Laser-zone Growth in a Ribbon-to-ribbon (RTR) Process Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Solar Array Project

A technique for growing limited-length ribbons continually was demonstrated. This Rigid Edge technique can be used to recrystallize about 95% of the polyribbon feedstock. A major advantage of this method is that only a single, constant length silicon ribbon is handled throughout the entire process sequence; this may be accomplished using cassettes similar to those presently in use for processing Czochralski waters. Thus a transition from Cz to ribbon technology can be smoothly affected. The maximum size being considered, 3 inches x 24 inches, is half a square foot, and will generate 6 watts for 12% efficiency at 1 sun. Silicon dioxide has been demonstrated as an effective, practical diffusion barrier for use during the polyribbon formation

The automated array assembly task of the low-cost silicon solar array project, phase 2

Several specific processing steps as part of a total process sequence for manufacturing silicon solar cells were studied. Ion implantation was identified as the preferred process step for impurity doping. Unanalyzed beam ion implantation was shown to have major cost advantages over analyzed beam implantation. Further, high quality cells were fabricated using a high current unanalyzed beam. Mechanically masked plasma patterning of silicon nitride was shown to be capable of forming fine lines on silicon surfaces with spacings between mask and substrate as great as 250 micrometers. Extensive work was performed on advances in plated metallization. The need for the thick electroless palladium layer was eliminated. Further, copper was successfully utilized as a conductor layer utilizing nickel as a barrier to copper diffusion into the silicon. Plasma etching of silicon for texturing and saw damage removal was shown technically feasible but not cost effective compared to wet chemical etching techniques

Processing experiments on non-Czochralski silicon sheet

A program is described which supports and promotes the development of processing techniques which may be successfully and cost-effectively applied to low-cost sheets for solar cell fabrication. Results are reported in the areas of process technology, cell design, cell metallization, and production cost simulation

Parry and Parry’s Disease

THE MANIn 1778 the Charter of Incorporation was granted by George Ill to the presidents and associates of the Medical Society of Edinburgh, confirming Robert Freer, James Melliar, Andrew Wardrop and Caleb Parry in their office as Presidents. Caleb Parry, whose name appears here, became a highly esteemed practitioner at Bath and like Heberden acquired a lifelong habit of taking notes. He described the first recorded case of facial hemiatrophy in 1814, of congenital idiopathic dilatation of the colon in 1825, and in 1786 he left an account of exophthalmic goitre so complete and original that it more justly entitles him to the honour of its discovery than either Flajani in 1800, Graves in 1835, or von Basedow in 1840.Caleb Hillier Parry was born on October 21st 1755, at Cirencester, near Gloucester, where his father Joshua was a non-conformist minister. His early education was at the grammar school in Cirencester, where he met Edward Jenner: and the latter dedicated his epochal Inquiry in the Causes and Effects of the Variolae Vaccinae" to "C. H. Parry, M.D., at Bath, My Dear Friend." At the age of 18, Parry became a student of medicine at Edinburgh, in the days when William Cullen dominated the scene. Parry spent two of his undergraduate years in London, but when he returned in 1777, he was elected a president of the Medical Society of Edinburgh. And it was during his term of office that the Royal Charter was achieved, an honour which remains unique for an undergraduate society

Laser-zone growth in a Ribbon-To-Ribbon (RTR) process. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

The Ribbon-to-Ribbon (RTR) approach to silicon ribbon growth is investigated. An existing RTR apparatus is to be upgraded to its full capabilities and operated routinely to investigate and optimize the effects of various growth parameters on growth results. A new RTR apparatus was constructed to incorporate increased capabilities and improvements over the first apparatus and to be capable of continuous growth. New high power lasers were implemented and this led to major improvements in growth velocity -- 4 inch/min. growth has been demonstrated. A major step in demonstration of the full feasibility of the RTR process is reported in the demonstration of RTR growth from CVD polyribbon rather than sliced polyribbon ingots. Average solar cell efficiencies of greater than 9% and a best cell efficiency of 11.7% are reported. Processing was shown to provide a substantial improvement in material minority carrier diffusion length. An economic analysis is reported which treats both the polyribbon fabrication and RTR processes

