Structure and Electronic Properties of Diamond-Like Amorphous Carbon

1994 ◽  
Vol 349 ◽  
Author(s):  
C. Z. Wang ◽  
K. M. Ho
Keyword(s):  
Electronic Properties ◽  
Amorphous Carbon ◽  
Ion Beam ◽  
Tight Binding ◽  
Carbon Films ◽  
Structural And Electronic Properties ◽  
Carbon Networks ◽  
Tetrahedral Bonding ◽  
Dynamics Method ◽  
Beam Deposition

ABSTRACTAmorphous carbon networks generated by quenching high-density liquid from hightemperature using a tight-binding molecular dynamics method are found to be dominated by tetrahedral bonding sites. The overall structural and electronic properties of these networks resemble those observed in experimental diamond-like amorphous carbon films produced by the mass-selected ion beam deposition technique. Our study shows that bonding and antibonding of π states associated with pairs and quartets of threefold “defected-atoms” embedded in the fourfold matrix yield a band gap of about 2 eV.

Ion Beam Deposition of Amorphous Carbon Films With Diamond Like Properties

1981 ◽  
Vol 7 ◽  
Author(s):  
John C. Angus ◽  
Michael J. Mirtich ◽  
Edwin G. Wintucky
Keyword(s):  
Amorphous Carbon ◽  
Growth Rates ◽  
Random Network ◽  
Ion Beam ◽  
Potassium Bromide ◽  
Carbon Films ◽  
Amorphous Carbon Films ◽  
Ion Beam Deposition ◽  
Beam Deposition

ABSTRACTCarbon films were deposited on silicon, quartz, and potassium bromide substrates from an ion beam. Growth rates were approximately 0.3 μm/hour. The films were featureless and amorphous and contained only carbon and hydrogen in significant amounts. The density and carbon/hydrogen ratio indicate the film is a hydrogen deficient polymer. One possible structure, consistent with the data, is a random network of methylene linkages and tetrahedrally coordinated carbon atoms.

Elastic Properties of Diamond-Like Amorphous Carbon Films Grown by Computer Simulation of Ion-Beam Deposition Process

2000 ◽  
Vol 648 ◽  
Author(s):  
A.Yu. Belov ◽  
H.U. Jäger
Keyword(s):  
Amorphous Carbon ◽  
Elastic Constants ◽  
Ion Beam ◽  
Carbon Films ◽  
Atomic Scale ◽  
Ion Energy ◽  
Amorphous Carbon Films ◽  
Ion Beam Deposition ◽  
Bulk Stress ◽  
Beam Deposition

AbstractAtomic-scale calculations were performed for the first time to investigate mechanical properties of amorphous carbon films grown by a realistic simulation of ion-beam deposition. The simulated films have a thickness of a few nanometers and reproduce the main structural features of real films, with the bulk content of sp3 bonded atoms varying from 35 to 95%, depending on the ion energy (E = 20-80 eV). Employing empirical interatomic potentials for carbon, the average bulk stresses as well as the atomic-level stress distributions were calculated and analysed. The bulk stresses were found to depend not only on the ion energy, but also on the film quality, in particular, on such structural inhomogeneities as local fluctuations of the sp3 fraction with the depth. The local variation of the bulk stress from the average value considerably increases as the local content of sp2 bonded atoms increases. Elastic constants of amorphous carbon films were also computed using the method of inner elastic constants, which allows for the stress dependence of elastic constants to be analysed. The variation of Young's modulus as a function of the lateral bulk stress in an amorphous film is demonstrated.

Carbon Film Deposition On Silicon Using Low Energy Ion Beams

1991 ◽  
Vol 223 ◽  
Author(s):  
Qin Fuguang ◽  
Yao Zhenyu ◽  
Ren Zhizhang ◽  
S.-T. Lee ◽  
I. Bello ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ion Beam ◽  
Carbon Film ◽  
Carbon Films ◽  
Film Deposition ◽  
Ion Energy ◽  
Transmission Electron ◽  
Higher Temperature ◽  
Post Implantation ◽  
Beam Deposition

ABSTRACTDirect ion beam deposition of carbon films on silicon in the ion energy range of 15–500eV and temperature range of 25–800°C has been studied using mass selected C+ ions under ultrahigh vacuum. The films were characterized with X-ray photoelectron spectroscopy, Raman spectroscopy, and transmission electron microscopy and diffraction analysis. Films deposited at room temperature consist mainly of amorphous carbon. Deposition at a higher temperature, or post-implantation annealing leads to formation of microcrystalline graphite. A deposition temperature above 800°C favors the formation of microcrystalline graphite with a preferred orientation in the (0001) direction. No evidence of diamond formation was observed in these films.

scholarly journals STRUCTURAL AND ELECTRONIC PROPERTIES OF TRANSITION METAL DI-CHALCOGENIDES (MX2) M=(Mo, W) AND X=(S, Se) IN BULK STATE: A FIRST-PRINCIPLES STUDY

2017 ◽  
Vol 22 (1) ◽  
pp. 41-50
Author(s):  
Ram Prasad Sedhain ◽  
Gopi Chandra Kaphle
Keyword(s):  
Transition Metal ◽  
Electronic Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Calculated Data ◽  
Modern Technology ◽  
Fundamental Aspect ◽  
Bulk State ◽  
Error Bar ◽  
Structural And Electronic Properties

Transition metal di-chalcogenides (MX2) M=(Mo, W) and X=(S, Se) in bulk state are of great interest due to their diverse applications in the field of modern technology as well as to understand the fundamental aspect of Physics. We performed structural and electronic properties of selected systems using density functional theory implemented in Tight Binding Linear Muffin- tin Orbital (TBLMTO) approach with subsequent refinement. The structural optimization is performed through energy minimization process and lattice parameters of optimized structures for MoS2, MoSe2, WS2 and WSe2 are found to be 3.20Å, 3.34Å, 3.27Å and 3.34Å respectively, which are within the error bar less than 5% with experimental values. The band gaps for all TMDCs are found to be of indirect types with semiconducting behaviours. The values of band gap of MoS2, MoSe2, WS2 and WSe2 in bulk state are found to be 1.16eV, 108eV, 1.50eV and 1.29eV respectively which are comparable with experimental and previously calculated data. Due to the symmetric nature of up spin and down spin channels of Density of States (DOS) all the systems selected are found to be non magnetic. However it fully supports the results obtained from band structure calculations. The potential and charge distributions plots support the results. The charge density plots reveals the covalent nature of bond in (100) plane. However (110) plane shows mixed types of bonding.Journal of Institute of Science and TechnologyVolume 22, Issue 1, July 2017, page: 41-50

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