skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Density determination of nano-layers depending to the thickness by non-destructive method

Abstract

Non-destructive tests used to characterize and observe the state of the solids near the surface or at depth, without damaging them or damaging them. Density is frequently used to follow the variations of the physical structure of the samples, as well as in the calculation of quantity of material required to fill a given volume, and it is also used to determine the homogeneity of a sample. However, the measurement of the acoustic properties (density, elastic constants,…) of a thin film whose thickness is smaller than several atomic layers is not easy to perform. For that reason, we expose in this work the effects of the thicknesses of thin films on the evolution of the density, where several samples are analyzed. The samples selected structures are thin films deposited on substrates, these coatings have thicknesses varying from a few atomic layers to ten or so micrometers and can change the properties of the substrate on which they are deposited. To do so, we considered a great number of layers (Cr, Al, SiO{sub 2}, ZnO, Cu, AlN, Si{sub 3}N{sub 4}, SiC) deposited on different substrates (Al{sub 2}O{sub 3}, Cu and Quartz). It is first shown that the density exhibits a dispersivemore » behaviour. Such a behaviour is characterized by an initial increase (or decrease) followed by a saturated region. Further investigations of these dependences led to the determination of a semi-empirical universal relations, ρ=f(h/λ{sub T}), for all the investigated layer/substrate combination. Such expression could be of great importance in the density prediction of even layers thicknesses.« less

Authors:
 [1]; ;  [2]
  1. Département des Sciences Fondamentales, Faculté des Sciences et Sciences de l'Ingénieur, Université 20 Aout.1955, Skikda, BP 26, DZ-21000 Algérie and Laboratoire des Semi-Conducteurs, Département de Physique (Algeria)
  2. Laboratoire des Semi-Conducteurs, Département de Physique, Faculté des Sciences, Université Badji-Mokhtar, BP 12, Annaba, DZ-23000 (Algeria)
Publication Date:
OSTI Identifier:
22261690
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1569; Journal Issue: 1; Conference: 3. international advances in applied physics and materials science congress, Antalya (Turkey), 24-28 Apr 2013; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM NITRIDES; ALUMINIUM OXIDES; DENSITY; DEPOSITS; LAYERS; SILICON CARBIDES; SILICON NITRIDES; SILICON OXIDES; SOLIDS; SUBSTRATES; THICKNESS; THIN FILMS; ZINC OXIDES

