium–gallium–zinc oxide thin films on compliant substrates for flexible optoelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, D.W., E-mail: DWM172@bham.ac.uk [University of Birmingham, School of Metallurgy and Materials, Edgbaston, Birmingham, B15 2TT (United Kingdom); Waddingham, R.; Flewitt, A.J. [University of Cambridge, Electrical Engineering Division, Department of Engineering, J J Thomson Avenue, Cambridge CB3 0FA,United Kingdom (United Kingdom); Sierros, K.A. [West Virginia University, Mechanical & Aerospace Engineering, Morgantown, WV 26506 (United States); Bowen, J. [Open University, Department of Engineering and Innovation, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Kukureka, S.N. [University of Birmingham, School of Metallurgy and Materials, Edgbaston, Birmingham, B15 2TT (United Kingdom)

    2015-11-02

    Amorphous indium–gallium–zinc-oxide (a-IGZO) thin films were deposited using RF magnetron sputtering on polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) flexible substrates and their mechanical flexibility investigated using uniaxial tensile and buckling tests coupled with in situ optical microscopy. The uniaxial fragmentation test demonstrated that the crack onset strain of the IGZO/PEN was ~ 2.9%, which is slightly higher than that of IGZO/PET. Also, uniaxial tensile crack density analysis suggests that the saturated crack spacing of the film is strongly dependent on the mechanical properties of the underlying polymer substrate. Buckling test results suggest that the crack onset strain (equal to ~ 1.2%, of the IGZO/polymer samples flexed in compression to ~ 5.7 mm concave radius of curvature) is higher than that of the samples flexed with the film being in tension (convex bending) regardless whether the substrate is PEN or PET. The saturated crack density of a-IGZO film under the compression buckling mode is smaller than that of the film under the tensile buckling mode. This could be attributed to the fact that the tensile stress encouraged this crack formation originating from surface defects in the coating. It could also be due to the buckling delamination of the thin coating from the substrate at a lower strain than that at which a crack initiates during flexing in compression. These results provide useful information on the mechanical reliability of a-IGZO films for the development of flexible electronics. - Highlights: • Mechanical flexibility of IGZO thin films investigated by uniaxial tensile and buckling tests • Uniaxial fragmentation gives crack onset strain for IGZO/PEN of 2.9% (higher than for IGZO/PET.) • Saturated crack spacing strongly dependent on mechanical properties of polymer substrate • Crack onset strain in concave bending higher than in convex bending for both substrates.

  20. Characterization of Sputtered CdTe Thin Films with Electron Backscatter Diffraction and Correlation with Device Performance.

    Science.gov (United States)

    Nowell, Matthew M; Scarpulla, Michael A; Paudel, Naba R; Wieland, Kristopher A; Compaan, Alvin D; Liu, Xiangxin

    2015-08-01

    The performance of polycrystalline CdTe photovoltaic thin films is expected to depend on the grain boundary density and corresponding grain size of the film microstructure. However, the electrical performance of grain boundaries within these films is not well understood, and can be beneficial, harmful, or neutral in terms of film performance. Electron backscatter diffraction has been used to characterize the grain size, grain boundary structure, and crystallographic texture of sputtered CdTe at varying deposition pressures before and after CdCl2 treatment in order to correlate performance with microstructure. Weak fiber textures were observed in the as-deposited films, with (111) textures present at lower deposition pressures and (110) textures observed at higher deposition pressures. The CdCl2-treated samples exhibited significant grain recrystallization with a high fraction of twin boundaries. Good correlation of solar cell efficiency was observed with twin-corrected grain size while poor correlation was found if the twin boundaries were considered as grain boundaries in the grain size determination. This implies that the twin boundaries are neutral with respect to recombination and carrier transport.

  1. Growth and characterization of piezoelectric AlN thin films for diamond-based surface acoustic wave devices

    Energy Technology Data Exchange (ETDEWEB)

    Benetti, M. [C.N.R. Istituto di Acustica ' O. M. Corbino' , Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Cannata, D. [C.N.R. Istituto di Acustica ' O. M. Corbino' , Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Di Pietrantonio, F. [C.N.R. Istituto di Acustica ' O. M. Corbino' , Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Verona, E. [C.N.R. Istituto di Acustica ' O. M. Corbino' , Via del Fosso del Cavaliere 100, 00133 Rome (Italy)]. E-mail: enrico.verona@idac.rm.cnr.it; Generosi, A. [C.N.R. Istituto di Struttura della Materia, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Paci, B. [C.N.R. Istituto di Struttura della Materia, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Rossi Albertini, V. [C.N.R. Istituto di Struttura della Materia, Via del Fosso del Cavaliere 100, 00133 Rome (Italy)

