Articles you may be interested inThermal annealing effects on the structure and electrical properties of Al 2 O 3 gate dielectrics on fully depleted SiGe on insulator
In this work, a new type of short water vapor treatment of the interface between the p-and i-layer is presented. This novel treatment is performed under vacuum below 1 mbar for 5 min and considerably reduces the i-layer boron contamination in amorphous silicon (a-Si:H) p-i-n solar cells prepared in single-chamber reactors. A significant advantage is that the substrate with the p-layer can remain loaded in the reactor during this oxidation treatment. The high effectiveness of this treatment in reducing the boron cross-contamination is directly supported by secondary ion mass spectroscopy measurements, by tracing the boron concentration depth profile across the p-i interface and by quantum efficiency measurements of the deposited cells. By applying this water vapor treatment, 0.3-mm-thick a-Si:H p-i-n solar cells of 1 cm with high initial conversion efficiencies of 10.1% are 2 deposited in a commercial large-area (35=45 cm ) single-chamber PECVD KAI reactor and can clearly compete with cells 2 deposited in multi-chamber systems. Light soaking of these cells for 1200 h at 50 8C leads to stabilized efficiencies of 8.2%. The relative typical efficiency degradation of 20% of such 0.3-mm-thick single-junction cells demonstrates that this treatment does not affect the stability in a negative manner.
We have developed an electron lithography method, hot electron emission lithography, which is capable of printing integrated circuits with an exposure time of only a few seconds. The basic design and fabrication of the patterned electron emitting mask made by standard metal–oxide–semiconductor technology will be discussed, and its applicability in a simple 1:1 e-beam stepper will be demonstrated. Patterns with a minimum feature size of 160 nm have been printed successfully. Further improvements in resolution to 50 nm appear to be possible.
The chemical and microstructural properties of a surface have a strong influence on the growth mode and the morphology of a film evaporated onto this interface. Changes in the growth stress of thin titanium films, measured in situ by a cantilever beam technique, evaporated under UHV-conditions are used to monitor the chemical and microstructural properties of a substrate surface. The starting substrate film used in this study was a quasi single-crystalline TiO2-film (d=50 nm) prepared by reactive evaporation of titanium in an oxygen atmosphere and subsequent annealing (20 min, 400°C). The Ti-growth stress on this substrate is compressive up to monolayer coverage and tensile at higher film thickness, which is interpreted to indicate a strong interaction between TiO2 and the arriving Ti atoms at the interface during monolayer formation and strained (tensile) layer epitaxy at higher film thickness. In a second series of experiments the TiO2-film was covered with Al-overlayers of varying thickness. Due to oxygen interdiffusion from the TiO2-film an amorphous Al-oxide layer is formed at the interface eliminating the high degree of order of the substrate TiO2-film. On this amorphous substrate the stress vs. thickness curve of the Ti-film, in terms of our stress model, is interpreted to indicate island formation and growth of a polycrystalline Ti-film. At Al-layer thicknesses above about 3 nm the Al-interface becomes metallic. The structure of this Al-surface depends on the film thickness and substrate temperature during its deposition. During deposition of the first Ti-monolayer on metallic Al a large incremental tensile stress (up to 45 GPa) is measured. The magnitude of this tensile stress is closely related to the surface microstructure of the Al substrate. The surface roughness deduced from the tensile interface stress is compared with the surface roughness measured by AFM.For comparison, analogous experiments were made with Al2O3/Al substrate bilayers. The results of these experiments qualitatively agree with those on the TiO2/Al-substrate. The general shape of the stress vs. thickness curve is comparable, however quantitative differences are interpreted to be due to differences in the structure and/or chemical composition of the substrate Al-film.
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