Stability of hydrogenated nanocrystalline silicon thin-film transistors

Hydrogenated nanocrystalline silicon thin-films were obtained by catalytic chemical vapour deposition at low substrate temperatures (150°C) and high deposition rates (10 Å/s). These films, with crystalline fractions over 90%, were incorporated as the active layers of bottom-gate thin-film transistors. The initial field-effect mobilities of these devices were over 0.5 cm 2/V s and the threshold voltages lower than 4 V. In this work, we report on the enhanced stability of these devices under prolonged times of gate bias stress compared to amorphous silicon thin-film transistors. Hence, they are promising candidates to be considered in the future for applications such as flat-panel displays.

Compositional influence on the electrical performance of zinc indium tin oxide transparent thin-film transistors

In this work, zinc indium tin oxide layers with different compositions are used as the active layer of thin film transistors. This multicomponent transparent conductive oxide is gaining great interest due to its reduced content of the scarce indium element. Experimental data indicate that the incorporation of zinc promotes the creation of oxygen vacancies. In thin-film transistors this effect leads to a higher threshold voltage values. The field-effect mobility is also strongly degraded, probably due to coulomb scattering by ionized defects. A post deposition annealing in air reduces the density of oxygen vacancies and improves the fieldeffect mobility by orders of magnitude. Finally, the electrical characteristics of the fabricated thin-film transistors have been analyzed to estimate the density of states in the gap of the active layers. These measurements reveal a clear peak located at 0.3 eV from the conduction band edge that could be attributed to oxygen vacancies.

Amorphous silicon thin film solar cells deposited entirely by Hot-Wire Chemical Vapour Deposition at low temperature (<150 ºC)

Amorphous silicon n-i-p solar cells have been fabricated entirely by Hot-Wire Chemical Vapour Deposition (HW-CVD) at low process temperature < 150 °C. A textured-Ag/ZnO back reflector deposited on Corning 1737F by rf magnetron sputtering was used as the substrate. Doped layers with very good conductivity and a very less defective intrinsic a-Si:H layer were used for the cell fabrication. A double n-layer (μc-Si:H/a-Si:H) and μc-Si:H p-layer were used for the cell. In this paper, we report the characterization of these layers and the integration of these layers in a solar cell fabricated at low temperature. An initial efficiency of 4.62% has been achieved for the n-i-p cell deposited at temperatures below 150 °C over glass/Ag/ZnO textured back reflector.

Electronic transport in low temperature nanocrystalline silicon thin-film transistors obtained by Hot-Wire CVD

Hydrogenated nanocrystalline silicon (nc-Si:H) obtained by hot-wire chemical vapour deposition (HWCVD) at low substrate temperature (150 °C) has been incorporated as the active layer in bottom-gate thin-film transistors (TFTs). These devices were electrically characterised by measuring in vacuum the output and transfer characteristics for different temperatures. The field-effect mobility showed a thermally activated behaviour which could be attributed to carrier trapping at the band tails, as in hydrogenated amorphous silicon (a-Si:H), and potential barriers for the electronic transport. Trapped charge at the interfaces of the columns, which are typical in nc-Si:H, would account for these barriers. By using the Levinson technique, the quality of the material at the column boundaries could be studied. Finally, these results were interpreted according to the particular microstructure of nc-Si:H.

Microcrystalline silicon thin film transistors obtained by Hot-Wire CVD

Polysilicon thin film transistors (TFT) are of great interest in the field of large area microelectronics, especially because of their application as active elements in flat panel displays. Different deposition techniques are in tough competition with the objective to obtain device-quality polysilicon thin films at low temperature. In this paper we present the preliminary results obtained with the fabrication of TFT deposited by hot-wire chemical vapor deposition (HWCVD). Some results concerned with the structural characterization of the material and electrical performance of the device are presented.

Thin Film Transistors obtained by Hot-Wire CVD

Hydrogenated microcrystalline silicon films obtained at low temperature (150-280°C) by hot wire chemical vapour deposition at two different process pressures were measured by Raman spectroscopy, X-ray diffraction (XRD) spectroscopy and photothermal deflection spectroscopy (PDS). A crystalline fraction >90% with a subgap optical absortion 10 cm -1 at 0.8 eV were obtained in films deposited at growth rates >0.8 nm/s. These films were incorporated in n-channel thin film transistors and their electrical properties were measured. The saturation mobility was 0.72 ± 0.05 cm 2/ V s and the threshold voltage around 0.2 eV. The dependence of their conductance activation energies on gate voltages were related to the properties of the material.

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Recension

Hollywood Films in the Non-Western World: What Are the Criteria Followed by the Chinese Government When Choosing Hollywood Film Imports?