    2006-02-21

    We report on the preparation and structural characterization of piezoelectric films of aluminium nitride onto diamond substrates. The samples were fabricated by sequential radio frequency reactive diode sputtering processes, carried out at various temperatures, in a head vacuum system starting from stechiometric targets. The structural characterization of the films was performed by energy dispersive X-ray diffraction analysis. The deposition temperature was found to play a relevant role to obtain highly textured films with the c-axis perpendicular to the substrate surface, as required by surface-acoustic-wave applications. In particular, a minimum substrate temperature of 300 deg. C was needed in order to obtain any internal order along the c-axis while, increasing the temperature, the AlN <002> orientation becomes preferential. The rocking curve analysis revealed a good crystalline quality of the AlN films whose degree of epitaxy can be well described by a linearly increasing function of the temperature at which the films are grown.

  2. Characterization of ZnO Interlayers for Organic Solar Cells: Correlation of Electrochemical Properties with Thin-Film Morphology and Device Performance.

    Science.gov (United States)

    Ou, Kai-Lin; Ehamparam, Ramanan; MacDonald, Gordon; Stubhan, Tobias; Wu, Xin; Shallcross, R Clayton; Richards, Robin; Brabec, Christoph J; Saavedra, S Scott; Armstrong, Neal R

    2016-08-03

    This report focuses on the evaluation of the electrochemical properties of both solution-deposited sol-gel (sg-ZnO) and sputtered (sp-ZnO) zinc oxide thin films, intended for use as electron-collecting interlayers in organic solar cells (OPVs). In the electrochemical studies (voltammetric and impedance studies), we used indium-tin oxide (ITO) over coated with either sg-ZnO or sp-ZnO interlayers, in contact with either plain electrolyte solutions, or solutions with probe redox couples. The electroactive area of exposed ITO under the ZnO interlayer was estimated by characterizing the electrochemical response of just the oxide interlayer and the charge transfer resistance from solutions with the probe redox couples. Compared to bare ITO, the effective electroactive area of ITO under sg-ZnO films was ca. 70%, 10%, and 0.3% for 40, 80, and 120 nm sg-ZnO films. More compact sp-ZnO films required only 30 nm thicknesses to achieve an effective electroactive ITO area of ca. 0.02%. We also examined the electrochemical responses of these same ITO/ZnO heterojunctions overcoated with device thickness pure poly(3-hexylthiophehe) (P3HT), and donor/acceptor blended active layers (P3HT:PCBM). Voltammetric oxidation/reduction of pure P3HT thin films on ZnO/ITO contacts showed that pinhole pathways exist in ZnO films that permit dark oxidation (ITO hole injection into P3HT). In P3HT:PCBM active layers, however, the electrochemical activity for P3HT oxidation is greatly attenuated, suggesting PCBM enrichment near the ZnO interface, effectively blocking P3HT interaction with the ITO contact. The shunt resistance, obtained from dark current-voltage behavior in full P3HT/PCBM OPVs, was dependent on both (i) the porosity of the sg-ZnO or sp-ZnO films (as revealed by probe molecule electrochemistry) and (ii) the apparent enrichment of PCBM at ZnO/P3HT:PCBM interfaces, both effects conveniently revealed by electrochemical characterization. We anticipate that these approaches will be

  3. An in vivo pilot study of a microporous thin film nitinol-covered stent to assess the effect of porosity and pore geometry on device interaction with the vessel wall.

    Science.gov (United States)

    Chun, Youngjae; Kealey, Colin P; Levi, Daniel S; Rigberg, David A; Chen, Yanfei; Tillman, Bryan W; Mohanchandra, K P; Shayan, Mahdis; Carman, Gregory P

    2017-03-01

    Sputter-deposited thin film nitinol constructs with various micropatterns were fabricated to evaluate their effect on the vessel wall in vivo when used as a covering for commercially available stents. Thin film nitinol constructs were used to cover stents and deployed in non-diseased swine arteries. Swine were sacrificed after approximately four weeks and the thin film nitinol-covered stents were removed for histopathologic evaluation. Histopathology revealed differences in neointimal thickness that correlated with the thin film nitinol micropattern. Devices covered with thin film nitinol with a lateral × vertical length = 20 × 40 µm diamond pattern had minimal neointimal growth with well-organized cell architecture and little evidence of ongoing inflammation. Devices covered with thin film nitinol with smaller fenestrations exhibited a relatively thick neointimal layer with inflammation and larger fenestrations showed migration of inflammatory and smooth muscle cells through the micro fenestrations. This "proof-of-concept" study suggests that there may be an ideal thin film nitinol porosity and pore geometry to encourage endothelialization and incorporation of the device into the vessel wall. Future work will be needed to determine the optimal pore size and geometry to minimize neointimal proliferation and in-stent stenosis.

