The Experts below are selected from a list of 23604 Experts worldwide ranked by ideXlab platform
Tushara Prakash - One of the best experts on this subject based on the ideXlab platform.
-
formatIon of magnetic nanoparticles by low energy dual implantatIon of ni and fe into sio2
Journal of Alloys and Compounds, 2016Co-Authors: Tushara Prakash, G V M Williams, J Kennedy, S RubanovAbstract:Abstract Magnetic nanoparticles have been made by Ni and Fe implantatIon into a SiO 2 film with a Ni:Fe ratio of 82:18 both before and after electron beam annealing (EBA). Superparamagnetic nanoparticles with diameters ∼4 nm were observed after implantatIon. The moment per Implanted Ion at high magnetic fields was significantly lower than that reported for bulk Ni 1− x Fe x with a similar x , which may be due to some Implanted Ions not magnetically ordering and the appearance of antiferromagnetic phases. The high field moment did not follow Bloch's T 3/2 law where T is the temperature. This behaviour is likely to be due to spin-waves propagating in the nanoparticle/Ni y Fe 1− y Si z O n matrix as well as the effect of disordered spins on the surfaces of the nanoparticles. After EBA, a bimodal size distributIon was observed with large isolated particles closer to the surface and smaller nanoparticles further into the film. Such a distributIon has not been previously reported for similar Fe or Ni implantatIon. All of the Ni and Fe moments have magnetically ordered and the high field moment can be modelled using Bloch's law and a small contributIon from disordered moments in the shell with an average thickness of ∼0.3 nm.
M Posselt - One of the best experts on this subject based on the ideXlab platform.
-
Ion beam induced atomic mixing in isotopically controlled silicon multilayers
Journal of Applied Physics, 2016Co-Authors: M Radek, H Bracht, Bartosz Liedke, Roman Bottger, M PosseltAbstract:ImplantatIon of germanium (Ge), gallium (Ga), and arsenic (As) into crystalline and preamorphized isotopically controlled silicon (Si) multilayer structures at temperatures between 153 K and 973 K was performed to study the mechanisms mediating Ion-beam induced atomic mixing. Secondary-Ion-mass-spectrometry was applied to determine concentratIon-depth profiles of the stable isotopes before and after Ion implantatIon. The intermixing is analytically described by a depth-dependent displacement functIon. The maximum displacement is found to depend not only on temperature and microstructure but also on the doping type of the Implanted Ion. Molecular dynamics calculatIons evaluate the contributIon of cascade mixing, i.e., thermal-spike mixing, to the overall observed atomic mixing. Calculated and experimental results on the temperature dependence of Ion-beam mixing in the amorphous and crystalline structures provide strong evidence for Ion-beam induced enhanced crystallizatIon and enhanced self-diffusIon, resp...
Jean Paul Allain - One of the best experts on this subject based on the ideXlab platform.
-
molecular dynamics studies of Ion beam implantatIon and patterning of silicon effect of noble gas cluster formatIon
Physical Review B, 2018Co-Authors: Michael A Lively, Samuel X Bennett, Jean Paul AllainAbstract:The use of energetic Ion beams to induce nanopattern formatIon at surfaces has been well studied both experimentally and theoretically. However, the influence on morphological evolutIon of the Implanted species themselves remains little understood, particularly in the case when the incident Ion species does not interact chemically with the target material. In this work, MD simulatIon results are presented for cumulative Ion bombardment of Si to a fluence of $3\ifmmode\times\else\texttimes\fi{}1{0}^{15}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$ or more for a range of incident Ion energies (20--1000 eV), angles ($0\ensuremath{-}{85}^{\ensuremath{\circ}}$), and species (Ne, Ar, Kr, Xe). For most cases, the Implanted Ions are observed to form gas clusters or bubbles beneath the surface as the fluence increases. The implantatIon and cluster formatIon decrease in magnitude with increasing Ion incidence angle, and remain fairly similar for the heavier-than-Si species (Ar, Kr, and Xe). However, the implantatIon and cluster formatIon are much more prominent for Ne irradiatIon. As the fluence continues to increase beyond $\ensuremath{\sim}1{0}^{15}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$, the gas clusters begin to become exposed to the vacuum as the Si layers trapping the gas atoms are eroded by the incident Ions. The exposed gas clusters then degas very rapidly, leading to disruptIon at the surface and to viscous material flow of Si into the void left behind. Comparison to dynamic binary collisIon approximatIon (BCA) simulatIons indicates that cluster formatIon and degassing contributes to a wide distributIon of single-impact emissIon yields of Implanted Ions, contrary to intuitive expectatIons based on BCA simulatIons. Notably, the increased size and frequency of many-atom Implanted Ion emissIon events contributes to a much lower concentratIon of the Implanted species than is otherwise expected from BCA simulatIons. AdditIonally, this cluster degassing phenomenon is conjectured to provide a potential ``antipatterning'' mechanism by disrupting or destroying nanopattern ``seeds'' at the surface. This could provide an additIonal mechanism to improve model predictIons of critical angles for patterning transitIons, and may also provide at least a partial explanatIon for the difficulty of obtaining patterns on Ne-bombarded Si surfaces.
