scholarly journals Scattering Theory of Graphene Grain Boundaries

2018 ◽  
Author(s):  
Francesco Romeo ◽  
Antonio Di Bartolomeo
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Scattering Theory ◽  
Chemical Vapor ◽  
Transmission Probability ◽  
Industrial Applications ◽  
Large Area ◽  
Current Conservation ◽  
Long Wavelength ◽  
Boundary Properties

The implementation of graphene-based electronics requires fabrication processes able to cover large device areas since exfoliation method is not compatible with industrial applications. Chemical vapor deposition of large-area graphene represents a suitable solution having the important drawback of producing polycrystalline graphene with formation of grain boundaries, which are responsible for limitation of the device performance. With these motivations, we formulate a theoretical model of graphene grain boundary by generalizing the graphene Dirac Hamiltonian model. The model only includes the long-wavelength regime of the particle transport, which provides the main contribution to the device conductance. Using symmetry-based arguments deduced from the current conservation law, we derive unconventional boundary conditions characterizing the grain boundary physics and analyze their implications on the transport properties of the system. Angle resolved quantities, such as the transmission probability, are studied within the scattering matrix approach. The conditions for the existence of preferential transmission directions are studied in relation with the grain boundary properties. The proposed theory provides a phenomenological model to study grain boundary physics within the scattering approach and represents per se an important enrichment of the scattering theory of graphene. Moreover, the outcomes of the theory can contribute in understanding and limiting detrimental effects of graphene grain boundaries also providing a benchmark for more elaborated techniques.

scholarly journals Scattering Theory of Graphene Grain Boundaries

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1660 ◽  
Author(s):  
Francesco Romeo ◽  
Antonio Di Bartolomeo
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Scattering Theory ◽  
Carrier Transport ◽  
Single Layer ◽  
Chemical Vapor ◽  
Industrial Applications ◽  
Single Layer Graphene ◽  
Large Area ◽  
Current Conservation

The implementation of graphene-based electronics requires fabrication processes that are able to cover large device areas, since the exfoliation method is not compatible with industrial applications. The chemical vapor deposition of large-area graphene represents a suitable solution; however, it has an important drawback of producing polycrystalline graphene with the formation of grain boundaries, which are responsible for the limitation of the device’s performance. With these motivations, we formulate a theoretical model of a single-layer graphene grain boundary by generalizing the graphene Dirac Hamiltonian model. The model only includes the long-wavelength regime of the charge carrier transport, which provides the main contribution to the device conductance. Using symmetry-based arguments deduced from the current conservation law, we derive unconventional boundary conditions characterizing the grain boundary physics and analyze their implications on the transport properties of the system. Angle resolved quantities, such as the transmission probability, are studied within the scattering matrix approach. The conditions for the existence of preferential transmission directions are studied in relation with the grain boundary properties. The proposed theory provides a phenomenological model to study grain boundary physics within the scattering approach, and represents per se an important enrichment of the scattering theory of polycrystalline graphene. Moreover, the outcomes of the theory can contribute to understanding and limiting the detrimental effects of graphene grain boundaries, while also providing a benchmark for more elaborate techniques.

Metal Microstructures in Advanced CMOS Devices

1996 ◽  
Vol 54 ◽  
pp. 358-359
Author(s):  
L. M. Gignac ◽  
K. P. Rodbell
Keyword(s):  
Grain Boundaries ◽  
Semiconductor Device ◽  
Chemical Vapor ◽  
Microstructural Characterization ◽  
Metal Films ◽  
Thin Metal ◽  
Electrical Performance ◽  
Thin Metal Films ◽  
Chemical Vapor Deposited ◽  
Boundary Properties

As advanced semiconductor device features shrink, grain boundaries and interfaces become increasingly more important to the properties of thin metal films. With film thicknesses decreasing to the range of 10 nm and the corresponding features also decreasing to sub-micrometer sizes, interface and grain boundary properties become dominant. In this regime the details of the surfaces and grain boundaries dictate the interactions between film layers and the subsequent electrical properties. Therefore it is necessary to accurately characterize these materials on the proper length scale in order to first understand and then to improve the device effectiveness. In this talk we will examine the importance of microstructural characterization of thin metal films used in semiconductor devices and show how microstructure can influence the electrical performance. Specifically, we will review Co and Ti silicides for silicon contact and gate conductor applications, Ti/TiN liner films used for adhesion and diffusion barriers in chemical vapor deposited (CVD) tungsten vertical wiring (vias) and Ti/AlCu/Ti-TiN films used as planar interconnect metal lines.