Laser-zone growth in a Ribbon-To-Ribbon (RTR) process. Silicon sheet growth development for the large area sheet task of the low-cost solar array project

A new calculation of the effects of thermal stresses during growth on silicon ribbon quality is reported. Thermal stress distributions are computed for ribbon growth under a variety of temperature profiles. A growth rate of 55 cu cm/min with a single ribbon was achieved. The growth of RTR ribbon with a fairly uniform parallel dendritic structure was demonstrated. Results with two approaches were obtained for reducing the Mo impurity level in polycrystalline feedstock. Coating the Mo substrate with Si3N4 does not effect thermal shear separation of the polyribbon; this process shows promise of improving cell efficiency and also increasing the useful life of the molybdenum substrate. A number of solar cells were fabricated on RTR silicon grown from CVD feedstock

Issues for designing and evaluating a 'heroin trial': three discussion papers

Report on a workshop on trial evaluation / G. Bammer and D.N. McDonald -- An evaluation of possible designs for a heroin trial / R.G. Jarrett and P.J. Solomon -- Service provision considerations for the evaluation of a heroin trial. A discussion paper / D.N. McDonald, G. Bammer, D.G. Legge and B.M. Sibthorpe

Optimized delivery of siRNA into 3D tumor spheroid cultures in situ

3D tissue culture provides a physiologically relevant and genetically tractable system for studying normal and malignant human tissues. Despite this, gene-silencing studies using siRNA has proved difficult. In this study, we have identified a cause for why traditional siRNA transfection techniques are ineffective in eliciting gene silencing in situ within 3D cultures and proposed a simple method for significantly enhancing siRNA entry into spheroids/organoids. In 2D cell culture, the efficiency of gene silencing is significantly reduced when siRNA complexes are prepared in the presence of serum. Surprisingly, in both 3D tumour spheroids and primary murine organoids, the presence of serum during siRNA preparation rapidly promotes entry and internalization of Cy3-labelled siRNA in under 2 hours. Conversely, siRNA prepared in traditional low-serum transfection media fails to gain matrigel or spheroid/organoid entry. Direct measurement of CTNNB1 mRNA (encoding β-catenin) from transfected tumour spheroids confirmed a transient but significant knockdown of β-catenin when siRNA:liposome complexes were formed with serum, but not when prepared in the presence of reduced-serum media (Opti-MEM). Our studies suggest a simple modification to standard lipid-based transfection protocols facilitates rapid siRNA entry and transient gene repression, providing a platform for researchers to improve siRNA efficiency in established 3D cultures

Laser-zone growth in a ribbon-to-ribbon (RTR) process silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project. Technical quarterly report no. 8, April 1--June 30, 1978

Further progress in growth rate has been made, reaching an area throughput rate of 38 cm/sup 2//min. This growth rate was achieved, using CVD feedstock, both with a 7.6 cm wide ribbon grown at 5 cm/min and a 5 cm wide ribbon grown at 7.6 cm/min. The 5 cm wide ribbon exhibited a dendritic structure; although the ribbon showed a tendency to buckle in the non-dendritic region, it was perfectly flat once the dendrites were firmly established. The 7.6 cm wide ribbon was non-dendritic, and had severe buckling. A new design for an improved furnace for RTR growth has been completed. The semi-continuous polysilicon CVD ribbon reactor has been designed and is being assembled and tested. A study of the microstructure of dendrites growing in RTR ribbon has shown that they contain a small, usually even, number of parallel twins. Electrical activity of defects in RTR ribbon has been studied by fabricating an array of photodiodes on the ribbon, and using an SEM in the electron beam induced current (EBIC) mode. The first solar cell on RTR ribbon grown from CVD feedstock was fabricated. The overall efficiency was 6.7%, with I/sub SC/ = 24 mA/cm/sup 2/, V/sub OC/ = 0.53 volts, fill factor = 0.53. Total cell area was 2.5 cm/sup 2/. The Mo impurity level was measured in a few CVD samples by Neutron Activation analysis. This analysis indicated a Mo level of 5 to 10 ppM in the bulk of the silicon ribbon