  4. Thermal annealing and magnetic anisotropy of NiFe thin films on n{sup +}-Si for spintronic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Q.H. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Huang, R. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Wang, L.S. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Wu, Z.G., E-mail: zgwu@lzu.edu.cn [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, C., E-mail: lich@xmu.edu.cn [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Luo, Q. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Zuo, S.Y. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, J. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Peng, D.L. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Han, G.L. [Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Yan, P.X. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2015-11-15

    To ensure that the magnetic metal electrodes can meet the requirements of the spin injection, NiFe films prepared both on HfO{sub 2} dielectric layer and n{sup +}-Si directly by sputtering deposition, and treated by conventional furnace annealing and/or high vacuum magnetic field annealing were investigated. It was found that thermal annealing at 250 °C improved the crystalline quality and reduced surface roughness of the NiFe films, thus enhancing its saturation magnetization intensity. The 100 nm thick NiFe films had too large coercive force and saturation magnetization intensity in vertical direction to meet the requirements of Hanle curve detection. While, 30 nm thick NiFe films showed paramagnetic hysteresis loops in vertical direction, and the magnetization intensity of the sample after annealing at 250 °C for 30 min was less than 2% to the parallel when the external magnetic field was given between ±10 Oe. This was preferred to Hanle curve detection. The thin HfO{sub 2} dielectric layer between metal and Si partially suppressed the diffusion of Ni in NiFe into Si substrate and formation of NiSi, greatly enhancing the saturation magnetization intensity of the Al/NiFe/HfO{sub 2}/Si sample by thermal annealing. Those results suggest that Al/NiFe/HfO{sub 2}/Si structure, from the point view of magnetic electrodes, would be suitable for spin injection and detection applications. - Highlights: • The saturation magnetization intensity of NiFe thin-film was enhanced by thermal annealing. • A paramagnetic hysteresis loop of NiFe thin-film was observed in vertical direction. • The thin HfO{sub 2} dielectric layer between NiFe and Si partially suppressed the diffusion of Ni into Si.

  5. Optical and electrical characterizations of a single step ion beam milling mesa devices of chloride passivated PbS colloidal quantum dots based film

    Energy Technology Data Exchange (ETDEWEB)

    Hechster, Elad, E-mail: elad.hechster@gmail.com; Sarusi, Gabby [Electro-Optics Engineering Unit and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 84100 Israel (Israel); Shapiro, Arthur; Lifshitz, Efrat [Schulich Faculty of Chemistry, Solid State Institute, Russel Berrie Nanotechnology Institute, Technion – Israel Institute of technology, 32000 Haifa (Israel)

    2016-07-15

    Colloidal Quantum Dots (CQDs) are of increasing interest, thanks to their quantum size effect that gives rise to their usage in various applications, such as biological tagging, solar cells and as the sensitizing layer of night vision devices. Here, we analyze the optical absorbance of chloride passivated PbS CQDs as well as revealing a correlation between their photoluminescence and sizes distribution, using theoretical models and experimental results from the literature. Next, we calculate the CQDs resistivity as a film. Although resistivity can be calculated from sheet resistance measurement using four point probes, such measurement is usually carried-out on the layer’s surface that in most cases has dangling bonds and surface states, which might affect the charges flow and modify the resistivity. Therefore; our approach, which was applied in this work, is to extract the actual resistivity from measurements that are performed along the film’s thickness (z-direction). For this intent, we fabricated gold capped PbS mesas devices using a single step Ion Beam Milling (IBM) process where we milled the gold and the PbS film continually, and then measured the vertical resistance. Knowing the mesas’ dimensions, we calculate the resistivity. To the best of our knowledge, no previous work has extracted, vertically, the resistivity of chloride passivated PbS CQDs using the above method.