This dissertation argues that the Government of the People’s Republic of China, when it made the decision to import a quota of Hollywood films in 1994 to revive the failing domestic film industry, had different possible criteria in mind. This project has studied four of them: first, importing films that gave a negative image of the United States; second, importing films that featured Chinese talent or themes; third, importing films that were box office hits in the United States; and fourth, importing films with a strong technological innovation ingredient. In order to find out the most important criteria for the Chinese Government, this dissertation offers a dataset that analyzes a population of 262 Hollywood films released in the PRC between 1994 and 2010. For each unit, a method has been developed to compile data that will determine whether the film reflects any of the four criteria, and findings in the form of yearly percentages have been drawn. Results show that, out of the four studied criteria, the two predominant reasons for China to import films were technological innovation and box office hits. This tells us that, at this point, the Chinese Government shows more interest in obtaining big revenues and learning from technically innovative American films than in delivering underlying political messages. This dissertation contributes to the existing literature by analyzing the content of all the films imported by China between 1994 and 2010, while integrating in the analysis variables based on the existing knowledge.

The Transnational Zombie: Postcolonial Memory and Rage in the Recent European Horror Film

An ever increasing number of films, books, and scholarly works dealing with the undead have appeared in the last decade, making the zombie the very incarnation of American popular culture on a global scale. In this chapter I show that the zombie is also a surprisingly complex sign for transnational movement and multidirectional cultural flow. While the zombie may appear as the very epitome of American cultural production and influence, a mindless movie monster born of a vapid stream of Hollywood B-horror, the zombie has a rich transnational history and an eloquent figurative resonance that have fed into its current ubiquity as cultural sign. This chapter reviews that history and then examines some of the ways that the zombie figure has traveled between the Caribbean, where it emerged, the United States, where it was translated into a film device of startling pathos and horror, and Europe, to which it owes some of its most interesting recent innovations.

Effect of partial-thickness tear on loading capacities of the supraspinatus tendon: a finite element analysis.

Partial-thickness tears of the supraspinatus tendon frequently occur at its insertion on the greater tubercule of the humerus, causing pain and reduced strength and range of motion. The goal of this work was to quantify the loss of loading capacity due to tendon tears at the insertion area. A finite element model of the supraspinatus tendon was developed using in vivo magnetic resonance images data. The tendon was represented by an anisotropic hyperelastic constitutive law identified with experimental measurements. A failure criterion was proposed and calibrated with experimental data. A partial-thickness tear was gradually increased, starting from the deep articular-sided fibres. For different values of tendon tear thickness, the tendon was mechanically loaded up to failure. The numerical model predicted a loss in loading capacity of the tendon as the tear thickness progressed. Tendon failure was more likely when the tendon tear exceeded 20%. The predictions of the model were consistent with experimental studies. Partial-thickness tears below 40% tear are sufficiently stable to persist physiotherapeutic exercises. Above 60% tear surgery should be considered to restore shoulder strength.

La controverse avant le film : quelle politique pour Good Night, And Good Luck ?

This article aims to explain how newspapers commented on the movie Good Night, and Good Luck before its release. The media coverage anticipated George Clooney's film as a partisan attack launched against George W. Bush's policy since 9/11. Clooney advocates another reading: the historic confrontation between journalist Edward Murrow and Senator Joseph McCarty permits to reflect on the crucial role that the media play for democracy. Such reflection tries to prevent the dividing of the public sphere into antagonistic camps opposing "friends" to "foes," a division that undermines the possibility of a true pluralism. Our socio-semiotic analysis will focus on the critical work accomplished by the media, and on the way that work determines the collective meaning of a cultural object. Simultaneously, we will discuss the necessary conditions for pluralism in a public sphere.

Glenohumeral interposition of rotator cuff stumps: a rare complication of traumatic rotator cuff tear

Abstract The present report describes a case where typical findings of traumatic glenohumeral interposition of rotator cuff stumps were surgically confirmed. This condition is a rare complication of shoulder trauma. Generally, it occurs in high-energy trauma, frequently in association with glenohumeral joint dislocation. Radiography demonstrated increased joint space, internal rotation of the humerus and coracoid process fracture. In addition to the mentioned findings, magnetic resonance imaging showed massive rotator cuff tear with interposition of the supraspinatus, infraspinatus and subscapularis stumps within the glenohumeral joint. Surgical treatment was performed confirming the injury and the rotator cuff stumps interposition. It is important that radiologists and orthopedic surgeons become familiar with this entity which, because of its rarity, might be neglected in cases of shoulder trauma.