The Effect of Heat Treatment on Grain Boundary Properties in Cast Polycrystalline Silicon

1981 ◽  
Vol 5 ◽  
Author(s):  
P.E. Russell ◽  
C.R. Herrington ◽  
D.E. Burke ◽  
P.H. Holloway
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Surface Recombination ◽  
Device Fabrication ◽  
Solar Cell Device ◽  
Device Structure ◽  
Heat Treated ◽  
Boundary Properties

ABSTRACTThe effects of heat treatment at temperatures appropriate for solar cell device fabrication on grain boundaries in cast poicrystalline silicon have been studied. An MIS device structure using a 200° C heating was used for fabricating test devices on heat treated samples for EBIC studies. Grain boundary effective surface recombination velocities (Seffgb ) and effective mid-grain diffusion lengths were measured. Seffgb was found to increase after heat treatment. Segregation of oxygen to grain boundaries has been observed in heat treated samples.

Passive and Enhanced Grain Boundaries in Solar Cells by Gas Immersion Laser Diffusion

1981 ◽  
Vol 5 ◽  
Author(s):  
G. B. Turner ◽  
D. Tarrant ◽  
D. Aldrich ◽  
R. Pressley ◽  
R. Press
Keyword(s):  
Heat Treatment ◽  
Solar Cells ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Pulsed Laser ◽  
New Method ◽  
Current Collection ◽  
Liquid Diffusion ◽  
Epitaxial Regrowth

ABSTRACTA new method for making p-n junctions based on immersion in a transparent dopant gas followed by irradiation with a pulsed laser is presented. The surface of the wafer melts, dopant from the gas dissolves in it, and is distributed by liquid diffusion before epitaxial regrowth. This technique, termed GILD for Gas Immersion Laser Diffusion, was used to make solar cells in both monocrystalline and polycrystalline silicon.Laser photocurrent scanning shows that grain boundary recombination is reduced or eliminated in cells made by the GILD technique and current collection is enhanced at some grain boundaries. Heat treatment at 850 ° C prior to GILD causes the same grain boundaries to be recombination active as they are in ordinary diffused cells.

Survey of Grain Boundary Energies in Four Elemental Metals

2012 ◽  
Vol 715-716 ◽  
pp. 179-179
Author(s):  
David L. Olmsted ◽  
Elizabeth A. Holm ◽  
Stephen M. Foiles
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Energy Minimization ◽  
Boundary Energy ◽  
Atomic Scale ◽  
Energy Structure ◽  
Grain Boundary Energy ◽  
Fcc Metals ◽  
Composition And Structure ◽  
Boundary Properties

Grain boundary properties depend on both composition and structure. To test the relative contributions of composition and structure to the grain boundary energy, we calculated the energy of 388 grain boundaries in four elemental, fcc metals: Ni, Al, Au and Cu. We constructed atomic-scale bicrystals of each boundary and subjected them to a rigorous energy minimization process to determine the lowest energy structure. Typically, several thousand boundary configurations were examined for each boundary in each element.

Atomic Scale Characterisation of Electrodeposited Nanocrystalline Ni-P Alloys

1999 ◽  
Vol 581 ◽  
Author(s):  
Matthias Abraham ◽  
Mattias Thuvandert ◽  
Helen M. Lane ◽  
Alfred Cerezo ◽  
George D.W. Smith
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Boundary Segregation ◽  
Atom Probe ◽  
Atomic Scale ◽  
Grain Boundary Segregation ◽  
P Concentration

ABSTRACTNanocrystalline Ni-P alloys produced by electrodeposition have been characterised by three-dimensional atom probe (3DAP) analysis. In the as-deposited materials, there are indications of some variation in P concentration between grains and segregation to grain boundaries. After heat treatment however, strong grain boundary segregation and the formation of Ni3P precipitates have been observed.

Advantages of MIS Processing on Passivated Polycrystalline Silicon

1981 ◽  
Vol 5 ◽  
Author(s):  
G. Rajeswaran ◽  
M. Thayer ◽  
V. J. Rao ◽  
W. A. Anderson
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Hydrogen Plasma ◽  
Mis Structures

ABSTRACTWacker polycrystalline silicon shows enhanced grain boundary activity after a high temperature (950° C) anneal. It is possible to passivate this effect in a hydrogen plasma. The low temperature (600° C) processing of MIS technology does not activate grain boundaries or deteriorate a passivated specimen. Activated grain boundaries with MIS structures can be used to assess the character of recombination currents. It is concluded that MIS processing is advantageous for passivated polycrystalline silicon.

Precipitation of Copper and Cobalt at Grain Boundaries in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
U. Jendrich ◽  
H. J. Möller
Keyword(s):  
Particle Size ◽  
Mössbauer Spectroscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Cooling Rate ◽  
Polycrystalline Silicon ◽  
Mossbauer Spectroscopy ◽  
Low Energy ◽  
Surface Source ◽  
Mößbauer Spectroscopy

AbstractThe precipitation of copper and (radioactive) cobalt at low energy grain boundaries in polycrystalline silicon and bicrystals is investigated. The metals are diffused in from a surface source between 800 - 1000 °C and the precipitation after cooling down is studied by TEM (for Cu) and Mößbauer spectroscopy (for Co). The precipitates are metal suicides. For copper it is shown that they appear in form of colonies containing hundreds of precipitates with a particle size between 5-60 nm. In the grain boundary they nucleate preferentially at dislocations and steps. The distribution and size of the precipitates depend on the cooling rate after the diffusion. In the vicinity of the grain boundary the volume is depleted from the impurities.

