Download - INUP Talk 2011 Edited Palkar
-
8/10/2019 INUP Talk 2011 Edited Palkar
1/18
Realization of Multiferroic
anodevices
V. R. Palkar
Centre of Excellence in Nanoelectronics,
Indian Institute of Technology Bombay,Mumbai 400076, India
Acknowledgement: Mrinmoy
Mandal
(Ph.D
Student)Sriparna Chattergy (TIFR)
-
8/10/2019 INUP Talk 2011 Edited Palkar
2/18
Plan of the talk
Introduction to Multiferroics
Fabrication & Characterization
of BDFO nanorods
Conclusions
-
8/10/2019 INUP Talk 2011 Edited Palkar
3/18
Coexistence of ferroelectric & magnetic
ordering
Strain mediated ME coupling
Magnetization M E
Electric Polarization P B
Tremendous application potential
MEMS sensors & actuators, non-volatilememories, multiple memory elements etc.
Ferroelectrics distortion in latticePresence of magnetic element favors
structural symmetry
Scarcity of materials exhibit ing
ferroelectric & ferromagnetic ordering at RT
What are Multiferroics?
-
8/10/2019 INUP Talk 2011 Edited Palkar
4/18
1. V.R. Palkar et.al. J. Appl Phys., 93, 4337 (2003) Bi0.9La0.1Fe1-xMnxO3 (Bulk)
2. V. R. Palkar et al. Physical Review B 69, 212102 (2004) Bi0.9-xTbxLa0.1FeO3 (Bulk)
3. V. R. Palkar et al. Applied Physics Letters 84, 2856 (2004) Bi0.9-xTbxLa0.1FeO3 (TF)4. V. R. Palkar et al. J. Materials Research 22 (8), 2068 (2007) Bi0.9-xDyxLa0.1FeO3 (TF)
5.K. Prashanthi, V. R. Palkar et al. Solid State Commun. 2009 Bi0.7Dy0.3FeO3 (bulk, TF)
Development of novel room temperature
multiferroic
B based (Bi
0.7
Dy
0.3
FeO
3
) system
Bulk Pulse laser deposited Thin films on Si
-
8/10/2019 INUP Talk 2011 Edited Palkar
5/18
Realization of Multiferroic
Devices
(Nanorods and Bulk & micro inductors)Why multiferroic nanorod/wires ?
If multiferroic
properties could be fashioned in nanorods,
implementation in devices could be certainly more
efficient and straight forward
Growth of nano rod or wire like structure
Self organized growth during thermal processing
in rod/wire like structures (ZnO)
Electrolysis through template MOCVD
-
8/10/2019 INUP Talk 2011 Edited Palkar
6/18
Nanoporous
aluminatemplate
(pore diameter
80nm)
Pore diameter and
thickness controllable.
nanowires
grownthrough the template
Diameter same as the
pore size and length
of the nanowire
is
controllable.
nanowires
after
removal of the
template
nanowires
y electrodeposition
-
8/10/2019 INUP Talk 2011 Edited Palkar
7/18
Gold Tip
Deposition
AlloyDroplet
Gold Cluster PrecursorVapours
Annealing WhiskerGrowth
1 2 3 4
Vapour-Liquid-Solid Growth Technique
50000 X
500 nm
Cross sectional view
Top view
Growth of Nanowires
using MOCVD
SEM of NanoWires
-
8/10/2019 INUP Talk 2011 Edited Palkar
8/18
Tilted view 45 angle view
Failure in growing BDFO nanorods
through
porous alumina
template using PLD
Top surface of porous Alumina
template
BDFO deposited using PLD on
Alumina template
Cross sectional view
-
8/10/2019 INUP Talk 2011 Edited Palkar
9/18
Si nanorod (VLS route)
Au
Si
Au-Si
Au-Si
AuSi
Au
SiH4
Si
Liquid phase alloy at eutectic
temp of 400C
Nucleation Nano-rod growth
Termination of growth
SiH4
Au catalyst
ZnO nanorod (Aq. Solution route)
Si
was mounted in up side down position inside anordinary screw-cap pyrex
glass bottle.
Aqueous solution of zinc nitrate (Zn(NO3
)2
.6H2
O)
of strength 0.01M was used as a source of zinc ion.
Hexamethylenetetramine (HMT, (CH2
)6
N4
) of
strength 0.01M was used both as hydrolyzing and
capping agent.