  6. Bifunctional MoO3-WO3/Ag/MoO3-WO3 Films for Efficient ITO-Free Electrochromic Devices.

    Science.gov (United States)

    Dong, Wenjie; Lv, Ying; Xiao, Lili; Fan, Yi; Zhang, Nan; Liu, Xingyuan

    2016-12-14

    Dielectric-metal-dielectric (DMD) trilayer films, served as both electrochromic (EC) film and transparent conductor (TC), have exhibited great potential application in low-cost, ITO-free electrochromic devices (ECDs). However, recent reports on the DMD-based ECDs revealed that the response time and the optical modulation properties were not very satisfactory. Here, the mixed MoO3-WO3 materials were first introduced as the dielectric layer to construct an EC-TC bifunctional MoO3-WO3/Ag/MoO3-WO3 (MWAMW) film, which demonstrates strong and broad-band optical modulation in the visible light region, fast color-switching time (2.7 s for coloration and 4.1 s for bleaching), along with high coloration efficiency (70 cm(2) C(-1)). The electrical structure and electrochemical reaction kinetics analysis revealed that the improved EC performances are associated with the increased electron intervalence transition together with the fast charge-transfer and ion-diffusion dynamics.

  7. Pulsed Nd:YAG laser deposition of indium tin oxide thin films in different gases and organic light emitting device applications

    Energy Technology Data Exchange (ETDEWEB)

    Yong, T.Y. [Faculty of Engineering, Multimedia University, Cyberjaya, 63100 Selangor (Malaysia); Tou, T.Y. [Faculty of Engineering, Multimedia University, Cyberjaya, 63100 Selangor (Malaysia)], E-mail: tytou@mmu.edu.my; Yow, H.K. [Faculty of Engineering, Multimedia University, Cyberjaya, 63100 Selangor (Malaysia); Safran, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, 1121 Konkoly-Thege ut 29-33, Budapest XII (Hungary)

    2008-04-30

    The microstructures, electrical and optical properties of indium-doped tin oxide (ITO) films, deposited on glass substrates in different background gases by a pulsed Nd:YAG laser, were characterized. The optimal pressure for obtaining the lowest resistivity in ITO thin film is inversely proportional to the molecular weight of the background gases, namely the argon (Ar), oxygen (O{sub 2}), nitrogen (N{sub 2}) and helium (He). While substrate heating to 250 deg. C decreased the ITO resistivity to < 4 x 10{sup -4} {omega} cm, obtaining the optical transmittance of higher than 90% depended mainly on the background gas pressure for O{sub 2} and Ar. Obtaining the lowest ITO resistivity, however, did not beget a high optical transmittance for ITO deposition in N{sub 2} and He. Scanning electron microscope pictures show distinct differences in microstructures due to the background gas: nanostructures when using Ar and N{sub 2} but polycrystalline for using O{sub 2} and He. The ITO surface roughness varied with the deposition distance. The effects on the molecularly doped, single-layer organic light emitting device (OLED) operation and performance were also investigated. Only ITO thin films prepared in O{sub 2} and Ar are suitable for the fabrication OLED with performance comparable to that fabricated on the commercially available, magnetron-sputtered ITO.

  8. Flexible, Transparent, Thickness-Controllable SWCNT/PEDOT:PSS Hybrid Films Based on Coffee-Ring Lithography for Functional Noncontact Sensing Device

    KAUST Repository

    Tai, Yanlong

    2015-12-08

    Flexible transparent conductive films (FTCFs) as the essential components of the next generation of functional circuits and devices are presently attracting more attention. Here, a new strategy has been demonstrated to fabricate thickness-controllable FTCFs through coffee ring lithography (CRL) of single-wall carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT:PSS) hybrid ink. The influence of ink concentration and volume on the thickness and size of hybrid film has been investigated systematically. Results show that the final FTCFs present a high performance, including a homogeneous thickness of 60-65 nm, a sheet resistance of 1.8 kohm/sq, a visible/infrared-range transmittance (79%, PET = 90%), and a dynamic mechanical property (>1000 cycle, much better than ITO film), respectively, when SWCNT concentration is 0.2 mg/mL, ink volume is 0.4 μL, drying at room temperature. Moreover, the benefits of these kinds of FTCFs have been verified through a full transparent, flexible noncontact sensing panel (3 × 4 sensing pixels) and a flexible battery-free wireless sensor based on a humidity sensing mechanism, showing excellent human/machine interaction with high sensitivity, good stability, and fast response/recovery ability. © 2015 American Chemical Society.

