On the formation of blisters in annealed hydrogenated a-Si layers

Differently hydrogenated radio frequency-sputtered a-Si layers have been studied by infrared (IR) spectroscopy as a function of the annealing time at 350 Celsius with the aim to get a deeper understanding of the origin of blisters previously observed by us in a-Si/a-Ge multilayers prepared under the same conditions as the ones applied to the present a-Si layers. The H content varied between 10.8 and 17.6 at.% as measured by elastic recoil detection analysis. IR spectroscopy showed that the concentration of the clustered (Si-H)n groups and of the (Si-H2)n (n ≥ 1) polymers increased at the expense of the Si-H mono-hydrides with increasing annealing time, suggesting that there is a corresponding increase of the volume of micro-voids whose walls are assumed from literature to be decorated by the clustered mono-hydride groups and polymers. At the same time, an increase in the size of surface blisters was observed. Also, with increasing annealing time, the total concentration of bonded H of any type decreases, indicating that H is partially released from its bonds to Si. It is argued that the H released from the (Si-H)n complexes and polymers at the microvoid surfaces form molecular H2 inside the voids, whose size increases upon annealing because of the thermal expansion of the H2 gas, eventually producing plastic surface deformation in the shape of blisters

Nanopattern formation in UV laser treated a-AlOx and nc-Al/AlOx layers

Hexagonal nanopatterns were fabricated in sputter deposited Al-oxide thin films by means of single UV laser pulses via a layer of self-assembled silica nanospheres. The hexagonal pattern was projected to the surface due to the focussing effect of the silica nanolenses enhancing the local impact of the pulse. As a result of the laser pulse large area ordered structure of nano-pits were formed in RF sputtered amorphous Al-oxide films, while nano-craters were created in DC sputter deposited layers that consist of Al nanocrystals embedded in amorphous matrix. The two different mechanisms governing the nanostructure formation in the a-AlOx and nc-Al/AlOx composite layers were revealed by Atomic Force Microscopy (AFM), cross-sectional Transmission Electron Microscopy (XTEM), spectroscopic ellipsometry and computer simulation

Refractive Index Variation of Magnetron-Sputtered a-Si1−xGex by “One-Sample Concept” Combinatory

Gradient a-Si1−xGex layers have been deposited by ”one-sample concept” combinatorial direct current (DC) magnetron sputtering onto one-inch-long Si slabs. Characterizations by electron microscopy, ion beam analysis and ellipsometry show that the layers are amorphous with a uniform thickness, small roughness and compositions from x = 0 to x = 1 changing linearly with the lateral position. By focused-beam mapping ellipsometry, we show that the optical constants also vary linearly with the lateral position, implying that the optical constants are linear functions of the composition. Both the refractive index and the extinction coefficient can be varied in a broad range for a large spectral region. The precise control and the knowledge of layer properties as a function of composition is of primary importance in many applications from solar cells to sensors

Az UV-B sugárzás hatása a kukorica fejlődésére = Effect of UV-B radiation on maize development

Az ózonréteg évtizedek óta tartó vékonyodása az UV-B sugárzás globális szinten történő megemelkedéséhez vezetett. Nemesítési programunkban ezért célul tűztük ki olyan beltenyésztett vonalak és hibridek nemesítését, melyek e negatív környezeti hatást jobban tolerálni tudják. Ugyanazon 10 eltérő tenyészidejű és különböző genetikai háttérbázissal rendelkező beltenyésztett vonalakat vizsgálva megállapítottuk, hogy a magasabb sugárzási szint a a kukorica leveleiben szignifikánsan magasabb össz-antocián termelést eredményezett. Mérési eredményeink igazolták, hogy vannak olyan anyagok, melyek antociántartalma eleve magas, így ezért a nagyobb UV-B sugárzásra kevésbé reagálnak, míg más típusok szignifikánsan magasabb össz-antocián termelésel reagálnak. A martonvásári levélmintáknál kipróbálásra került egy új, fluoreszcencia leképezési technikán alapuló módszer. Ennek segitségével a különböző stresszorok által okozott funkciócsökkenés képszerűen is megjelenithető. A speciális fitotron kamrában mértük a magasabb UV-B sugárzás fotoszintézisre gyakorolt hatását. Az itt kapott eredmények is igazolták egyes korai genotípusok érzékenységét, ami a netto fotoszintetikus aktivitásuk csökkenésében jelentkezett. Az antioxidáns enzimek aktivitásával kapcsolatos eredményeink is azt a megfigyelést támasztják alá, hogy ezek a korai, az UV-B sugárzásra érzékeny beltenyésztett vonalaknak a reaktív oxigénformákat elimináló képessége gyengébb, mint a későieké. | The ozone layer has become thinner in recent decades, leading to an increase in UV-B radiation on a global scale. One aim of our breeding programme is thus to develop inbred lines and hybrids capable of tolerating this negative environmental effect. Tests on ten inbred lines with diverse vegetation periods and genetic backgrounds revealed that a higher radiation level led to the production of a significantly higher quantity of total anthocyanin in maize leaves. The measurements proved that the initial anthocyanin content was higher in some genotypes, which thus had a milder response to higher UV-B radiation levels, while other types responded with a significant increase in total anthocyanin production. A new method based on the fluorescence imaging technique was tested on leaf samples taken in Martonvásár. This method allows the reduction in functioning ability caused by various stressors to be recorded before the damage is measurable by other means. The special phytotron chamber was used to determine the effect of higher UV-B radiation levels on photosynthesis. These measurements confirmed the sensitivity of certain early genotypes, revealed by a reduction in net photosynthetic activity. Measurements on the activity of antioxidant enzymes confirmed that early inbred lines sensitive to UV-B radiation were less able to eliminate reactive oxygen species than later genotypes