scholarly journals The Relevance of Point Defects in Studying Silica-Based Materials from Bulk to Nanosystems

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1378 ◽  
Author(s):  
Antonino Alessi ◽  
Jochen Kuhnhenn ◽  
Gianpiero Buscarino ◽  
Diego Di Francesca ◽  
Simonpietro Agnello
Keyword(s):  
Point Defects ◽  
Physical Phenomenon ◽  
Device Performance ◽  
Impact Device ◽  
Macroscopic Properties ◽  
Defect Species

The macroscopic properties of silica can be modified by the presence of local microscopic modifications at the scale of the basic molecular units (point defects). Such defects can be generated during the production of glass, devices, or by the environments where the latter have to operate, impacting on the devices’ performance. For these reasons, the identification of defects, their generation processes, and the knowledge of their electrical and optical features are relevant for microelectronics and optoelectronics. The aim of this manuscript is to report some examples of how defects can be generated, how they can impact device performance, and how a defect species or a physical phenomenon that is a disadvantage in some fields can be used as an advantage in others.

Atomic transport via point defects in crystals III. Migration in a stress field

1985 ◽  
Vol 398 (1814) ◽  
pp. 203-208 ◽  
Keyword(s):  
Stress Field ◽  
Point Defects ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Molecular Volume ◽  
Uniform Stress ◽  
Atomic Transport ◽  
Elastic Dipole ◽  
Uniform Stress Field ◽  
Defect Species

The kinetic theory of isothermal atomic transport via point defects that was presented in two previous papers (Franklin, A. D. & Lidiard, A. B. Proc. R. Soc. Lond . A 389, 405–431 (1983) and Franklin, A. D. & Lidiard, A. B. Proc. R. Soc. Lond . A 392, 457–473 (1984)) has been expanded into a three-dimensional formulation to analyse transport in an applied non-uniform stress field. The fluxes of the various defect species take the general form familiar from non-equilibrium thermodynamics, while the contribution to the force on defect species Y arising from the stress σ αβ is confirmed to be v ∇(λ (Y) αβ σ αβ ), where v is the molecular volume of the solid and λ (Y) αβ is the elastic-dipole strain tensor of the defect species Y (summation over repeated Cartesian indices α, β is here assumed). Full details of these calculations are presented in Lidiard, A. B. A. E. R. E. Rep . no R. 11367 (1984).

Energetics and electronic structure of point defects associated with oxygen excess at a tilt boundary of ZnO

2000 ◽  
Vol 15 (10) ◽  
pp. 2167-2175 ◽  
Author(s):  
Fumiyasu Oba ◽  
Hirohiko Adachi ◽  
Isao Tanaka
Keyword(s):  
Electronic Structure ◽  
Point Defects ◽  
First Principles ◽  
Electronic States ◽  
Tilt Boundary ◽  
Oxygen Excess ◽  
Zno Varistors ◽  
Formation Energies ◽  
Defect Species ◽  
Static Lattice

The formation energies and electronic structure of zinc vacancies and oxygen interstitials at a tilt boundary of ZnO were investigated by a combination of static lattice and first-principles molecular orbital methods. For both of the defect species, the formation energies were lower than those of the bulk defects at certain sites in the grain boundary. The defects with low formation energies formed electronic states close to the top of the valence band. The interfacial electronic states observed experimentally in ZnO varistors cannot be explained solely by the point defects associated with the oxygen excess: the effects of impurities should be significant for the states.

Effect of doping Ti on the vacancy trapping mechanism for helium in ZrCo from first principles

2019 ◽  
Vol 21 (37) ◽  
pp. 20909-20918
Author(s):  
Qingqing Wang ◽  
Xianggang Kong ◽  
You Yu ◽  
Huilei Han ◽  
Ge Sang ◽  
...  
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Trapping Mechanism ◽  
Macroscopic Properties ◽  
Properties Of Materials ◽  
Vacancy Trapping ◽  
Effect Of Doping

The interactions of dopants with point defects such as that between vacancies and helium can affect helium evolution and ultimately the macroscopic properties of materials.