  9. Integrated optical and electrical modeling of plasmon-enhanced thin film photovoltaics: A case-study on organic devices

    Science.gov (United States)

    Rourke, Devin; Ahn, Sungmo; Nardes, Alexandre M.; van de Lagemaat, Jao; Kopidakis, Nikos; Park, Wounjhang

    2014-09-01

    The nanoscale light control for absorption enhancement of organic photovoltaic (OPV) devices inevitably produces strongly non-uniform optical fields. These non-uniformities due to the localized optical modes are a primary route toward absorption enhancement in OPV devices. Therefore, a rigorous modeling tool taking into account the spatial distribution of optical field and carrier generation is necessary. Presented here is a comprehensive numerical model to describe the coupled optical and electrical behavior of plasmon-enhanced polymer:fullerene bulk heterojunction (BHJ) solar cells. In this model, a position-dependent electron-hole pair generation rate that could become highly non-uniform due to photonic nanostructures is directly calculated from the optical simulations. By considering the absorption and plasmonic properties of nanophotonic gratings included in two different popular device architectures, and applying the Poisson, current continuity, and drift/diffusion equations, the model predicts quantum efficiency, short-circuit current density, and desired carrier mobility ratios for bulk heterojunction devices incorporating nanostructures for light management. In particular, the model predicts a significant degradation of device performance when the carrier species with lower mobility are generated far from the collecting electrode. Consequently, an inverted device architecture is preferred for materials with low hole mobility. This is especially true for devices that include plasmonic nanostructures. Additionally, due to the incorporation of a plasmonic nanostructure, we use simulations to theoretically predict absorption band broadening of a BHJ into energies below the band gap, resulting in a 4.8% increase in generated photocurrent.

  10. Historical Evaluation of Film Badge Dosimetry Y-12 Plant: Part 2–Neutron Radiation ORAUT-OTIB-0045

    Energy Technology Data Exchange (ETDEWEB)

    Kerr GD, Frome EL, Watkins JP, Tankersley WG

    2009-12-14

    A summary of the major neutron sources involved in radiation exposures to Y-12 workers is presented in this TIB. Graphical methods are used to evaluate available neutron dose data from quarterly exposures to Y-12 workers and to determine how the data could be used to derive neutron-to-gamma dose ratios for dose reconstruction purposes. This TIB provides estimates of neutron-to-gamma dose ratios for specific departments and a default value for the neutron-to-gamma dose ratio based on the pooled neutron dose data for all Y-12 departments.

  11. Photovoltaic devices based on electrochemical-chemical deposited CdS and poly3-octylthiophene thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Hailin [Departamento de Materiales Solares, Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Priv.Xochicalco S/N, Temixco, Morelos 62580 (Mexico); University of California, Natural Science II, Irvine, CA 92697 (United States); Kung, Sheng-Chin; Yang, Li-Mei; Penner, Reginald M. [University of California, Natural Science II, Irvine, CA 92697 (United States); Nicho, M.E. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Chamilpa, Morelos 62110 (Mexico)

    2009-01-15

    Cadmium sulfide (CdS) is a well-known wide bandgap semiconductor for solar cell applications. In this work we report an electrochemical/chemical method to prepare CdS thin films on gold (Au)-coated glass substrates. 10 nm thick of titanium (Ti) film was first sputtered on glass surface to improve the adhesion between the subsequent sputtered Au film and the glass surface. Cadmium films were then electrochemically deposited on Au surface in an acidic solution with negative potential, and the obtained glass/Ti/Au/Cd samples were annealed in H{sub 2}S atmosphere to convert Cd into CdS. XRD pattern of H{sub 2}S-annealed Cd samples shows a hexagonal wurtzite phase in CdS with (0 0 2) as the preferential crystalline plane. Photovoltaic properties were clearly shown in hybrid heterojunctions of CdS and poly3-octylthiophene (P3OT) with Au as the top and the back metal contacts. (author)

  12. Handheld and automated ultrasonic spray deposition of conductive PEDOT:PSS films and their application in AC EL devices

    NARCIS (Netherlands)

    Ely, Fernando; Matsumoto, Agatha; Zoetebier, Bram; Peressinotto, Valdirene S.; Hirata, Marcelo Kioshi; Sousa, de Douglas A.; Maciel, Rubens

    2014-01-01

    In this contribution we explore the spray deposition technique to achieve smooth films based on the conductive polymer PEDOT:PSS. Two different spray systems were used and compared namely: (a) handheld airbrush and (b) automated ultrasonic spray system. For each system a number of parameters were pr

