Gallium arsenide solar cell efficiency: Problems and potential

Under ideal conditions the GaAs solar cell should be able to operate at an AMO efficiency exceeding 27 percent, whereas to date the best measured efficiencies barely exceed 19 percent. Of more concern is the fact that there has been no improvement in the past half decade, despite the expenditure of considerable effort. State-of-the-art GaAs efficiency is analyzed in an attempt to determine the feasibility of improving on the status quo. The possible gains to be had in the planar cell. An attempt is also made to predict the efficiency levels that could be achieved with a grating geometry. Both the N-base and the P-base BaAs cells in their planar configurations have the potential to operate at AMO efficiencies between 23 and 24 percent. For the former the enabling technology is essentially in hand, while for the latter the problem of passivating the emitter surface remains to be solved. In the dot grating configuration, P-base efficiencies approaching 26 percent are possible with minor improvements in existing technology. N-base grating cell efficiencies comparable to those predicted for the P-base cell are achievable if the N surface can be sufficiently passivated

The effect of minority carrier mobility variations on solar cell spectral response

Analysis of multistep diffused, high voltage 0.1 ohm-cm solar cells suggests that the increased voltage capability of these cells is correlated with localized variations in the base minority carrier mobility. An attempt to calculate the behavior of those cells revealed unexpected results. It is shown, contrary to what was expected, that spatial variations in the mobility effects severe changes in the short-circuit current and the spectral response. Variations in cell output as a result of imposing abrupt, linear, and exponential mobility variations are presented

Low-high junction theory applied to solar cells

Recent use of alloying techniques for rear contact formation has yielded a new kind of silicon solar cell, the back surface field (BSF) cell, with abnormally high open circuit voltage and improved radiation resistance. Several analytical models for open circuit voltage based on the reverse saturation current are formulated to explain these observations. The zero SRV case of the conventional cell model, the drift field model, and the low-high junction (LHJ) model can predict the experimental trends. The LHJ model applies the theory of the low-high junction and is considered to reflect a more realistic view of cell fabrication. This model can predict the experimental trends observed for BSF cells. Detailed descriptions and derivations for the models are included. The correspondences between them are discussed. This modeling suggests that the meaning of minority carrier diffusion length measured in BSF cells be reexamined

9P Wielkopolanie o nowotworach

Od roku 1993 Pracownia a następnie Zakład Prewerencji i Epidemiologii Nowotworów gromadzi opinie mieszkańców Poznania i woj. poznańskiego na temat chorób nowotworowych. Celem prowadzonych badań jest aktualizowanie przekonań respondentów m. in. na temat czynników ryzyka chorób nowotworowych, źródeł wiedzy o nowotworach, czy akceptacji dla prowadzenia badań genetycznych.Opinie respondentów uzyskiwane są przy pomocy ankiety pocztowej, która przy zachowaniu podstawowej konstrukcji jest ulepszana kolejną edycją badań.Z analizy wynika, że*przekonania na temat wyleczalności nowotworów złośliwych utrzymują się na niezmienionym poziomie (większość oszacowań 11–30%),*za najbardziej skuteczną metodę leczenia nowotworów uważany jest zabieg chirurgiczny (42–53%),*wiedza respondentów o nowotworach pochodzi z artykułów prasowych, audycji TV, od rodziny i znajomych,*rośnie odsetek kobiet deklarujących znajomość samokontroli piersi (z 75% do 88%) oraz stosujących metodę systematycznie (wzrost 21% w ciągu trzech lat). Obserwowane tendencje stanowią element świadomości społecznej Wielkopolan, a dalsze badania powinny ujawnić ich trwałość oraz wpływ na kształtowanie stylu życia

Delivery and Acceptance Protocol of the Central Office Polish YMCA Branch Attached to A.P.W

1944. Delivery and Acceptance Protocol of the Central Office Polish YMCA Branch attached to A.P.W. (Polish Army in the East) in Junak Camps. Signed: Zofia Krzyżanowska (Zofia Drzewieniecki) and M. Godlewski. Dated: Tel-Aviv, March 3, 1944. (Document transferring all the funds, movables, accounting ledgers, documents, and the administrative office from the outgoing director Zofia Krzyżanowska to M. Godlewski.)https://digitalcommons.buffalostate.edu/ymcadocs/1061/thumbnail.jp

Voltage controlling mechanisms in low resistivity silicon solar cells: A unified approach

An experimental technique capable of resolving the dark saturation current into its base and emitter components is used as the basis of an analysis in which the voltage limiting mechanisms were determined for a variety of high voltage, low resistivity silicon solar cells. The cells studied include the University of Florida hi-low emitter cell, the NASA and the COMSAT multi-step diffused cells, the Spire Corporation ion-implanted emitter cell, and the University of New South Wales MINMIS and MINP cells. The results proved to be, in general, at variance with prior expectations. Most surprising was the finding that the MINP and the MINMIS voltage improvements are due, to a considerable extent, to a previously unrecognized optimization of the base component of the saturation current. This result is substantiated by an independent analysis of the material used to fabricate these devices