This study addresses the electrical and optical properties as well as the surface structure after wet-chemical etching of mid-frequency magnetron sputtered aluminium doped zinc oxide (ZnO:Al) films on glass substrates from rotatable ceramic targets. Etching of an as-deposited ZnO:Al film in acid leads to rough surfaces with various feature sizes. The influence of working pressure and substrate temperature on the surface topography after etching was investigated. It was found that the growth model which Kluth et al. applied to films sputtered in radio frequency mode from planar ceramic target can be transferred to film growth from tube target. Furthermore, the influence of Ar gas flow and discharge power on the film properties was investigated. We achieved low resistivity of about 5.4×10−4 Ω·cm at high growth rates of 120 nm·m/min. Finally, surface textured ZnO:Al films were applied as substrates for microcrystalline silicon solar cells and high efficiencies of up to 8.49% were obtained.

Aluminum-doped zinc oxide (AZO) films were prepared by in-line direct current (dc) magnetron sputtering on glass substrates. Four types of ceramic targets with 0.5 wt.% or 1 wt.% of aluminum oxide and different preparation methods, namely normal sintered, soft sintered and hot pressed, were employed. The influence of different target manufacturing processes, aluminum concentration and sputtering conditions on AZO films were investigated. Depending on the type of targets and deposition conditions, highly transparent films with low resistivity values in the range of 3.6-11 x 10(-4) Omega cm were obtained. The etching behaviour in hydrochloric acid and the resulting light scattering properties of the AZO films were strongly influenced by the choice of the target and the deposition conditions. The most favourable films have been successfuily applied in thin film solar cells with 1.1-mu m microcrystalline silicon absorber layer leading to an initial efficiency of 7.8%. (C) 2007 Elsevier B.V. All rights reserved.

A linear anode layer ion source was newly installed in a vertical in-line system. Argon and oxygen ions are generated to treat the HCl textured ZnO:Al films which are used as the transparent front contact in silicon thin film solar cells. The ion bombardment can modify the topography of the rough films which further give the chance to improve the current of the solar cells. The surfaces of the ZnO:Al films are eroded by the ions, and the etch rate is almost linearly proportional to the discharge power of the ion source. The resistivity of the treated films is not changed obviously by the argon ions. The textured ZnO:Al films are smoothened by the ion beam treatment, and the haze is slightly decreased. So far, microcrystalline silicon solar cells on the ion beam treated ZnO:Al films have lower efficiency and higher open-circuit voltage as compared to the untreated films. This might be caused by the fact that the silicon p-layer on treated ZnO:Al films have lower crystalline fraction.

Aluminium-doped zinc oxide films were deposited on glass substrates at high rates by reactive mid-frequency sputtering. The in-line sputter system allows oxygen influx along the middle and sides of a dual-cathode system. The effect of varying the oxygen flow from the sides on the electrical and optical properties together with the surface morphology after wet chemical etching was investigated. Increasing the amount of oxygen flow from the sides improved the resistivity profile of static prints and gave highly conductive and transparent films in dynamic deposition mode. The etched films developed rough surface textures with effective light scattering that could be controlled by the oxygen balance between the middle and sides. Optimally textured films were used as front contacts in 1 cm(2) single junction microcrystal line solar cells yielding an initial efficiency of 8.4%. The improvement in light trapping led to short circuit densities higher than that of the reference solar cells. (C) 2007 Elsevier B.V. All rights reserved.

Aluminum doped zinc oxide (ZnO:Al) films were prepared by high rate magnetron sputter deposition either in reactive or non reactive mode from metallic or ceramic targets, respectively. These two different sputtering modes were compared in view on industrial scale production. We characterized the electrical properties in dependence on deposition parameters and growth rate. The deposition pressure dependence and statically deposited ZnO:Al films revealed a strong influence of high energy ion bombardment, which reduces conductivity and thus has to be avoided by appropriate deposition conditions. Finally, texture-etched ZnO:Al films were successfully applied as front contacts for silicon thin film solar cells. An initial aperture area (676 cm2) module efficiency of nearly 10 % was achieved for a-Si:H/μc-Si:H tandem modules for both ZnO:Al preparation processes.

We developed microcrystalline silicon (μc-Si:H) thin film solar modules on textured ZnO-coated glass. The single junction (p–i–n) cell structure was prepared by plasma-enhanced chemical vapour deposition (PECVD) at substrate temperatures below 250°C. Front ZnO and back contacts were prepared by sputtering. A process for the monolithic series connection of μc-Si:H cells by laser scribing was developed. These microcrystalline p–i–n modules showed aperture area efficiencies up to 8.3% and 7.3% on aperture areas of 64 and 676cm2, respectively. The temperature coefficient of the efficiency was −0.4%/K.

We succeeded in preparing a-Si:H//spl mu/c-Si:H solar cells on 30/spl times/30 cm/sup 2/ substrate size using high rate 13.56 MHz PECVD processes. Stable cell efficiencies up to 11.2% were achieved on textured ZnO as front TCO. First solar modules were realised by applying an industrially established technology for patterning and back contact preparation. These modules showed initial aperture area efficiencies (689 cm/sup 2/) up to 9.7% using SnO/sub 2/ coated glass substrates. In parallel, a new process technology for the development of a-Si:H//spl mu/c-Si:H solar modules on glass started operation at the Institute of Photovoltaics. On 30/spl times/30 cm/sup 2/ substrate size initial aperture area module efficiencies of 10.1% were demonstrated by using texture-etched ZnO:Al coated glass substrates.

