Modeling Boron Diffusion in Polycrystalline HfO2 Films

2002 ◽  
Vol 716 ◽  
Author(s):  
Chun-Li Liu
Keyword(s):  
Grain Boundary ◽  
Ab Initio ◽  
Grain Boundaries ◽  
Boundary Diffusion ◽  
Bulk Diffusion ◽  
Concentration Profiles ◽  
Boron Diffusion ◽  
Gate Stacks ◽  
Modeling Prediction ◽  
Sims Analysis

AbstractWe present ab-initio modeling results including formation, migration, and activation energies for B diffusion through bulk and grain boundaries in polycrystalline HfO2 films. Modeling results clearly indicate that B can penetrate through a 40 Å HfO2 film via grain boundary diffusion, but not by bulk diffusion. SIMS analysis of B concentration profiles for polysilicon/HfO2/Si gate stacks after different anneals showed double B peaks at the interfaces and thus confirmed the modeling prediction.

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.

scholarly journals Grain boundary diffusion and its relation to segregation of multiple elements in yttrium aluminum garnet

2020 ◽  
Vol 32 (6) ◽  
pp. 675-696
Author(s):  
Joana Polednia ◽  
Ralf Dohmen ◽  
Katharina Marquardt
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Yttrium Aluminum Garnet ◽  
Bulk Diffusion ◽  
Element Distribution ◽  
Grain Boundary Diffusion ◽  
Yttrium Aluminum ◽  
Detectable Concentration ◽  
Thin Film Diffusion ◽  
Strong Segregation

Abstract. We studied grain boundary diffusion and segregation of La, Fe, Mg, and Ti in a crystallographically defined grain boundary in yttrium aluminum garnet (YAG). Bi-crystals were synthesized by wafer bonding. Perpendicular to the grain boundary, a thin-film diffusion source of a La3.60Al4.40O12 was deposited by pulsed laser deposition. Diffusion anneals were performed at 1000 and 1450 ∘C. Via a gas phase small amounts of elements were added during the experiment. The element concentration distributions in our bi-crystals were mapped using analytical transmission electron microscopy (ATEM). Our results show strong segregation of La and Ti at the grain boundary. However, in the presence of Ti, the La concentrations dropped below the detection limit. Quantitative element distribution profiles along and across the grain boundary were fitted by a numerical diffusion model for our bi-crystal geometry that considers the segregation of elements into the grain boundary. The shape of the diffusion profiles of Fe requires the presence of two diffusion modes, e.g., the co-diffusion of Fe2+ as well as Fe3+. The absence of a detectable concentration gradient along the grain boundary in many experiments allows a minimum value to be determined for the product of sDgb. The resulting sDgb are a minimum of 7 orders of magnitude larger than their respective volume diffusion coefficient, specifically for La = 10−14 m2 s−1, Fe = 10−11 m2 s−1, Mg = Si = 10−12 m2 s−1, and Ti = 10−14 m2 s−1 at 1450 ∘C. Additionally, we model the effect of convolution arising from the given spatial resolution of our analysis with the resolution of our modeled system. Such convolution effects result in a non-unique solution for the segregation coefficient, e.g., for example for Mg between 2–3. Based on our data we predict that bulk diffusion of impurities in a mono-phase polycrystalline aggregate of YAG is effectively always dominated by grain boundary diffusion.

Stress Generation during Grain Boundary Interdiffusion

2011 ◽  
Vol 309-310 ◽  
pp. 19-28 ◽  
Author(s):  
Leonid Klinger ◽  
Eugen Rabkin
Keyword(s):  
Stress Field ◽  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Concentration Distribution ◽  
Boundary Diffusion ◽  
Elastic Stress ◽  
Bulk Diffusion ◽  
Stress Generation ◽  
Additional Material ◽  
Coupled Diffusion

A grain boundary interdiffusion in a semi-infinite bicrystal under the conditions of negligible bulk diffusion is considered. We show that the inequality of intrinsic grain boundary diffusion coefficients of the two components leads to plating out of additional material at the grain boundary in the form of extra material wedge, which generates an elastic stress field in the vicinity of the grain boundary. We solved a coupled diffusion/elasticity problem and determined the time-dependent stress field and concentration distribution in the vicinity of the grain boundary.

Grain Boundary Diffusion and Segregation in the Solid State Phase Transformations

1998 ◽  
Vol 527 ◽  
Author(s):  
E. Rabkin ◽  
W. Gust
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Solute Diffusion ◽  
Apparent Difference ◽  
Impurity Drag ◽  
The Difference ◽  
Boundary Width ◽  
Dynamic Segregation

ABSTRACTWe consider the problem of solute diffusion and segregation in the grain boundaries moving during a phase transformation in the framework of Cahn's impurity drag model. The concept of a dynamic segregation factor for the diffusion along moving grain boundaries is introduced. The difference between static and dynamic segregation factors may cause the apparent difference of the triple product of the segregation factor, grain boundary width and grain boundary diffusion coefficient for stationary and moving grain boundaries. The difference between static and dynamic segregation is experimentally verified for the Cu(In)-Bi system, for which the parameters of static segregation are well-known. It is shown that the complications associated with the dynamic segregation may be avoided during the study of the discontinuous ordering reaction. From the kinetics of this reaction, the activation energy of the grain boundary self-diffusion can be determined.

