The drift field model applied to the lithium-containing silicon solar cell

The drift field model used by Wolf to calculate the short-circuit current was extended to permit calculations of the open-circuit voltage and the maximum power under conditions of illumination of either tungsten (2800 C) source or AMO sunlight. Voltages were calculated using an expression for the drift field diode saturation current derived here. The model, applied to the oxygen rich (C-13 group) lithium solar cells, was used to calculate the pre-and post-electron bombardment trends for lithium gradients in the range of 10 to the 18th power to 10 to the 19th power Li/cm to the 4th power. Published experimental data characterizing these cells were used to tailor the model. The calculated trends are in reasonable agreement with the empirical data of Faith. Diffusion length degradation and carrier removal effects were sufficient to predict the cell performance up to 3 x 10 to the 14th power e/sq cm. Beyond this fluence it was necessary to include drift field removal effects

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

Effects of high doping levels silicon solar cell performance

The significance of the heavy doping effects (HDE) on the open-circuit voltage of silicon solar cells is assessed. Voltage calculations based on diffusion theory are modified to include the first order features of the HDE. Comparisions of the open-circuit voltage measured for cells of various base resistivities are made with those calculated using the diffusion model with and without the HDE. Results indicate that the observed variation of voltage with base resistivity is predicted by these effects. A maximum efficiency of 19% (AM0) and a voltage of 0.7 volts are calculated for 0.1 omega-cm cells assuming an optimum diffused layer impurity profile

Radiation damage in lithium-counterdoped n/p silicon solar cells

Lithium counterdoped n+/p silicon solar cells were irradiated with 1 MV electrons and their post irradiation performance and low temperature annealing properties were compared to that of the 0.35 ohm cm control cells. Cells fabricated from float zone and Czochralski grown silicon were investigated. It was found that the float zone cells exhibited superior radiation resistance compared to the control cells, while no improvement was noted for the Czochralski grown cells. Room temperature and 60 C annealing studies were conducted. The annealing was found to be a combination of first and second order kinetics for short times. It was suggested that the principal annealing mechanism was migration of lithium to a radiation induced defect with subsequent neutralization of the defect by combination with lithium. The effects of base lithium gradient were investigated. It was found that cells with negative base lithium gradients exhibited poor radiation resistance and performance compared to those with positive or no lithium gradients; the latter being preferred for overall performance and radiation resistance

Experimental investigation of the excess charge and time constant of minority carriers in the thin diffused layer of 0.1 ohm-cm silicon solar cells

An experimental method is presented that can be used to interpret the relative roles of bandgap narrowing and recombination processes in the diffused layer. This method involves measuring the device time constant by open-circuit voltage decay and the base region diffusion length by X-ray excitation. A unique illuminated diode method is used to obtain the diode saturation current. These data are interpreted using a simple model to determine individually the minority carrier lifetime and the excess charge. These parameters are then used to infer the relative importance of bandgap narrowing and recombination processes in the diffused layer

Selbsthilfeorganisationen für seltene Erkrankungen und Gesundheitsversorgung: Gesundheitspolitische Erwartungen und Selbsthilferealität

Health policy expects self-help associations to make contributions to the improvement of the healthcare sector. The pilot study has explored the degree of reality of these expectations in a sample of five self-help organizations in the field of rare diseases. The study reveals that the expectations are fulfilled only in part. Self-help organizations enrich the healthcare sector with two specific qualities: their members operate with the special competencies of affected people and they have established a long-lasting cooperation with voluntary professionals. They are often a great help to the people contacting them directly, but, for a number of reasons, their supporting measures are reaching only a part of all affected people. The activities in the field of social participation have to cope with a lack of proper activists. They are able to pursue single projects successfully, but they are facing great problems in mastering the whole agenda of social participation

The Tet-on system for controllable gene expression in the rock-inhabiting black fungus Knufia petricola

Knufia petricola is a black fungus that colonizes sun-exposed surfaces as extreme and oligotrophic environments. As ecologically important heterotrophs and biofilm-formers on human-made surfaces, black fungi form one of the most resistant groups of biodeteriorating organisms. Due to its moderate growth rate in axenic culture and available protocols for its transformation and CRISPR/Cas9-mediated genome editing, K. petricola is used for studying the morpho-physiological adaptations shared by extremophilic and extremotolerant black fungi. In this study, the bacteria-derived tetracycline (TET)-dependent promoter (Tet-on) system was implemented to enable controllable gene expression in K. petricola. The functionality i.e., the dose-dependent inducibility of TET-regulated constructs was investigated by using GFP fluorescence, pigment synthesis (melanin and carotenoids) and restored uracil prototrophy as reporters. The newly generated cloning vectors containing the Tet-on construct, and the validated sites in the K. petricola genome for color-selectable or neutral insertion of expression constructs complete the reverse genetics toolbox. One or multiple genes can be expressed on demand from different genomic loci or from a single construct by using 2A self-cleaving peptides, e.g., for localizing proteins and protein complexes in the K. petricola cell or for using K. petricola as host for the expression of heterologous genes

The Case for Perspicuous Programming

This essay examines the nature of programs, classifies the traditional or enigmatic styles of programming, distinguishing template, prose and literate styles; notes the contrast between batch programs and interactive programs; and highlights the advantages of giving priority in developing interactive programs to the online documentation, and proposes that this documentation should be the principal target of development, with the executable program code being regarded of secondary and consequent

A narrative synthesis of women's out-of-body experiences during childbirth

Introduction Some women have a dissociated, out-of-body experience (OBE) during childbirth, which may be described as seeing the body from above or floating above the body. This review examines this phenomenon using narratives from women who have experienced intrapartum OBEs. Methods A narrative synthesis of qualitative research was employed to systematically synthesize OBE narratives from existing studies. Strict inclusion and exclusion criteria were applied. The included papers were critiqued by 2 of the authors to determine the appropriateness of the narrative synthesis method, procedural transparency, and soundness of the interpretive approach. Results Women experiencing OBEs during labor and birth report a disembodied state in the presence of stress or trauma. Three forms of OBEs are described: floating above the scene, remaining close to the scene, or full separation of a body part from the main body. Women had clear recall of OBEs, describing the experience and point of occurrence. Women who reported OBEs had experienced current or previous traumatic childbirth, or trauma in a non-birth situation. OBEs as prosaic experiences were not identified. Discussion OBEs are part of the lived experience of some women giving birth. The OBEs in this review were trauma related with some women disclosing previous posttraumatic stress disorder (PTSD). It is not evident whether there is a connection between PTSD and OBEs at present, and OBEs may serve as a potential coping mechanism in presence of trauma. Clinicians should legitimize women’s disclosure of OBEs and explore and ascertain their impact, either as a normal coping mechanism or a precursor to perinatal mental illness. Research into the function of OBEs and any relationship to PTSD may assist in early interventions for childbearing women