Theoretical Evaluation of Anisotropic Distortion Associated with Point Defects in Ordered Compounds

2015 ◽  
Vol 363 ◽  
pp. 101-105
Author(s):  
Maaouia Souissi ◽  
Ryusuke Nakamura ◽  
Hiroshi Numakura
Keyword(s):  
Ab Initio Calculations ◽  
Point Defects ◽  
Single Point ◽  
Structure Optimization ◽  
Relaxation Effect ◽  
Relaxation Strength ◽  
Theoretical Evaluation ◽  
Full Structure ◽  
The Difference ◽  
Defect Species

To verify the assumption that the anelastic relaxation effect observed in Ni3Al is due to stress-induced reorientation of antisite Al atoms [Numakura and Nishi, Mater. Sci. Eng. A 442 (2006) 59-62], the magnitudes of the anisotropic distortion produced by the intrinsic point defects have been evaluated by ab initio calculations. The anisotropy of the λ tensor (the strain per unit concentration of a particular defect) for the two candidate defect species, namely a Ni vacancy and an antisite Al atom, has been computed by full structure optimization of a supercell containing a single point defect: the difference in the principal values is +0.46 and −1.12, respectively. The relaxation strength estimated for antisite Al atoms agrees fairly well with experiment, while that for Ni vacancies is far too small because of their much lower concentration. The relaxation is, therefore, conclusively attributed to antisite Al atoms.

scholarly journals Processing Techniques with Heating Conditions for Multiferroic Systems of BiFeO3, BaTiO3, PbTiO3, CaTiO3 Thin Films

2021 ◽  
Author(s):  
Kuldeep Chand Verma ◽  
Manpreet Singh
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Physical Phenomenon ◽  
Synthesis Methods ◽  
Device Performance ◽  
Free Film ◽  
Thin Film Fabrication ◽  
Chip Size ◽  
Film Fabrication ◽  
Long Range Ordering

In this chapter, we have report a list of synthesis methods (including both synthesis steps & heating conditions) used for thin film fabrication of perovskite ABO3 (BiFeO3, BaTiO3, PbTiO3 and CaTiO3) based multiferroics (in both single-phase and composite materials). The processing of high quality multiferroic thin film have some features like epitaxial strain, physical phenomenon at atomic-level, interfacial coupling parameters to enhance device performance. Since these multiferroic thin films have ME properties such as electrical (dielectric, magnetoelectric coefficient & MC) and magnetic (ferromagnetic, magnetic susceptibility etc.) are heat sensitive, i.e. ME response at low as well as higher temperature might to enhance the device performance respect with long range ordering. The magnetoelectric coupling between ferromagnetism and ferroelectricity in multiferroic becomes suitable in the application of spintronics, memory and logic devices, and microelectronic memory or piezoelectric devices. In comparison with bulk multiferroic, the fabrication of multiferroic thin film with different structural geometries on substrate has reducible clamping effect. A brief procedure for multiferroic thin film fabrication in terms of their thermal conditions (temperature for film processing and annealing for crystallization) are described. Each synthesis methods have its own characteristic phenomenon in terms of film thickness, defects formation, crack free film, density, chip size, easier steps and availability etc. been described. A brief study towards phase structure and ME coupling for each multiferroic system of BiFeO3, BaTiO3, PbTiO3 and CaTiO3 is shown.

Device Dielectric Quality Analysis and Fault Isolation at the Contact Level by Scanning Microwave Impedance Microscopy

2016 ◽  
Author(s):  
Wei-Shan Hu ◽  
Jeng-Han Lee ◽  
Ming-Hong Kao ◽  
Hui-Wen Yang ◽  
Peter De Wolf ◽  
...  
Keyword(s):  
Dielectric Film ◽  
Gate Oxide ◽  
Fault Isolation ◽  
Quality Monitoring ◽  
Quality Analysis ◽  
Device Performance ◽  
Analysis Techniques ◽  
Impact Device ◽  
Electrical Analysis

Abstract Dielectric film quality is one of the most important factors that will greatly impact device performance and reliability. Device level electrical analysis techniques for dielectric quality monitoring are highly needed. In this paper we present results using a new electrical AFM mode, scanning Microwave Impedance Microscopy (sMIM), for characterization of device oxide quality and for fault isolation. Devices with poor oxide quality show sMIM nano C-V and dC/dV hysteresis behavior during forward and reverse bias sweep. The sMIM capacitance sensitivity is below 1 aF allowing one to capture C-V spectra from the MOS structure formed by the gate and gate oxide with excellent signal/noise ratio and observe subtle variations between different sites.

Fabrication and Properties of Single, Double, and Triple Gate Polycrystalline-Silicon Thin Film Transistors

1987 ◽  
Vol 106 ◽  
Author(s):  
R. E. Proano ◽  
R. J. Soave
Keyword(s):  
Thin Film ◽  
Point Defects ◽  
Thin Film Transistors ◽  
Single Crystal Silicon ◽  
Electrical Performance ◽  
Intrinsic Point Defect ◽  
Device Performance ◽  
Silicon Thin Film ◽  
Crystal Silicon ◽  
Effective Electron

