Margarita Kessler

Learn More
Presently, the PV industry is switching to the selective emitter design, where the phosphorus density is significantly reduced between the front metal fingers. Current diffusion models simply adjust the peak phosphorus density at the Si surface to match the measured profiles, and therefore they are unable to predict the necessary gas flows and the(More)
Future low-cost Si photovoltaics shall combine the high-efficiency potential of ultrathin monocrystalline Si films with the low cost per area of the Si-thin-film photovoltaics. The literature describes various techniques for fabricating ultrathin monocrystalline Si films with no need for sawing wafers. Layer transfer using epitaxy on porous Si and(More)
We present n-type silicon PERT (passivated emitter and rear totally diffused) solar cells with an Al<inf>2</inf>O<inf>3</inf>/SiN<inf>x</inf>-passivated BBr<inf>3</inf>-diffused back-junction emitter. The aluminum front side grid is evaporated in an industrial-type in-line evaporation system. The efficiency of the best 4 cm<sup>2</sup> solar cell is 19.6%,(More)
The main classes of human plasma lipids, free fatty acids, cholesterol, cholesterol esters, triglycerides and phosphatidylcholines were identified and quantified from samples of human plasma by field desorption mass spectrometry. A crude lipid extract was prepared from 50 microliters of human plasma and a 1-5% aliquot thereof was subjected directly to field(More)
We present emitter saturation current densities (J<inf>0E</inf>) of different types of BBr<inf>3</inf> furnace-diffused boron emitters for a range of different sheet resistances on planar an textured surfaces: (a) &#x201C;oxidized&#x201D; emitters with an extended drive-in phase under oxygen and (b) &#x201C;industrial&#x201D; emitters without such(More)
Effective control of diffused phosphorus profiles in crystalline silicon requires detailed understanding of the doping process. We analyze concentration profiles within the deposited phosphosilicate glass (PSG) for a range of POCl<sub>3</sub> conditions and develop a model to account for the experimentally observed time dependence of PSG thickness and dose(More)
Natural phosphatidylcholines, phosphatidylethanolamines and sphingomyelins have been investigated by field desorption and fast atom bombardment mass spectrometry. It is demonstrated that using these soft mass spectrometric ionization techniques, accurate, fast, and sensitive fatty acid profiling of phospholipids can be performed. With respect to the(More)
Levels of free and total cholesterol were quantified in control sera and human urine using [2H7]cholesterol or [13C2]cholesterol as internal standard and field desorption mass spectrometry for the quantification. These analyses are performed using a crude chloroform extract without chromatographic separation of the constituents. Due to the extremely soft(More)
The absorption and fluorescence spectra of 3-aminobenzo-1,2,4-triazine di-N-oxide (tirapazamine) have been recorded and exhibit a dependence on solvent that correlates with the Dimroth ET30 parameter. Time-dependent density functional theory calculations reveal that the transition of tirapazamine in the visible region is pi-->pi* in nature. The fluorescence(More)
Fluorescence quenching of a pyrylium salt (PDP2+) by toluene in acetonitrile gives rise to a nonexponential decay. This behavior is ascribed to the so-called transient effect occurring at high quencher concentrations for diffusion-controlled reactions. First, the Kalman filter was used to deconvolute the original signal from the experimental decay curve and(More)
  • 1