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.

Beam-Recrystallized Device-Worthy Films of Si on SiO2 via Control of the Grain Boundary Location

1983 ◽  
Vol 23 ◽  
Author(s):  
J.P. Colinge ◽  
D. Bensahel ◽  
M. Alamome ◽  
M. Haond ◽  
C. Leguet
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Laser Annealing ◽  
Ring Oscillators ◽  
Large Area ◽  
Leakage Currents ◽  
Back Gate ◽  
Boundary Location

ABSTRACTDevice-worthy films of silicon on SiO2 have been produced using laser annealing and antireflection stripes. If no seeding is used, grain boundaries will be localized beneath the stripes; with seeding, large-area single crystals can be grown, of uniform <100> orientation. N-channel transistors show a mobility of 620 cm2/V.s and present leakage currents which can be reduced, however, down to a few pA/um when the substrate (back gate) is negatively biased to − 5 V. Ring oscillators have also been made, which oscillate with a delay per stage of 1 nsec.

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.

The role of microscopy in the alloy design of Ni- and Fe-based aluminides

1992 ◽  
Vol 50 (1) ◽  
pp. 168-169
Author(s):  
J.A. Horton
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Oxidation Resistance ◽  
Industrial Applications ◽  
Al Alloys ◽  
Ordered Alloys ◽  
Successful Control ◽  
Oxidation Resistant

During the last 10 years, there has been a resurgence of interest in ordered alloys for structural uses due to the discovery of the dramatic ductilizing effect of boron on grain boundaries in Ni3Al. With this discovery, it was hoped that the property of an increase in strength as the temperature is increased could be utilized as well as the excellent oxidation resistance. Now, alloys based on Ni3Al are in use in specialized industrial applications, such as high temperature forging dies and being tested for use as turbocharger rotors. Due to the successful control of the grain boundary strength in Ni3Al, other systems were reexamined. For example, Fe3Al was also thought to have inherently brittle grain boundaries, however it was found that with purer alloys the material failed by cleavage. Subsequently, development of practical, inexpensive, oxidation resistant alloys has proceeded. Fe3Al alloys are currently being tested for automobile exhaust applications.

Grain Boundary and Misorientation Angle Dependent Thermal Transport in Single-layer MoS2

Nanoscale ◽  
2022 ◽  
Author(s):  
Ke Xu ◽  
Ting Liang ◽  
Zhisen Zhang ◽  
Xuezheng Cao ◽  
Meng Han ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Misorientation Angle ◽  
Thermal Transport ◽  
Single Layer ◽  
Large Area ◽  
Grain Misorientation

Grain boundaries (GBs) are inevitable defects in large-area MoS2 samples but play a key role in their properties, however, the influence of grain misorientation on thermal transport remains largely unknown...

Chemical Vapor Deposition Growth of Graphene Domains Across the Cu Grain Boundaries

NANO ◽  
2018 ◽  
Vol 13 (08) ◽  
pp. 1850088 ◽  
Author(s):  
Yang Wang ◽  
Yu Cheng ◽  
Yunlu Wang ◽  
Shuai Zhang ◽  
Chen Xu ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Growth Mechanism ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Growth ◽  
Domain Boundaries ◽  
Cvd Growth ◽  
Graphene Domain

Many aspects in the chemical vapor deposition (CVD) growth of graphene remain unclear such as its behavior near the catalyst grain boundaries. Here we investigate the CVD growth mechanism of graphene across the Cu grain boundaries using unidirectional aligned graphene domains, which simplifies the analysis of both graphene and Cu to a large extent. We found that for a graphene domain grown across the Cu grain boundary, the domain orientation is determined by the Cu grain where the domain nucleation center is located, and the Cu grain boundary will not change the growth behavior for this graphene domain. This growth mechanism is consistent with the Cu-step-attached nucleation and edge-attachment-limited growth mechanism for H-terminated graphene domains and will provide more guidance for the synthesis of high-quality graphene with less domain boundaries.

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