ABSTRACTPolysilicon based Thin Film Transistors (poly-Si TFT's) with superior electrical performance can be achieved by maximizing the number of intrinsic point defect injected into the material during high temperature processing. These point defects will migrate to grain boundaries (GB's), enhance their mobility by facilitating climb, and allow the boundary to achieve a low energy configuration with a minimum of electrically active broken bonds. Proper processing of poly-Si TFT's therefore requires a redesign of the conventional processing cycle where, working with single crystal silicon, one minimizes the concentration of intrinsic point defects which otherwise precipitate out as Oxidation induced Stacking Faults (OSF's).TFT's were fabricated under nine different processing cycles to study the relationship between device performance and fabrication conditions. Device performance increased with higher gate oxidation temperature, elimination of HCI flow during gate oxidation, post hydrogenation, and multiple gates. Using conventional MOS processing steps only, n-type (p-type) devices were fabricated, which were capable of handling 40 volts VDS with a leakage current of 2×10−11 (6×10−12) A/μm and effective electron (hole) channel mobilities of 130 (50) cm2/Vs.

Microstructural Evolution in Reduced TiO2

1981 ◽  
Vol 39 ◽  
pp. 74-75
Author(s):  
W. T. Donlon ◽  
S. Shinozaki ◽  
E. M. Logothetis ◽  
W. Kaizer
Keyword(s):  
Microstructural Evolution ◽  
Point Defects ◽  
Extended Defects ◽  
Small Deviations ◽  
Controlled Atmospheres ◽  
Limited Solubility ◽  
Thin Foils ◽  
Heat Treated ◽  
Porous Polycrystalline ◽  
Crystallographic Shear

Since point defects have a limited solubility in the rutile (TiO2) lattice, small deviations from stoichiometry are known to produce crystallographic shear (CS) planes which accomodate local variations in composition. The material used in this study was porous polycrystalline TiO2 (60% dense), in the form of 3mm. diameter disks, 1mm thick. Samples were mechanically polished, ion-milled by conventional techniques, and initially examined with the use of a Siemens EM102. The electron transparent thin foils were then heat-treated under controlled atmospheres of CO/CO2 and H2 and reexamined in the same manner.The “as-received” material contained mostly TiO2 grains (∼5μm diameter) which had no extended defects. Several grains however, aid exhibit a structure similar to micro-twinned grains observed in reduced rutile. Lattice fringe images (Fig. 1) of these grains reveal that the adjoining layers are not simply twin related variants of a single TinO2n-1 compound. Rather these layers (100 - 250 Å wide) are alternately comprised of stoichiometric TiO2 (rutile) and reduced TiO2 in the form of Ti8O15, with the Ti8O15 layers on either side of the TiO2 being twin related.

Simulated Dark-Field Electron Micrographs of Point Defects and Organometallics

1975 ◽  
Vol 33 ◽  
pp. 200-201
Author(s):  
William Krakow
Keyword(s):  
Electron Micrographs ◽  
Point Defects ◽  
Structure Determination ◽  
Atomic Structure ◽  
Image Interpretation ◽  
Dark Field ◽  
Field Electron ◽  
Dark Field Microscopy ◽  
Dark Field Electron

Tilted beam dark-field microscopy has been applied to atomic structure determination in perfect crystals, several synthesized molecules with heavy atcm markers and in the study of displaced atoms in crystals. Interpretation of this information in terms of atom positions and atom correlations is not straightforward. Therefore, calculated dark-field images can be an invaluable aid in image interpretation.

Particle characterization of CVD tungsten metallization for 64 MBIT DRAM

1991 ◽  
Vol 49 ◽  
pp. 896-897
Author(s):  
Marylyn Bennett-Lilley ◽  
Thomas T.H. Fu ◽  
David D. Yin ◽  
R. Allen Bowling
Keyword(s):  
Chemical Vapor ◽  
Device Performance ◽  
Particle Characterization ◽  
Particle Generation ◽  
Tungsten Hexafluoride ◽  
Homogeneous Particle ◽  
Multiple Levels ◽  
Circuit Density ◽  
Sources Of Contamination

Chemical Vapor Deposition (CVD) tungsten metallization is used to increase VLSI device performance due to its low resistivity, and improved reliability over other metallization schemes. Because of its conformal nature as a blanket film, CVD-W has been adapted to multiple levels of metal which increases circuit density. It has been used to fabricate 16 MBIT DRAM technology in a manufacturing environment, and is the metallization for 64 MBIT DRAM technology currently under development. In this work, we investigate some sources of contamination. One possible source of contamination is impurities in the feed tungsten hexafluoride (WF6) gas. Another is particle generation from the various reactor components. Another generation source is homogeneous particle generation of particles from the WF6 gas itself. The purpose of this work is to investigate and analyze CVD-W process-generated particles, and establish a particle characterization methodology.

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