Citation Formats

Gacem, A., Doghmane, A., and Hadjoub, Z.. Density determination of nano-layers depending to the thickness by non-destructive method. United States: N. p., 2013. Web. doi:10.1063/1.4849256.
Gacem, A., Doghmane, A., & Hadjoub, Z.. Density determination of nano-layers depending to the thickness by non-destructive method. United States. doi:10.1063/1.4849256.
Gacem, A., Doghmane, A., and Hadjoub, Z.. 2013. "Density determination of nano-layers depending to the thickness by non-destructive method". United States. doi:10.1063/1.4849256.
@article{osti_22261690,
title = {Density determination of nano-layers depending to the thickness by non-destructive method},
author = {Gacem, A. and Doghmane, A. and Hadjoub, Z.},
abstractNote = {Non-destructive tests used to characterize and observe the state of the solids near the surface or at depth, without damaging them or damaging them. Density is frequently used to follow the variations of the physical structure of the samples, as well as in the calculation of quantity of material required to fill a given volume, and it is also used to determine the homogeneity of a sample. However, the measurement of the acoustic properties (density, elastic constants,…) of a thin film whose thickness is smaller than several atomic layers is not easy to perform. For that reason, we expose in this work the effects of the thicknesses of thin films on the evolution of the density, where several samples are analyzed. The samples selected structures are thin films deposited on substrates, these coatings have thicknesses varying from a few atomic layers to ten or so micrometers and can change the properties of the substrate on which they are deposited. To do so, we considered a great number of layers (Cr, Al, SiO{sub 2}, ZnO, Cu, AlN, Si{sub 3}N{sub 4}, SiC) deposited on different substrates (Al{sub 2}O{sub 3}, Cu and Quartz). It is first shown that the density exhibits a dispersive behaviour. Such a behaviour is characterized by an initial increase (or decrease) followed by a saturated region. Further investigations of these dependences led to the determination of a semi-empirical universal relations, ρ=f(h/λ{sub T}), for all the investigated layer/substrate combination. Such expression could be of great importance in the density prediction of even layers thicknesses.},
doi = {10.1063/1.4849256},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1569,
place = {United States},
year = 2013,
month =
}
  • In the work, we study the mechanisms of structural phase state formation in NiTi surface layers after low-energy pulsed electron beam irradiation depending on the electron beam energy density. It is revealed that after electron beam treatment of the NiTi specimens at energy densities E{sub 1} = 15 J/cm{sup 2}, E{sub 2} = 20 J/cm{sup 2}, and E{sub 3} = 30 J/cm{sup 2}, a series of effects is observed: the absence of the Ti2Ni phase and the presence of new peaks correspond to the B19′ martensite phase with monoclinic structure. Estimation of the relative volume content of the B2 andmore » B19′ phases from the total intensity of their peaks shows that the percentage of the martensite phase increases from ∼5 vol.% in the NiTi specimen irradiated at E{sub 1} = 15 J/cm{sup 2} to ∼80 vol.% in the NiTi specimen irradiated at E{sub 3} = 30 J/cm{sup 2}. It is found that in the NiTi specimens irradiated at E ≤ 20 J/cm{sup 2}, the layer that contains a martensite phase resides not on the surface but at some depth from it.« less
  • Due to their tunable properties, silicon nano-crystals (NC) are currently being investigated. Quantum confinement can generally be employed for size-dependent band-gap tuning at dimensions smaller than the Bohr radius (∼5 nm for silicon). At the nano-meter scale, however, increased surface-to-volume ratio makes the surface effects dominant. Specifically, in Si-SiO{sub 2} core-shell semiconductor NCs the interfacial transition layer causes peculiar electronic and optical properties, because of the co-existence of intermediate oxidation states of silicon (Si{sup n+}, n = 0–4). Due to the presence of the many factors involved, a comprehensive understanding of the optical properties of these NCs has not yet been achieved. Inmore » this work, Si-SiO{sub 2} NCs with a diameter of 1.1 nm and covered by amorphous oxide shells with thicknesses between 2.5 and 4.75 Å are comprehensively studied, employing density functional theory calculations. It is shown that with increased oxide shell thickness, the low-energy part of the optical transition spectrum of the NC is red shifted and attenuated. Moreover, the absorption coefficient is increased in the high-energy part of the spectrum which corresponds to SiO{sub 2} transitions. Structural examinations indicate a larger compressive stress on the central silicon cluster with a thicker oxide shell. Examination of the local density of states reveals the migration of frontier molecular orbitals from the oxide shell into the silicon core with the increase of silica shell thickness. The optical and electrical properties are explained through the analysis of the density of states and the spatial distribution of silicon sub-oxide species.« less
  • The accuracy of a destructive, experimental method for the evaluation of through-thickness residual stress distributions is investigated. The application of the method is to a welded pipe that has been subjected to a residual stress improvement process. The residual stress improvement process introduces gradients in the stress distributions. The question of interest is how well the back-computation method used to interpret the experimental data represents the residual stress distribution for this type of stress profile. To address this question, a finite element model was used to provide a reference stress solution for comparison with the back-computation results of the experimentalmore » method. Three-dimensional finite element stress analyses were also conducted to simulate the cutting steps of the destructive laboratory procedure. The residual stress distributions obtained by the back-computation procedure were then compared with the reference stress solutions provided by the finite element model. The comparisons show agreement and indicate that good results can be expected from the experimental method when it is applied to a pipe that has been subjected to a residual stress improvement process, provided that the axial gradient of stress is not too large.« less