Ion Implantation
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Transcript of Ion Implantation
E.M. Hunt , J.M. Hampikian , D.B. Poker , N.D. Evans
Ion implantation induced formation of aluminum nanoparticles in
alumina via reduction
Presentation by: Younes Sina
Colloid formation mechanism:
Ion implantation
Precipitation of the implanted ion(s) & formation of nanocrystals at high temperature during implantation or post-implantation annealing Irradiation –induced dissociation of the host material
Metal particle formation due to electron or neutron irradiation of alkali halides (LiF), alkaline earth fluorides (CaF2), and some oxides (Lithia LiO, Alumina Al2O3)
LiF Li (colloid)slightly elevated temperature
eAl2O3
14 MeVAl
Al2O3thin film
1 MeV
elevated temperature
Al LiO2 Li (colloid)
1 MeVe
e
e
Removing residual polishing damage
1500 ⁰C
80 h
Vacuum
0.5-2 mA
1x10-7 Torr
50 keV
70 keV
5x1016 Ca+/cm2
Vacuum
0.5-2 mA
1x10-7
150 keV
5x1016 Y+/cm2
Equipments used for the results:
Knoop microhardness
Rutherford backscattering
Differential optical absorption
TEM
Energy Dispersive X-ray Spectroscopy (EDS)
High Resolution Parallel detector Electron Energy Loss Spectroscopy (PEELS)
Energy Filtered TEM (EFTEM)
Ca 14%
Y 9%
Ca 10%
50 keV 70 keV ~30nm ~40 nm
~41 nm
150 keV
Experimental implanted ion range
Amorphous layer =120 nm
5x1016 Ca+/cm25x1016 Ca+/cm2
5x1016 Y+/cm2
Experimental im
planted ion range
Experimental im
planted ion range
Experimental im
planted ion range
The implanted ion range predictions made by PROFILE simulation program were reasonably accurate.
Rutherford backscattering
Knoop microhardness
<1
Ca 50
Ca 70
Y 1 50
Implanted hardness
Unimplanted hardness
Differential optical absorption by High Resolution TEM
Optical absorption spectra from the implanted samples, showing the absorption feature caused by the presence of metallic colloids dispersed in the matrix.
?
?
TEM
TEM micrograph of 150 keV Y+ implantation
TEM micrograph of 50 keV Ca+ implantation
TEM micrograph of 70 keV Ca+ implantation
10.7±1.8 nm
8.8±1.2 nm
7.5±1.4 nm
0.410±0.004 nm
0.413±0.004 nm
0.409±0.004 nm
Lattice parameter of pure FCC aluminum= 0.40497 nm
From: High Resolution Parallel detector Electron Energy Loss Spectroscopy (PEELS)
Energy loss spectra from 150 keV Y+
Energy loss spectra from 70 keV Ca+
Alumina Plasmon loss @ 25 eVMetallic aluminum Plasmon @ 15 eV
Energy Dispersive X-ray Spectroscopy (EDS)
Chemical analysis of the 3 samples using Energy Dispersive X-ray Spectroscopy (EDS) indicates that the particles are aluminum-rich with respect to the surrounding matrix.
There is no graph or more information about EDS !!!!!??????
Energy Filtered TEM (EFTEM) micrographs of the 50-keV Ca+ implantation
15-eV-loss image
25-eV-loss image
Elemental map of oxygen from an adjacent region
particles in the implanted areas appear bright
particles in the implanted areas appear dark
particles are oxygen deficient with respect to the surrounding matrix
This set of images confirms that the particles contain metallic aluminum
ωp =Plasmon frequency of the bulk metal
Wavelength at maximum absorption (λ peak) due to colloidal metal particles
width of absorption peak:
ω0 =Collision frequency of the electron in the metal
Mie theory for absorption by small metal particles
)2 200
(2 2/1
np
peak
c
)2(2
4 2
0020 np
c
From Eq. (1):
λ peak=218 nm using
ε₀=1 n0 =1.76ω₀ =2.309x1016 s-1
Implantation of ions into the matrix materials will increase the index of refraction (n0) in the surface region
Increase of n0 =1.76 to 1.96 results in a calculated λ peak=240 nm
Theoretical calculation:
Alumina is known to be difficult to fully amorphize except with large doses of heavy ions and/or implantation at reduced
temperatures
Zn & Zr (strongly oxidizing elements) produce buried amorphous layers in alumina with much greater accelerating energies or a much higher fluence.
Different behavior of Ca
?
Reduction of target cation with ion (that is more oxygen reactive)
2 Y+ Al2O3 2 Al+ Y2O3
3 Ca+ Al2O3 2Al+ 3CaO
G<0
G<0
Kurdistan, Iran