  13. Handheld and automated ultrasonic spray deposition of conductive PEDOT:PSS films and their application in AC EL devices

    NARCIS (Netherlands)

    Ely, Fernando; Matsumoto, Agatha; Zoetebier, Bram; Peressinotto, Valdirene S.; Hirata, Marcelo Kioshi; de Sousa, Douglas A.; Maciel, Rubens

    2014-01-01

    In this contribution we explore the spray deposition technique to achieve smooth films based on the conductive polymer PEDOT:PSS. Two different spray systems were used and compared namely: (a) handheld airbrush and (b) automated ultrasonic spray system. For each system a number of parameters were

  14. Electrical characterization and device characterization of ZnO microring shaped films by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Yakuphanoglu, Fahrettin, E-mail: fyhan@hotmail.co [Firat University, Physics Department, Faculty of Science and Arts, 23119, Elazig (Turkey)

    2010-09-24

    Research highlights: {yields} Zinc oxide microrings formed nanoparticles were prepared by Sol Gel method. {yields} The ZnO film exhibits a polycrystalline grown with a hexagonal wurtzite-type and optical band gap of 3.22 eV. {yields} Au/n-ZnO/n-Si Schottky diode exhibits a rectifying behavior with a higher ideality factor of 2.01 and barrier height of 0.80 eV. - Abstract: Zinc oxide microrings formed nanoparticles were prepared on n-type silicon substrate by sol-gel method. The structure of ZnO film is confirmed by XRD analysis and ZnO film exhibits a polycrystalline grown with a hexagonal wurtzite-type. The optical band gap of the ZnO film deposited on silicon substrate was determined using the reflectance spectra by means of Kubelka-Munk formula and was found to be 3.22 eV. The structural properties of the ZnO film were investigated by atomic force microscopy. The AFM results indicate that the ZnO film is consisted of microrings with nanoparticles. A single phase of ZnO microring with outer diameter is ranging from 2.2 {mu}m to 1.72 {mu}m and inner diameters ranging from 125 nm to 470 nm was obtained. A Schottky diode having Au/n-type ZnO plus n-type silicon structure was fabricated. The current-voltage and impedance spectroscopy properties of the diode have been investigated. The barrier height {phi}{sub b} and ideality factor n values for the diode were found to be 0.80 eV and 2.01, respectively. The series resistance for the diode was calculated from the admittance behavior in accumulation region. The interface state density profile for the diode was obtained. The obtained results indicate that the electric parameters of the diode are affected by structural properties of ZnO film.

  15. High-frequency Lamb wave device composed of MEMS structure using LiNbO3 thin film and air gap.

    Science.gov (United States)

    Kadota, Michio; Ogami, Takashi; Yamamoto, Kansho; Tochishita, Hikari; Negoro, Yasuhiro

    2010-11-01

    High-frequency devices operating at 3 GHz or higher are required, for instance, for future 4th generation mobile phone systems in Japan. Using a substrate with a high acoustic velocity is one method to realize a high-frequency acoustic or elastic device. A Lamb wave has a high velocity when the substrate thickness is thin. To realize a high-frequency device operating at 3 GHz or higher using a Lamb wave, a very thin (less than 0.5 μm thick) single-crystal plate must be used. It is difficult to fabricate such a very thin single crystal plate. The authors have attempted to use a c-axis orientated epitaxial LiNbO(3) thin film deposited by a chemical vapor deposition system (CVD) instead of using a thin LiNbO(3) single crystal plate. Lamb wave resonators composed of a interdigital transducer (IDT)/the LiNbO(3) film/air gap/base substrate structure like micro-electromechanical system (MEMS) transducers were fabricated. These resonators have shown a high frequency of 4.5 and 6.3 GHz, which correspond to very high acoustic velocities of 14,000 and 12,500 m/s, respectively, have excellent characteristics such as a ratio of resonant and antiresonant impedance of 52 and 38 dB and a wide band of 7.2% and 3.7%, respectively, and do not have spurious responses caused by the 0th modes of shear horizontal (SH(0)) and symmetric (S(0)) modes.