Diffusion Mechanisms in Nanocrystalline and Nanolaminated Au-Cu

2007 ◽  
Vol 266 ◽  
pp. 13-28 ◽  
Author(s):  
Alan F. Jankowski
Keyword(s):  
Low Temperature ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Diffusion ◽  
Bulk Diffusion ◽  
Grain Boundary Diffusion ◽  
Dominant Mechanism ◽  
Temperature Range ◽  
Diffusion Mechanisms ◽  
Kinetics Of

Thermal anneal treatments are used to identify the temperature range of the two dominant diffusion mechanisms – bulk and grain boundary. To assess the transition between mechanisms, the low temperature range for bulk diffusion is established utilizing the decay of static concentration waves in composition-modulated nanolaminates. These multilayered structures are synthesized using vapor deposition methods as thermal evaporation and magnetron sputtering. However, at low temperature the kinetics of grain-boundary diffusion are much faster than bulk diffusion. The synthesis of Au-Cu alloys (0-20 wt.% Cu) with grain sizes as small as 5 nm is accomplished using pulsed electro-deposition. Since the nanocrystalline grain structure is thermally unstable, these structures are ideal for measuring the kinetics of grain boundary diffusion as measured by coarsening of grain size with low temperature anneal treatments. A transition in the dominant mechanism for grain growth from grain boundary to bulk diffusion is found with an increase in temperature. The activation energy for bulk diffusion is found to be 1.8 eV·atom-1 whereas that for grain growth at low temperatures is only 0.2 eV·atom-1. The temperature for transitioning from the dominant mechanism of grain boundary to bulk diffusion is found to be 57% of the alloy melt temperature and is dependent on composition.

Grain boundary Diffusion of Ni through Pd2Si

1983 ◽  
Vol 25 ◽  
Author(s):  
E. C. Zingu ◽  
J. W. Mayer
Keyword(s):  
Thin Film ◽  
Activation Energy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Diffusion ◽  
Rutherford Backscattering Spectrometry ◽  
High Mobility ◽  
Grain Boundary Diffusion ◽  
Rutherford Backscattering

ABSTRACTInterdiffusion in the Si<100>/Pd2Si/Ni and Si<111>/Pd2Si/Ni thin film systems has been investigated using Rutherford backscattering spectrometry. Nickel is found to diffuse along the grain boundaries of polycrystalline Pd2Si upon which it accumulates at the Si<100>Pd2Si interface. The high mobility of Ni compared to that of si suggests that Pd diffuses faster than Si along the Pd2Si grain boundaries. An activation energy of 1.2 eV is determined for Ni grain boundary diffusion in Pd2Si.

Constrained Grain Boundary Diffusion In Thin Copper Films

2004 ◽  
Vol 821 ◽  
Author(s):  
Markus J. Buehler ◽  
Alexander Hartmaier ◽  
Huajian Gao
Keyword(s):  
Thin Films ◽  
Theoretical Analysis ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Atomic Scale ◽  
Diffusional Creep ◽  
Copper Films ◽  
And Diffusion

AbstractIn a recent study of diffusional creep in polycrystalline thin films deposited on substrates, we have discovered a new class of defects called the grain boundary diffusion wedges (Gao et al., Acta Mat. 47, pp. 2865-2878, 1999). These diffusion wedges are formed by stress driven mass transport between the free surface of the film and the grain boundaries during the process of substrate-constrained grain boundary diffusion. The mathematical modeling involves solution of integro-differential equations representing a strong coupling between elasticity and diffusion. The solution can be decomposed into diffusional eigenmodes reminiscent of crack-like opening displacement along the grain boundary which leads to a singular stress field at the root of the grain boundary. We find that the theoretical analysis successfully explains the difference between the mechanical behaviors of passivated and unpassivated copper films during thermal cycling on a silicon substrate. An important implication of our theoretical analysis is that dislocations with Burgers vector parallel to the interface can be nucleated at the root of the grain boundary. This is a new dislocation mechanism in thin films which contrasts to the well known Mathews-Freund-Nix mechanism of threading dislocation propagation. Recent TEM experiments at the Max Planck Institute for Metals Research have shown that, while threading dislocations dominate in passivated metal films, parallel glide dislocations begin to dominate in unpassivated copper films with thickness below 400 nm. This is consistent with our theoretical predictions. We have developed large scale molecular dynamics simulations of grain boundary diffusion wedges to clarify the nucleation mechanisms of parallel glide in thin films. Such atomic scale simulations of thin film diffusion not only show results which are consistent with both continuum theoretical and experimental studies, but also revealed the atomic processes of dislocation nucleation, climb, glide and storage in grain boundaries. The study should have far reaching implications for modeling deformation and diffusion in micro- and nanostructured materials.

Glancing angle x-ray study of the effect of oxygen on interface reactions in Al/Ni bilayers

1991 ◽  
Vol 6 (5) ◽  
pp. 935-942 ◽  
Author(s):  
S.M. Heald ◽  
E.V. Barrera
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Bulk Diffusion ◽  
Diffusion Path ◽  
Initial Reaction ◽  
X Ray ◽  
Interface Reactions ◽  
Glancing Angle ◽  
Effect Of Oxygen ◽  
Oxygen Impurities

Glancing angle x-ray reflectivity and EXAFS measurements have been made on a series of UHV prepared Al/Ni bilayers with varying amounts of oxygen impurities. These samples show an intrinsic reacted region prior to annealing, and for clean samples further reaction occurs at 250 °C. Oxygen is found to influence strongly the course of the reaction with an effect which depends on its location. A few percent O impurity within the Al film strongly suppresses the grain boundary diffusion path, which allows the growth of a smooth NiAl3 layer. Interfacial O exposures of 60 and 600 Langmuir both inhibit the initial reaction and raise the temperature at which further reaction occurs to as much as 300 °C with an effect which depends on exposure. The thickness of the intrinsic reaction zone is about 60 Å for clean samples, and is nearly eliminated for contaminated interfaces. The results indicate that surface/interface, grain boundary, and bulk diffusion all play important roles in the formation of these interfaces, and that each of these is influenced by O impurities.

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