Magnetron sputtered ZnO:Al films are promising candidates as front electrode in a variety of opto-electronic devices. Here we report on efforts to obtain highly conductive and transparent ZnO:Al films using different deposition conditions for RF, DC and MF (mid frequency) sputtering. Investigations were made to see the effect of target doping concentration (TDC), film thickness, sputter pressure and deposition temperature. RF sputtering from ceramic targets yields low resistivities between 3 and 5×10−4 Ω cm for target doping concentrations between 4 and 0.5%. With decreasing TDC to 0.5% carrier mobilities up to 44 cm2/Vs were obtained, accompanied by the extension of the region of high transmission to the near infrared, due to a reduction in free carrier absorption and corresponding shift in plasma wavelength. DC and MF sputtering from metallic targets yielded similar low resistivities at deposition rates up to 200 nm/min. An analysis of mobility (μ) data of all films as function of the corresponding carrier densities (N) showed that the μ–N values obtained in this study are in the vicinity to limits suggested in the literature.

ZnO films prepared by magnetron sputtering on glass substrates and textured by post-deposition chemical etching are applied as substrates for p–i–n solar cells. Using both rf and dc sputtering, similar surface textures can be achieved upon etching. Excellent light trapping is demonstrated by high quantum efficiencies at long wavelengths for microcrystalline silicon solar cells. Applying an optimized microcrystalline/amorphous p-layer design, stacked solar cells with amorphous silicon top cells yield similarly high stabilized efficiencies on ZnO as on state-of-the-art SnO2 (9.2% for a-Si/a-Si). The efficiencies are significantly higher than on SnO2-coated float glass as used for module production.

Thoriated electrodes are used in TIG welding. TIG welders, along with persons who grind thoriated electrodes and persons located near relevant welding and grinding sites, might be at risk of thorium intake. The isotopes of radiological relevance are 232Th, 230Th, and 228Th. The studies described in the literature do not provide a consistent picture of the actual hazards, and changes in European and German radiological protection laws have now made it necessary to determine the risks. To accomplish this, a field test was conducted under real working conditions in 26 different welding shops. The airborne activity generated through welding, and through grinding of electrodes, was measured using personal air samplers. Stationary samplers were also used. The filters' samples were evaluated by means of direct alpha spectrometry with proportional counting and by means of gamma spectrometry following neutron activation. The results clearly showed that considerable intake can occur during both alternating-current welding and electrode grinding, if no suction systems are used. The range of 232Th intakes to welders were estimated from 0.1 Bq y(-1) to 144 Bq y(-1) during welding and from 0.02 Bq y(-1) to 30.2 Bq y(-1) during grinding. In 6 of the 26 cases the recent annual limit on intake derived from the most recent ICRP publications was exceeded--in the worst case it was exceeded by a factor of 10--if it is assumed that the persons studied were not exposed workers (not routinely monitored for radiation exposure). When the significantly more restrictive German limits are applied, the amounts by which the limits were exceeded were even greater. Because many qualified welders have very long careers, the risks can thus be considerable. The paper also discusses parameters that influence exposure, and it presents a catalogue of recommended measures for dosage reduction.

This paper proposes a fault diagnostic method for pump running conditions. The method is a combination of a process modeling and a classification procedure. The pump head and hydraulic losses in the pipe system are modeled by two equations. The values of the coefficients in the equations are determined from measurable output variables of the pump. Since the pump running conditions affect the coefficient values, they are detected by classifying those values. A multi-layer neural network is employed for the classification. Three running conditions of a drainage pump are clearly detected by this method. The accuracy of detection is improved by increasing the hidden layers and their units in the neural network.

In the past, there has been a wide divergence of opinions on the risk of burns from touching hot surfaces. This has been reflected in the information available for maximum surface temperatures, which have so far been laid down in standards. However, study results are now available which will allow substantiated maximum temperatures for hot surfaces to be laid down.

The knowledge that there is a risk of burning from touching hot surfaces is certainly nothing new. However, little progress has been made so far on the matter of the minimum surface temperature at which burning can be expected. Preparatory work on determining these threshold values has now been finished by the Berufsgenossenschaftlichen Institut fur Arbeitssicherheit (Occupational Safety Institute of Industrial Injuries Insurance Institutes). The figures are included in UVV "Hitze" (Accident Prevention Regulation on "Heat").

Reaction products corresponding to the transfer of one and several protons have been measured over a large angular range for incident energies of 380 MeV and 400 MeV in reactions of86Kr with88Sr,90Zr and92Mo. For transitions with smallQ-values (total kinetic energy loss TKEL≦10 MeV) the transfer probabilities are deduced. The magnitudes and slopes of these probabilities as function of the distance of closest approach between two nuclei are discussed. The results for single proton transfer are well described by tunneling, whereas the transfer of two and more nucleons into low lying states of the final nuclei seems to be influenced by intermediate transfer steps with larger TKEL. The data give the possibility to discuss the relation between deep-inelastic and quasi-elastic processes. The deep-inelastic data are analyzed successfully by including deformations, charge transfer and statistical fluctuations into the frictional model of Gross and Kalinowski.

In the preceding publication (see p. 1) the question arose of how to explain the longitudinal tears of the vertebral arteries at the departure of the posterior inferior cerebellar artery, that occur as origin of fatal subarachnoidal hemorrhage subsequent to blunt forces against the head. As the result of calculation of flow dynamics in a right-angled branching a curvature of the main vessel opposite to the flow in the branch develops. If the main vessel is unable to evade, the branch will be impressed into the main vessel in a piston-like manner. An experiment with silicon tubes succeeded to produce longitudinal tears resembling to those described by Krauland. Traumatic increase of pressure and stress of the vessels are considered the most likely cause of longitudinal ruptures of the basal arteries.