  16. Silicon Light: a European FP7 project aiming at high efficiency thin film silicon solar cells on foil. Monolithic series interconnection of flexible thin-film PV devices

    Energy Technology Data Exchange (ETDEWEB)

    Soppe, W. [ECN Solar Energy, P.O. Box 1, 1755 ZG Petten (Netherlands); Haug, F.J. [Ecole Polytechnique Federale de Lausanne EPFL, Photovoltaics and Thin Film Electronics Laboratory, Rue A.-L. Breguet 2, 2000 Neuchatel (Switzerland); Couty, P. [VHFTechnologies SA, Rue Edouard-Verdan 2, CH-1400 Yverdon-les-Bains (Switzerland); Duchamp, M. [Technical University of Denmark, Center for Electron Nanoscopy, DK-2800 Kongens Lyngby (Denmark); Schipper, W. [Nanoptics GmbH, Innungstr.5, 21244 Buchholz (Germany); Krc, J. [University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, SI-1000 Ljubljana (Slovenia); Sanchez, G. [Universidad Politecnica de Valencia, I.U.I. Centro de Tecnologia Nanofotonica, 46022 Valencia (Spain); Leitner, K. [Umicore Thin Film Products AG, Balzers (Liechtenstein); Wang, Q. [Shanghai Jiaotong University, Research Institute of Micro/Nanometer Science and Technology, 800 Dongchuan Road, Min Hang, 200240 Shanghai (China)

    2011-09-15

    Silicon-Light is a European FP7 project, which started January 1st, 2010 and aims at development of low cost, high-efficiency thin film silicon solar cells on foil. Three main routes are explored to achieve these goals: (a) advanced light trapping by implementing nanotexturization through UV Nano Imprinting Lithography (UV-NIL); (b) growth of crack-free silicon absorber layers on highly textured substrates; (c) development of new TCOs which should combine the best properties of presently available materials like ITO and AZO. The paper presents the midterm status of the project results, showing model calculations of ideal nanotextures for light trapping in thin film silicon solar cells; the fabrication of masters and the replication and roll-to-roll fabrication of these nanotextures. Further, results on ITO variants with improved work function are presented. Finally, the status of cell fabrication on foils with nanotexture is shown. Microcrystalline and amorphous silicon single junction cells with stable efficiencies with more than 8% have been made, paving the way towards a-Si/{mu}c-Si tandem cells with more than 11% efficiency.

  17. Determination of in situ speciation of manganese in treated acid mine drainage water by using multiple diffusive gradients in thin films devices

    Energy Technology Data Exchange (ETDEWEB)

    Lopes F de Oliveira, Rodrigo; Pedrobom, Jorge H. [Centro de Estudos Ambientais - CEA, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil); Menegário, Amauri A., E-mail: amenega@rc.unesp.br [Centro de Estudos Ambientais - CEA, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil); Domingos, Roberto N. [Centro de Estudos Ambientais - CEA, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil); Py, Delcy A. [INB - Indústrias Nucleares do Brasil, Estrada Poços – Andradas Km 20,6, CEP 37780-000 Caldas, MG (Brazil); Kiang, Chang Hung [Laboratório de Estudos de Bacias - LEBAC, Instituto de Geociências e Ciências Exatas - IGCE, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil)

    2013-10-17

    Graphical abstract: -- Highlights: •In situ speciation of Mn by using multiple DGT devices was evaluated. •Chelex resin, DE81 and P81 membranes were used as binding phases in the DGT devices. •The proposed approach was applied to analyze treated acid mine drainage. •Good results were found for speciation of Mn in site containing <40 mg Ca L{sup −1}. DGT speciation were in agreement with speciation by software and by on site SPE. -- Abstract: Acid mine drainage (AMD) is a serious environmental problem that creates acidic solution with high Mn concentrations. The speciation of residual Mn from AMD after an active treatment involving the addition of a neutralizing agent can reliably evaluate the treatment efficiency and provide knowledge of the Mn species being inputted into the environment. The aim of this study was to evaluate the in situ lability and speciation of Mn using the diffusive gradients in thin films (DGT) technique with treated drainage water from a uranium mine (TAMD). DGT devices with different binding phases (Chelex-100 and P81 and DE81membranes) were used to perform the in situ speciation of Mn. A comparison of the results from deploying DGT in the laboratory and in situ shows that the speciation of Mn in TAMD should be performed in situ. Linear deployment curves (from in situ experiments) indicate that the DGT device containing the Chelex-100 binding phase can be used to evaluate Mn lability in TAMD. The labile Mn fraction (from in situ measurements) obtained using the device containing the Chelex-100 resin ranged from 63 to 81% of the total Mn concentration and, when compared to the speciation obtained using the CHEAQS software, indicated that this device was capable of uptaking the free Mn{sup 2+} and a portion of the MnSO{sub 4(aq)}. The values obtained using the DGT technique were compared to those from on site solid phase extraction, and a good agreement was found between the results. The amount of negative Mn species sampled by DE81

  18. Determination of in situ speciation of manganese in treated acid mine drainage water by using multiple diffusive gradients in thin films devices.

