Post on 09-Apr-2015
description
Glancing Angle DepositionGlancing Angle Deposition
Dhruv Pratap Singh(2008PHZ8058)
Under the supervision of Dr. J. P. Singh
Department of Physics Indian Institute of Technology Delhi, New Delhi, India-110016
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Glancing Angle Deposition Glancing Angle Deposition (GLAD)(GLAD)
Schematic of GLAD
It is is a physical vapor deposition process where the
deposition flux is incident onto a substrate making a large angle
(θ) with respect to the surface normal and the substrate is
rotating in its azimuthal plane.
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Vapor source
substrate
θθ tilt in polar plane
Φ rotation in azimuthal plane
Substrate normal
flux
θθ β
Initial nucleation forms shadowing centers Columnar structures formed due to the shadowing effect
The empirical relation
between vapor incidence (θ)
angle and column tilt (β)angle is
tanβ= ½ tanθ.
Schematic of columnar growth in oblique angle deposition Schematic of columnar growth in oblique angle deposition
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(Brett M J et al , IEEE Transactions on Nanotechnology 2005, 4, 269)
1µm
Vapor flux
For θ = 65°
Interplay of surface diffusion and shadow effect occurs during columnargrowth.
Surface roughness
Flux
600nmSlanted silver nanorods for θ = 87°
Shadow region increases with
increase in incidence angle (θ)
which results in increase in
inter columnar separation and
hence the porosity of film
Increase in columnar growth with angle θ (Zhao et al, Proceedings of SPIE 2003, 5219, 59 ).
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200nm
(Dhruv P Singh et al, IIT Delhi)
Production of periodically structured thin film :Production of periodically structured thin film :
By growing artificial seeds (nucleation centers) we can grow the
columnar structures of desired distribution and periodicity.
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Growth of Si slantedposts over patternedsubstrate
1 µm(Ye et al, Nanotechnology 15, 2004, 817 ).
θ
Substrate normal
Vapor flux
seeds
Substrate(Brett M J et al , IEEE Transactions on Nanotechnology 2005, 4, 269)
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Effect of substrate rotation on columnar Effect of substrate rotation on columnar structuresstructures
Chevrons (zig-zag structures).
Vertical Post.
Helices (nanospring).
Multilayered columnar structures.
Chevrons 7(Brett M J et al , IEEE Transactions on Nanotechnology 2005, 4, 269)
ChevronsChevrons
180° rotation in azimuth plane
Normal to substrate
Columnar structure
substrate
Vapor source
Vapor flux
Zig-zag(chevrons) columns
θ
Substrate normalVapor flux (F)
Substrate
θ
Substrate
FF
F׀׀
Rotation in azimuth plane
Vertical posts
Substrate rotation
(Zhao et al, Proceedings of SPIE 2003, 5219, 59 ).
Vertical postsVertical posts
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Helices
Slow rotation
Substrate is rotated at very slow speed ( 0.07 to 0.20 rpm). Rotation is decided by deposition rate,
One pitch of helical column must grow in one substrate rotation.
One Pitch
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(Zhao et al, Proceedings of SPIE 2003, 5219, 59 ).
NanospringsNanosprings
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Multilayered nanostructures
By programming the stepping motor for different rotation speed
multilayered structures can be grown .
(Zhao et al, Proceedings of SPIE 2003, 5219, 59 ).
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Nano-structures
Deposition rate (Å/sec)
Oblique Angle
Substrate Rotation
( rpm )
Material –Substrate
Reference
Vertical post
4.0 86° 0.5 ZnO - Soda lime glass
Abraham Wolcott, Advanced functional mat. 2009, 19, 1849.
15 86° 0.22 Co – Si M. J. Brett, J. Vac. Sci. Technol. 1999, 17, 2671.
20 75° 0.64 Fe –Si(100) F. Liu, J. Appl. Phys. 1999, 85, 5486
Helices
3.0 87° 0.07 Si–SiO2 Ambarish Ghosh, Nanoletter 2009, 9, 2243
15.5 86° 0.12 Ti – Si M. J. Brett, J. Vac. Sci. Technol. 1999, 17, 2671.
20 75° 0.16 Fe –Si(100) F. Liu, J. Appl. Phys.1999, 85, 5486
Reported growth parameters for different Reported growth parameters for different nanostructuresnanostructures
QCM and Electric feed through ( on rear side)
Turbo molecular pump
Pirani gauge
Water cooled feed through
LT power supply
View port
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My deposition chamber (GLAD)
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