S Rubanov - One of the best experts on this subject based on the ideXlab platform.
-
formatIon of magnetic nanoparticles by low energy dual implantatIon of ni and fe into sio2
Journal of Alloys and Compounds, 2016Co-Authors: Tushara Prakash, G V M Williams, J Kennedy, S RubanovAbstract:Abstract Magnetic nanoparticles have been made by Ni and Fe implantatIon into a SiO 2 film with a Ni:Fe ratio of 82:18 both before and after electron beam annealing (EBA). Superparamagnetic nanoparticles with diameters ∼4 nm were observed after implantatIon. The moment per Implanted Ion at high magnetic fields was significantly lower than that reported for bulk Ni 1− x Fe x with a similar x , which may be due to some Implanted Ions not magnetically ordering and the appearance of antiferromagnetic phases. The high field moment did not follow Bloch's T 3/2 law where T is the temperature. This behaviour is likely to be due to spin-waves propagating in the nanoparticle/Ni y Fe 1− y Si z O n matrix as well as the effect of disordered spins on the surfaces of the nanoparticles. After EBA, a bimodal size distributIon was observed with large isolated particles closer to the surface and smaller nanoparticles further into the film. Such a distributIon has not been previously reported for similar Fe or Ni implantatIon. All of the Ni and Fe moments have magnetically ordered and the high field moment can be modelled using Bloch's law and a small contributIon from disordered moments in the shell with an average thickness of ∼0.3 nm.
J Kennedy - One of the best experts on this subject based on the ideXlab platform.
-
formatIon of magnetic nanoparticles by low energy dual implantatIon of ni and fe into sio2
Journal of Alloys and Compounds, 2016Co-Authors: Tushara Prakash, G V M Williams, J Kennedy, S RubanovAbstract:Abstract Magnetic nanoparticles have been made by Ni and Fe implantatIon into a SiO 2 film with a Ni:Fe ratio of 82:18 both before and after electron beam annealing (EBA). Superparamagnetic nanoparticles with diameters ∼4 nm were observed after implantatIon. The moment per Implanted Ion at high magnetic fields was significantly lower than that reported for bulk Ni 1− x Fe x with a similar x , which may be due to some Implanted Ions not magnetically ordering and the appearance of antiferromagnetic phases. The high field moment did not follow Bloch's T 3/2 law where T is the temperature. This behaviour is likely to be due to spin-waves propagating in the nanoparticle/Ni y Fe 1− y Si z O n matrix as well as the effect of disordered spins on the surfaces of the nanoparticles. After EBA, a bimodal size distributIon was observed with large isolated particles closer to the surface and smaller nanoparticles further into the film. Such a distributIon has not been previously reported for similar Fe or Ni implantatIon. All of the Ni and Fe moments have magnetically ordered and the high field moment can be modelled using Bloch's law and a small contributIon from disordered moments in the shell with an average thickness of ∼0.3 nm.
