Effect of Grain Boundary Segregation on the Transbarrier Conductivity of Polycrystalline Silicon

1990 ◽  
Vol 182 ◽  
Author(s):  
S. Pizzini ◽  
M. Acciarri
Keyword(s):  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Carrier Transport ◽  
Boundary Segregation ◽  
Mean Free Path ◽  
Thermally Activated ◽  
Heat Treated ◽  
Initial Oxygen ◽  
Set Up ◽  
New Hypothesis

AbstractThe conductivity of single grain boundaries of electronic grade, Bridgman grown polycrystalline silicon samples was measured using the dc polarization technique with the aim of detecting any influence on the carrier transport regime resulting from the segregation of oxygen and carbon, which, by themselves, should behave as electrically inactive impurities. To this scope as grown samples and samples heat treated at 1123 and 1223 K, differing in their initial oxygen and carbon content, were used and the conductivity measured in the 298-100 K range.The results indicate that for both the carbon rich and for the oxygen rich samples the conductivity across the grain boundaries is of the thermally activated type and that it could be discussed in terms of carriers which are thermally emitted over the barrier and cross the barrier in the limit of the short mean free path.Samples which do not present a net excess of oxygen or carbon, apparently behave as single crystal specimens, instead.The deconvolution of the I-V curves is then used for obtaining the densitl of the interface states responsible of the set-up of the grain boundaries barrier, whose shape supports a completely new hypothesis about the configuration of the impurity cloud at the grain boundaries.

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

scholarly journals Carrier Transport across a Few Grain Boundaries in Highly Doped Polycrystalline Silicon

2001 ◽  
Vol 40 (Part 2, No. 6B) ◽  
pp. L615-L617 ◽  
Author(s):  
Yoshikazu Furuta ◽  
Hiroshi Mizuta ◽  
Kazuo Nakazato ◽  
Yong T. Tan ◽  
Toshio Kamiya ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Carrier Transport

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.

Effect of grain alignment on lateral carrier transport in aligned-crystalline silicon films on polycrystalline substrates

2007 ◽  
Vol 22 (4) ◽  
pp. 821-825 ◽  
Author(s):  
Woong Choi ◽  
Alp T. Findikoglu ◽  
Manuel J. Romero ◽  
Mowafak Al-Jassim
Keyword(s):  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Carrier Transport ◽  
Crystalline Silicon ◽  
Silicon Films ◽  
Dangling Bond ◽  
Grain Alignment ◽  
Bond Density ◽  
Polycrystalline Silicon Films ◽  
Trapping Sites

We report the studies on the effect of grain alignment on lateral carrier transport in nominally 〈001〉-oriented aligned-crystalline silicon (ACSi) films on polycrystalline substrates. With improving grain alignment, energy barrier height at the grain boundaries was reduced from 150 to less than 1 meV, and both conductivity and Hall mobility became less sensitive to hydrogen passivation. This suggests that the dangling bonds in ACSi films are a major source of trapping sites, and that they become less dominant with improving grain alignment. These results demonstrate that improving grain alignment enhances the lateral carrier transport in small-grained (≤1 μm) polycrystalline silicon films, by reducing dangling bond density at the grain boundaries.

Carrier transport across grain boundaries in polycrystalline silicon thin film transistors

2016 ◽  
Vol 31 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Yong Chen ◽  
Shuang Zhang ◽  
Zhang Li ◽  
Hanhua Huang ◽  
Wenfeng Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Grain Boundaries ◽  
Thin Film Transistors ◽  
Polycrystalline Silicon ◽  
Carrier Transport ◽  
Silicon Thin Film

Carbide precipitation and chromium depletion on coherent twin boundaries in deformed 304 stainless steels

1992 ◽  
Vol 50 (2) ◽  
pp. 1216-1217
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Stainless Steels ◽  
Interfacial Free Energy ◽  
Carbide Precipitation ◽  
Twin Boundaries ◽  
Invariant Structure ◽  
Heat Treated ◽  
Constant Structure ◽  
Cr Depletion

Coherent annealing-twin boundaries are constant structure and energy interfaces with an average interfacial free energy of ∼19mJ/m2 versus ∼210 and ∼835mJ/m2 for incoherent twins and “regular” grain boundaries respectively in 304 stainless steels (SS). Due to their low energy, coherent twins form carbides about a factor of 100 slower than grain boundaries, and limited work has also shown differences in Cr-depletion (sensitization) between twin versus grain boundaries. Plastic deformation, may, however, alter the kinetics and thermodynamics of twin-sensitization which is not well understood. The objective of this work was to understand the mechanisms of carbide precipitation and Cr-depletion on coherent twin boundaries in deformed SS. The research is directed toward using this invariant structure and energy interface to understand and model the role of interfacial characteristics on deformation-induced sensitization in SS. Carbides and Cr-depletion were examined on a 20%-strain, 0.051%C-304SS, heat treated to 625°C-4.5h, as described elsewhere.

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

Experiments on the flow of heat in liquid helium below 0.7 °K

1958 ◽  
Vol 246 (1246) ◽  
pp. 390-405 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Liquid Helium ◽  
Free Path ◽  
Empirical Relation ◽  
Mean Free Path ◽  
Series Of Experiments ◽  
The Mean ◽  
Set Up ◽  
Low Pressures ◽  
Measured Thermal Conductivity

A series of experiments has been performed to study the steady flow of heat in liquid helium in tubes of diameter 0.05 to 1.0 cm at temperatures between 0.25 and 0.7 °K. The results are interpreted in terms of the flow of a gas of phonons, in which the mean free path λ varies with temperature, and may be either greater or less than the diameter of the tube d . When λ ≫ d the flow is limited by the scattering of the phonons at the walls, and the effect of the surface has been studied, but when λ ≪ d viscous flow is set up in which the measured thermal conductivity is increased above that for wall scattering. This behaviour is very similar to that observed in the flow of gases at low pressures, and by applying kinetic theory to the problem it can be shown that the mean free path of the phonons characterizing viscosity can be expressed by the empirical relation λ = 3.8 x 10 -3 T -4.3 cm. This result is inconsistent with the temperature dependence of λ as T -9 predicted theoretically by Landau & Khalatnikov (1949).

Application of Tailored Heat Treated Blanks under Quasi Series Conditions

2007 ◽  
Vol 344 ◽  
pp. 383-390 ◽  
Author(s):  
Marion Merklein ◽  
Uwe Vogt
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Local Heat ◽  
Strength Distribution ◽  
Process Window ◽  
Short Term ◽  
Forming Process ◽  
Heat Treated ◽  
Set Up ◽  
The Impact

Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank’s local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today’s car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.

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