    Science.gov (United States)

    de Oliveira, Rodrigo Lopes F; Pedrobom, Jorge H; Menegário, Amauri A; Domingos, Roberto N; Py Júnior, Delcy A; Kiang, Chang Hung

    2013-10-17

    Acid mine drainage (AMD) is a serious environmental problem that creates acidic solution with high Mn concentrations. The speciation of residual Mn from AMD after an active treatment involving the addition of a neutralizing agent can reliably evaluate the treatment efficiency and provide knowledge of the Mn species being inputted into the environment. The aim of this study was to evaluate the in situ lability and speciation of Mn using the diffusive gradients in thin films (DGT) technique with treated drainage water from a uranium mine (TAMD). DGT devices with different binding phases (Chelex-100 and P81 and DE81 membranes) were used to perform the in situ speciation of Mn. A comparison of the results from deploying DGT in the laboratory and in situ shows that the speciation of Mn in TAMD should be performed in situ. Linear deployment curves (from in situ experiments) indicate that the DGT device containing the Chelex-100 binding phase can be used to evaluate Mn lability in TAMD. The labile Mn fraction (from in situ measurements) obtained using the device containing the Chelex-100 resin ranged from 63 to 81% of the total Mn concentration and, when compared to the speciation obtained using the CHEAQS software, indicated that this device was capable of uptaking the free Mn(2+) and a portion of the MnSO4(aq). The values obtained using the DGT technique were compared to those from on site solid phase extraction, and a good agreement was found between the results. The amount of negative Mn species sampled by DE81 device was insignificant (speciation obtained using the CHEAQS software indicated that the concentrations of positive Mn species were underestimated for sites with relatively high Ca concentrations (>150 mg L(-1)), which take place due to the saturation of binding sites in the P81 membrane.

  19. New Copolymers Containing Charge Carriers for Organic Devices with ITO Films Treated by UV-Ozone Using High Intensity Discharge Lamp

    Directory of Open Access Journals (Sweden)

    Emerson Roberto SANTOS

    2009-02-01

    Full Text Available For electroluminescent devices new copolymers were synthesized using a Suzuki cross-coupling reaction based on monomers (fluorine-alt-phenylene in conjugation with quinoline-alt-phenylene units. They were characterized by 1H NMR, 13C NMR and FTIR. TGA measurements indicated that the copolymers have good thermal properties and no weight loss was observed up to 250 °C. The UV-Vis spectra were characterized by absorptions from the fluorene-alt-phenylene and quinoline-alt-phenylene segments in the backbone, while their photoluminescence (PL spectra dominated by emissions from the fluorene excimer. For devices assembly ITO films were treated using a High Intensity Discharge Lamp (HPMVL without outer bulb presenting high ozone concentration than that conventional germicidal lamp. The device with ITO treated revealed significant decrease of threshold voltage (or turn-on voltage compared by untreated with I-V curves. This decrease can be related by water and carbon dioxide extracted on surface after UV-Ozone treatment revealed by DRIFT measurements.

  20. Effects of thermal annealing of W/SiO2 multilayer Bragg reflectors on resonance characteristics of film bulk acoustic resonator devices with cobalt electrodes

    Science.gov (United States)

    Yim, Munhyuk; Kim, Dong-Hyun; Chai, Dongkyu; Yoon, Giwan

    2004-05-01

    In this article, we present the thermal annealing effects of the W/SiO2 multilayer reflectors in ZnO-based film bulk acoustic resonator (FBAR) devices with cobalt (Co) electrodes in comparison with those with aluminum (Al) electrodes. Various thermal annealing conditions have been implemented on the W/SiO2 multilayer reflectors formed on p-type (100) silicon substrates. The resonance characteristics could be significantly improved due to the thermal annealing and were observed to depend strongly on the annealing conditions applied to the reflectors. Particularly, the FBAR devices with the W/SiO2 multilayer reflectors annealed at 400 °C/30 min have shown superior resonance characteristics in terms of return loss and quality factor. In addition, the use of Co electrodes has resulted in the further improvement of the resonance characteristics as compared with the Al electrodes. As a result, the combined use of both the thermal annealing and Co electrodes seems very useful to more effectively improve the resonance characteristics of the FBAR devices with the W/SiO2 multilayer reflectors. .