The aim of the TeleRisk Project on labour relations and professional risks within the context of teleworking in Portugal – supported by IDICT – Institute for Development and Inspection of Working Conditions (Ministry of Labour), is to study the practices and forms of teleworking in the manufacturing sectors in Portugal. The project chose also the software industry as a reference sector, even though it does not intend to exclude from the study any other sector of activity or the so-called “hybrid” forms of work. However, the latter must have some of the characteristics of telework. The project thus takes into account the so-called “traditional” sectors of activity, namely textile and machinery and metal engineering (machinery and equipment), not usually associated to this type of work. However, telework could include, in the so-called “traditional” sectors, other variations that are not found in technologically based sectors. One of the evaluation methods for the dynamics associated to telework consisted in carrying out surveys by means of questionnaires, aimed at employers in the sectors analysed. This paper presents some of the results of those surveys. It is important to mention that, being a preliminary analysis, it means that it does not pretend to have exhausted all the issues in the survey, but has meant that it shows the bigger tendencies, in terms of teleworking practices, of the Portuguese industry.

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Position sensitive detectors (PSD) using hydrogenated amorphous silicon as the active layer have been widely proposed either with the p-i-n or the Schottky structure. In this case, the devices are tailored to respond to light in the range 620-650 nm. Little is known about the use of silicon carbide active layers in such devices, which is important when the detected light is in the blue region of the light spectrum. In this paper we present for the first time the electro-optical properties of the a-Six:C1-x:H/Pd and p-ic-n PSD, using a-Six:C1-x:H layers deposited by plasma enhanced chemical vapour deposition (PECVD). These sensors are able to distinguish the wavelength of the impinging visible radiation (from red to blue light). In addition, the sensors respond to light intensities as lower as 1 × 10-6 W cm-2 with a resolution better than 0.04 mm and a linearity between ±0.12% and ±0.8%. © 2002 Elsevier Science B.V. All rights reserved.

In this work, we report the electro-optical properties exhibited by ZnO:A1 thin films deposited by r.f. magnetron sputtering. The effect of the deposition parameters on the properties of the films were studied with the aim to determine the most suitable deposition conditions to obtain ZnO:Al thin films with a low resistivity and high transmittance, characteristics required for applications on optoelectronic devices. After annealing, the ZnO:Al thin films present a low resistivity (6.25 × 10-3 Ωcm) and a high transmittance (90%) when produced with a deposition pressure of 1.6 × 10-2 mbar and r.f. power of 150W. © 2002 Elsevier Science Ltd. All rights reserved.

The room temperature ozone sensing properties of polycrystalline undoped zinc oxide (ZnO) thin films have been investigated. ZnO thin films have been produced by the d.c. and r.f. magnetron sputtering technique as well as with spray pyrolysis with a variety of parameters. The as-grown films were brought to a high conducting state through a reversible photoreduction process by UV light exposure and were subsequently exposed to ozone resulting in a strong resistivity increase caused by re-oxidation. The magnitude of the effect was largest for the sputtered films, which exhibited resistivity changes of more than 8 orders of magnitude, whereas films deposited by spray pyrolysis showed changes of less than 3 orders of magnitude. XRD and AFM analysis of the films revealed that all films were microcrystalline. The film texture, however, was strongly related to the growth technique and the parameters used. Best results were achieved with r.f.-sputtered films, which have been deposited at high total pressures. These films exhibited a sensor response of 1.2 × 108. © 2002 Elsevier Science B.V. All rights reserved.

In this work we studied the influence of hydrogen dilution, rf power, and the filament and substrate temperatures on the electro-optical properties and composition of a-Si:H films produced by hot wire plasma assisted technique. The a-Si:H films were produced on Mylar substrates with growth rate of up to 37 Å/s, ημτ product of 1.6 × 10-7 cm2/V, photoconductivity to dark conductivity ratio of 1 × 104 (at AM1.5 radiation), and a dark conductivity of about 10-10 (Ω cm)-1 for substrate temperature of 130 °C, hydrogen dilution of 99%, filament temperature of 1700 °C, and rf power of 100 W. © 2002 Elsevier Science B.V. All rights reserved.

The most common techniques used to produce ZnO thin films are the spray pyrolysis and the magnetron sputtering techniques, low and high cost processes respectively. The aim of this work is to compare the properties of the films produced by these two techniques. The predominant difference observed was on the morphological properties. The films produced by spray pyrolysis have a rougher surface than the ones obtained by sputtering. Also the effect of the thermal annealing treatment is much more prononnced for the ZnO thin films produced by spray pyrolysis. After heat treatment films exhibit similar electrical properties and their application to optoelectronic devices is demonstrated.

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In this work we present the results of a study on the uniformity of ZnO thin films produced by spray pyrolysis. The properties of the thin films depend essentially on the carrier gas pressure and gas flow used. The best films for optoelectronic applications were obtained with a carrier gas pressure of 2 bar and solution flow of 37 ml/min. The velocity of the nozzle affects essentially the uniformity of the ZnO thin films. However this important characteristic of the large area thin films is independent of the nature (doped and undoped) of the thin film and exhibits a high dependence on the variation of the temperature along the substrate. © 2001 Materials Research Society.

The performances of amorphous and nano-crystalline porous silicon thin films as gas detector are pioneer reported in this work. The films were produced by the hot wire chemical vapour deposition (HW-CVD). These films present a porous like-structure, which is due to the uncompensated bonds and oxidise easily in the presence of air. This behaviour is a problem when the films are used for solar cells or thin film transistors. For as gas detectors, the oxidation is a benefit, since the CO, H2 or O2 molecules replace the OH adsorbed group. In the present study we observe the behaviour of amorphous and nano-crystalline porous silicon thin films under the presence of ethanol, at room temperature. The data obtained reveal a change in the current values recorded by more than three orders of magnitude, depending on the film preparation condition. This current behaviour is due to the adsorption of the OH chemical group by the Si uncompensated bonds as can be observed in the infrared spectra. Besides that, the current response and its recover time are done in few seconds.

Flexible large area thin film position sensitive detectors based on amorphous silicon technology were prepared on polyimide substrates using the conventional plasma enhanced chemical vapor deposition technique. The sensors were characterized by spectral response, illuminated I-V characteristics position detectability measurements and atomic force microscopy. The obtained one-dimensional position sensors, 5-mm wide and 60-mm long, presented a maximum spectral response at 600 nm, an open circuit voltage of 0.6 V and a position detectability with a correlation of 0.9989 associated to a S.D. of 1×10-2, comparable to those produced on glass substrates.

Coal fly ashes produced by an extinguished power plant in the north of Portugal have been melted with addition of CaCO3 and Na2CO3 to obtain glasses. One of the formulated compositions was selected for further studies and it was possible to manufacture glass-ceramics by crystallizing the parent glass through adequate time-temperature schedules. The macroscopic appearance, microstructure, mechanical, thermal and chemical properties indicated that these materials are quite attractive for cladding applications, exhibiting in some cases better performances than the conventional ceramic tiles.