Quantitative determination of element distributions in silicon based thin film solar cells using SNMS

The determination of elemental distributions in thin film solar cells based on amorphous silicon using electron beam SNMS is possible by quantifying the measured ion intensities. The relative sensitivity factors (RSFs) for all elements measured have to be known. The RSFs have been determined experimentally using implantation and bulk standards with known concentrations of the interesting elements. The measured RSFs have been compared with calculated RSFs. The model used for the calculation of the RSFs takes into account the probability for electron impact ionization and the dwell time of the neutrals inside the postionization region. The comparison between measured and calculated RSF shows, that this model is capable to explain the RSFs for most elements. Differences between calculated and measured values can be explained by the formation of hydride and fluoride molecules (in case of H and F) and influences of the angular distribution of the sputtered neutrals in case of Al. The experimentally determined RSFs have been used for a quantification of depth profiles of the i-, buffer-, p- and front contact layers of a-Si solar cells.     

Dichroism of (CH3NH3)2CdCl4 in the farinfrared

The dielectric constant of (CH₃NH₃)₂ CdCl₄ has been measured as a function of temperature in the submillimeter range. Freshly grown samples with a wide domain structure at room temperature show a pronounced dichroism in this spectral range which is caused by the orientation of the molecules in the room temperature orthorhombic phase and their response to the electromagnetic wave.     

Radio-frequency annealing effects in amorphous Fe40Ni40B20

The influence of radio frequency (rf) magnetic fields on the properties of amorphous Fe₄₀Ni₄₀B₂₀ was studied using Mössbauer spectroscopy. The measurements were performed with frequencies of 67 and 53 MHz and rf field intensity in the range of 1 to 12 Oe. The narrowing of the hyperfine spectra due to the rf field and the formation of rf sidebands were observed. The effect of instability and crystallization of the amorphous metal enhanced by the rf field at temperatures much lower than the crystallization temperature was observed.     

Some aspects of element distribution inBetula alba, a contribution to representative sampling of terrestrial plants for multi-element analysis

Summary The leaves of six differently aged birch trees (Betula alba), growing under slightly varying soil conditions, were collected representatively. The elements Ca, K, Mg and Zn were determined by different analytical methods (AAS and AES/ICP). The data sets obtained were in good agreeent with each other. The biological variances of Al, Ba, Ca, Cu, Fe, K, Mg, P and Zn between leaves of different trees were less than 30%, with the exception of phosphorus (38%). Ca, K, Mg, Mn and Zn show an increase of between 50%–70% depending on the height of the trees. The developed sampling procedure (5–10 trees per ecosystem) can be adapted to produce a representative sampling design on population level.

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Einige Aspekte der Elementverteilung inBetula alba, ein Beitrag zur repräsentativen Probenahme von terrestrischen Pflanzen für die Multielement-Analyse

     

Kinetic study of the heterogeneous Si/H system under low-pressure plasma conditions by means of mass spectrometry

The kinetics of the silicon/hydrogen low-pressure discharge system have been measured using a flow technique and mass spectrometry. Results show that at long residence times the system operates under a partial chemical equilibrium even though it is not at thermodynamic equilibrium. The present work indicates that the decisive parameter controlling the structural properties of the deposit (i.e., the formation of either amorphous or microcrystalline silicon) is the departure of the system from the partial chemical equilibrium.     

Synthesis of melanervin from melaleuca quinquenervia,the first naturally occurring compound with a triphenylmethane structure

Melanervin from Melaleuca quinquenervia, the first naturally occurring compound with a triphenylmethane structure, has been synthesized and its structure thereby confirmed.