Heat exchanger-ingot casting/slicing process: Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project
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Schmid, F.↗
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Heat exchanger method-, ingot casting fixed abrasive method: Multiwire slicing. Phase 2: Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project
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Schmid, F.↗
Heat exchanger method, ingot casting; fixed abrasive method, multi-wire slicing, phase 2. Silicon sheet growth development for the large area sheet task of the low cost silicon solar array project
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Schmid, F.↗
Silicon sheet growth development for the large area silicon sheet task of the low cost solar array project. Quantitative analysis of defects in silicon
The various steps involved in obtaining quantitative information of structural defects in crystalline silicon samples are described. Procedures discussed include: (1) chemical polishing; (2) chemical etching; and (3) automated image analysis of samples on the QTM 720 System.
Natesh, R.↗
Low cost solar array project: Composition measurements by analytical photon catalysis
The applicability of the photon catalysis technique for effecting composition analysis of silicon samples is assessed. In particular, the technique is to be evaluated as a detector for the impurities Al, Cr, Fe, Mn, Ti, V, Mo and Zr. During the first reporting period Al, Cr, Fe and Mn were detected with the photon catalysis method. The best fluorescence lines to monitor and determined initial sensitivities to each of these elements by atomic absorption calibration were established. In the course of these tests, vapor pressure curves for these four pure substances were mapped.
Sutton, D. G.↗
Low cost silicon solar array project: Feasibility of low-cost, high-volume production of silane and pyrolysis of silane to semiconductor-grade silicon
Silicon epitaxy analysis of silane produced in the Process Development Unit operating in a completely integrated mode consuming only hydrogen and metallurgical silicon resulted in film resistivities of up to 120 ohms cm N type. Preliminary kinetic studies of dichlorosilane disproportionation in the liquid phase have shown that 11.59% SiH4 is formed at equilibrium after 12 minutes contact time at 56 C. The fluid-bed reactor was operated continuously for 48 hours with a mixture of one percent silane in helium as the fluidizing gas. A high silane pyrolysis efficiency was obtained without the generation of excessive fines. Gas flow conditions near the base of the reactor were unfavorable for maintaining a bubbling bed with good heat transfer characteristics. Consequently, a porous agglomerate formed in the lower portion of the reactor. Dense coherent plating was obtained on the silicon seed particles which had remained fluidizied throughout the experiment.
Breneman, W. C.↗
Development of an Accelerated Test Design for Predicting the Service Life of the Solar Array at Mead, Nebraska
Potential long-term degradation modes for the two types of modules in the Mead array were determined and judgments were made as to those environmental stresses and combinations of stresses which accelerate the degradation of the power output. Hierarchical trees representing the severity of effects of stresses (test conditions) on eleven individual degradation modes were constructed and were pruned of tests judged to be nonessential. Composites of those trees were developed so that there is now one pruned tree covering eight degradation modes, another covering two degradation modes, and a third covering one degradation mode. These three composite trees form the basis for selection of test conditions in the final test plan which is now being prepared.
Gaines, G. B.↗
Low Cost Silicon Solar Array Project. Feasibility of Low-cost, High-volume Production of Silane and Pyrolysis of Silane to Semiconductor-grade Silicon
The presence of copper promotes a more rapid approach to the steady stete operating condition and results in a more consistent reactor effluent composition. The average kinetic and equilibrium yield are unchanged. Incoloy has been identified as the preferred choice of material of construction for the hydrogenation reactor although certain metallurgical changes were noted in samples exposed to the H2/HCl atmosphere at 500 C which indicate the need for more testing.
Breneman, W. C.↗
Continuous Czochralski Growth. Silicon Sheet Growth Development of the Large Area Silicon Sheet Task of the Low Cost Silicon Solar Array Project
The JPL Continuous Czochralski Growth Facility is now essentially complete and is functional. In this reporting period, a silicon lump recharging device was designed, and a prototype was built which performed well in simulated recharge tests. The large chamber (designed to accommodate a 14-inch hot zone) was put into operation initially with the standard hot zone in order to compare performance with previous experience. Some modifications were made to the hot zones in the larger chamber due to considerably larger radiative heat losses. Several short (one-ingot) runs were performed and four continuous runs were attempted. The largest continuous run lasted 64 hours and produced 57 kilograms of ingot.