Anisotropic Behaviour of Grain Boundaries

2005 ◽  
Vol 482 ◽  
pp. 63-70 ◽  
Author(s):  
Václav Paidar ◽  
Pavel Lejček
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Materials ◽  
Grain Boundary Engineering ◽  
Interfacial Dislocation ◽  
Special Character ◽  
Boundary Properties ◽  
Properties Of Materials ◽  
Boundary Classification ◽  
Boundary Chemistry

Grain boundaries are decisive for many properties of materials. Due to short-range stress field their influence is primarily based on their atomic structure. Special character of grain boundary properties related to their structure, follows from the nature of atomic arrangements in the boundary cores, from the interfacial dislocation content and from the boundary mobility. All those aspects of boundary behaviour are strongly influenced by the boundary chemistry including various segregation phenomena. Approaches to the boundary classification and the interpretation of recent experimental results are discussed in the context of the complex relationship between microstructure and material properties. Such findings are essential for Grain Boundary Engineering proposed to improve the performance of polycrystalline materials.

Monte Carlo Simulation of Solute-Atom Segregation at Grain Boundaries In Single-Phase Binary Face-Centered Cubic Alloys

1998 ◽  
Vol 4 (S2) ◽  
pp. 764-765
Author(s):  
David N. Seidman ◽  
John D. Rittner ◽  
Dmitry Udler
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Solute Atom ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Diffusional Creep ◽  
Boundary Structure ◽  
Temper Brittleness ◽  
Face Centered Cubic ◽  
Boundary Properties

Solute-atom segregation to grain boundaries has been of interest since the 1930's when it was realized that some steels were susceptible to failure by intergranular fracture when certain impurities were present. Segregation of impurities or intentionally added alloying elements at grain boundaries can greatly affect various grain boundary properties, which in turn affect numerous macroscopic properties. Materials phenomena that have been linked to grain boundary segregation include temper brittleness, fatigue strength, adhesion, precipitation, diffusional creep, intergranular corrosion, and grain boundary diffusivity. Although grain boundary segregation has been extensively studied for many years, the effects of different grain boundary structures on segregation was generally not considered. It has been established both experimentally and theoretically that the level of segregation varies from grain boundary to grain boundary in the same alloy, but there is little direct information on how grain boundary structure influences segregation.

High-resolution TEM of grain boundaries in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 428-429
Author(s):  
H. FÖll ◽  
D.G. Ast
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Large Scale ◽  
Boundary Structure ◽  
Scale Production ◽  
Silicon Crystals ◽  
Grain Boundary Structure ◽  
Large Scale Production ◽  
High Resolution Tem ◽  
Boundary Properties

In contrast to grain boundaries in metals, little is known about the structure and the properties of grain boundaries in covalent crystals, especially in semiconductors. The reason for this lack of knowledge is that grain-boundary-free crystals of, e.g., silicon, are easy to grow; commercially used silicon crystals are free of dislocations and thus nearly perfect. It was not until after the use of polycrystalline silicon had been proposed for the large scale production of cheap solar cells that grain-boundary properties in silicon gained considerable interest. In particular their electronic properties and their influence on device performance is important in this case. Moreover, “grain boundary devices”, i.e., devices with a grain boundary as the active element and with rather interesting properties, are conceivable - provided the relationship between the grain boundary structure and their electronic behaviour can be understood (cf. /l/). In addition, the study of grain boundaries in silicon, with an electronic structure and a binding configuration very different from metals, may provide a valuable tool to test competing grain boundary models (see, e.g., /2,3/) and may lead to a deeper insight into the crystal parameters governing the grain boundary properties.

Grain Boundary Engineering of Metals by Thermo-Mechanical Treatment

2010 ◽  
Vol 659 ◽  
pp. 349-354
Author(s):  
Péter János Szabó
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Stainless Steels ◽  
Mechanical Treatment ◽  
Austenitic Stainless Steels ◽  
Grain Boundary Engineering ◽  
Aisi 304 ◽  
Relative Fraction ◽  
Heat Treated ◽  
Thermo Mechanical Treatment

The relative fraction of the special grain boundaries can be increased by thermo-mechanical treatments. During this work, AISI 304-type austenitic stainless steels were plastically deformed and heat treated under different conditions, and then the grain boundary network, which developed during the treatments was investigated. Results showed that cyclic application of large cold rolling (30% reduction of thickness) and quick heat treatment at high temperature (800 °C, 2 minutes) gave the best grain boundary network. A possible reason of this behaviour is that grains which did not recrystallize after the first cycle, stored a high elastic energy, which helped the grain boundary motions in the next cycles. To characterize the developed grain boundary network, different parameters are also suggested in this paper.

Boron Diffusion in Polycrystalline Silicon

1986 ◽  
Vol 76 ◽  
Author(s):  
Moustafa Y. Ghannam ◽  
Robert W. Dutton ◽  
Steven W. Novak
Keyword(s):  
Grain Size ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Boundary Diffusion ◽  
Crystalline Silicon ◽  
Unit Area ◽  
Grain Boundary Diffusion ◽  
Boron Diffusion

ABSTRACTThe diffusion of boron in ion implanted LPCVD polycrystalline silicon is shown to be dominated by grain boundary diffusion at low and moderate concentrations. The diffusion coefficient is 2 to 3 orders of magnitude larger than its value in crystalline silicon. In preannealed polysilicon, the boron diffusion coefficient is found to be 30% smaller than in polysilicon annealed after implantation. This reflects the effect of the grain size in the diffusion coefficient since preannealed polysilicon has larger grains and smaller density of grain boundaries per unit area.

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