Merz, F.↗
Low Cost Solar Array Project: Composition Measurements by Analytical Photo Catalysis
The applicability of the photon catalysis technique for effecting composition analysis of silicon samples is discussed. A detector for the impurities Al, Cr, Fe, Mn, Ti, V, Mo and Zr is evaluated. During the first reporting period Al, Cr, Fe, and Mn were detected with the photon catalysis method. The best fluorescence lines to monitor and determine initial sensitivities to each of these elements by atomic absorption calibration were established. In the course of these tests vapor pressure curves for these four pure substances were also mapped. Ti and Si were detected. The best lines to monitor were catalogued and vapor pressure curves were determined. Attempts to detect vanadium were unsuccessful due to the refractory nature of this element and the limited temperature range of the evaporator.
Sutton, D. G.↗
Plasma sheath effects and voltage distributions of large high-power satellite solar arrays
Knowledge of the floating voltage configuration of a large array in orbit is needed in order to estimate various plasma-interaction effects. The equilibrium configuration of array voltages relative to space depends on the sheath structure. The latter dependence for an exposed array is examined in the light of two finite-sheath effects. One effect is that electron currents may be seriously underestimated. The other is that a potential barrier for electrons can occur, restricting electron currents. A conducting surface is assumed on the basis of a conductivity argument. Finite-sheath effects are investigated. The results of assuming thin-sheath and thick-sheath limits on the floating configuration of a linearly connected array are studied. Sheath thickness and parasitic power leakage are estimated. Numerically computed fields using a 3-D code are displayed in the thick-sheath limit.
Parker, L. W.↗
LSA: Low-cost Solar Array project
Topics discussed include silicon material processing; large-area silicon sheet development; encapsulation materials testing and development; project engineering and operations activities, and manufacturing techniques. The steps taken to integrate these efforts, are described.
Source record↗
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.
Baghdadi, A.↗
Quantitative analysis of defects in silicon: Silicon sheet growth development for the large area silicon sheet task of the low cost solar array project
The various steps involved in the chemical polishing and etching of silicon samples are described and the data on twins, grain boundaries and dislocation pits from fifty-three (53) samples are discussed.
Natesh, R.↗
Low-cost solar array project
Technology development and technical feasibility are reviewed. Process and materials candidates to meet project goals were investigated. Integration of technical development with cost estimates is discussed.
Callaghan, W. T.↗
Analysis and Evaluation of Processes and Equipment in Tasks 2 and 4 of the Low-cost Solar Array Project
The significant economic data for the current production multiblade wafering and inner diameter slicing processes were tabulated and compared to data on the experimental and projected multiblade slurry, STC ID diamond coated blade, multiwire slurry and crystal systems fixed abrasive multiwire slicing methods. Cost calculations were performed for current production processes and for 1982 and 1986 projected wafering techniques.
Goldman, H.↗
Quantitative Analysis of Defects in Silicon. Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low-cost Solar Array Project
The various steps involved in the chemical polishing and etching of silicon samples are described. Data on twins, dislocation pits, and grain boundaries from thirty-one (31) silicon sample are also discussed. A brief review of the changes made to upgrade the image analysis system is included.
Natesh, R.↗
Development of a Process for a High Capacity Arc Heater Production of Silicon for Solar Arrays
A program was established to develop a high temperature silicon production process using existing electric arc heater technology. Silicon tetrachloride and a reductant (sodium) are injected into an arc heated mixture of hydrogen and argon. Under these high temperature conditions, a very rapid reaction is expected to occur and proceed essentially to completion, yielding silicon and gaseous sodium chloride. Techniques for high temperature separation and collection were developed. Included in this report are: test system preparation; testing; injection techniques; kinetics; reaction demonstration; conclusions; and the project status.
Reed, W. H.↗