Each sample was kept at 90C for 12 hours andthen cooled down to room temperature
After the reaction was over, samples were
thoroughly washed with de-ionized water until the
pH of the wash became
6.5.
SiH4
200 nm 2 um
J. Vac. Sci. Technol. B 15, 554 (1997) J. Nanoscience Nanotech. 9 (2009) 4792.
Grow th process for
rowth process for
Si
i
ZnO
nO
nanorod
anorod
BDFO S & Z O
-
8/10/2019 INUP Talk 2011 Edited Palkar
10/18
BDFO/Si rodsBDFO/Si rods
BDFO/ Si nano-rod
PLD
Parameters
Optimized
conditions
Laser density attarget
2.6 J/cm2
Target to substrate
distance
4.5 cm
Substrate
temperature
690C
Oxygen pressure 420 mTorr
Repetition rate 10 Hz
SEM image of Si rod
BDFO coated on template Si & Zno rods.
- Diameter :~ 500-800nm
- Height :~ 3-5 m
(including diameter ~300nm of Si or ZnO rod )
BDFO/BDFO/ZnOZnO rodsrods
200 nm
100 nm
BDFO
ZnO
200 nm
ZnO rod BDFO/ZnO rod
Cross sectional view of BDFO/ZnO rod
Table 1.Atomic % of chemical elements present in BDFO/ZnO
rods
grown on Si substrate
O Si Fe Zn Dy Bi
51.65 21.13 7.38 12.51 1.83 5.5
BDFO nanorods
using Si
& ZnO
nanorods
as core
-
8/10/2019 INUP Talk 2011 Edited Palkar
11/18
BDFO/Si rodsBDFO/Si rods BDFO/BDFO/ZnOZnO rodsrods
20 30 40 50 600
Intensity(arb.units)
2 Theta
S
i
Si
BDFO+Go
ld
BDFO+Gold
Si
BDFO
(a)
20 30 40 50 600
150
300
450
BDFO
ZnOZ
nO
BDFO
Intensi
ty
(arb.units)
2 Theta
BDFO
ZnO
XRD of BDFO/Si
BDFO/ZnO
nanorods
-
8/10/2019 INUP Talk 2011 Edited Palkar
12/18
Two point contact
Single point contact
BDFO/Si rodsBDFO/Si rods BDFO/BDFO/ZnOZnO rodsrods
Metallic probe
SiO2
Conductive Si
BDFO/ZnO rod
Metallic probe
Top electrode
W deposition
Lithographically defined electrical
ithographically defined electrical
contact
ontact
-
8/10/2019 INUP Talk 2011 Edited Palkar
13/18
-4 -2 0 2 4
M(
emu)
Magnetic Field (KOe)
BDFO/Si rods
-0.010 -0.005 0.000 0.005 0.010-10.0
-5.0
0.0
5.0
10.0
Polar
ization(C/cm
2)
Applied Voltage (V)
Without Magnetic Field
With magnetic Field (60 Oe)
-0.4 -0.2 0.0 0.2 0.4
-10
0
10
Polarization(uC
/cm
2)
Voltage Applied (V)
BDFO/Si rods
Comparison of multiferroic
properties
BDFO/Si BDFO/ZnO
M(emu)
-
8/10/2019 INUP Talk 2011 Edited Palkar
14/18
Electromagnetic coupling behavior of
lectromagnetic coupling behavior of
BDFO/
DFO/
Si
i
BDFO/
BDFO/
ZnO
nO
nanorods
anorods
using MAFM
sing MAFM
Effect of voltage on magnetic domain
structure
Topography MFM Phase at 0V MFM Phase at 2V
MFM Phase at 6V MFM Phase at 8V MFM Phase at 10V
Topoography 0V Topoography 4V Topoography 8V
MFM Phase 0V MFM Phase 4V MFM Phase 8V
BDFO/Si
nanorods
BDFO/ZnO
nanorods
-
8/10/2019 INUP Talk 2011 Edited Palkar
15/18
Piezoresponse
iezoresponse
behavior of
ehavior of
BDFO/
DFO/
Si
i
BDFO/
BDFO/
ZnO
nO
nanorods
anorods
% contraction in rod dimensions (nm) resulted due to applied voltage is
calculated from AFM images usingWSxM & Olympus analyzing software
0 2 4 6 8 10-2.5
-2.0
-1.5
-1.0
-0.5
0.0
%c
ontraction
Applied Voltage (V)
BDFO/Si rod
M. Mandal
and V. R. Palkar, Materials Research Soc. 2010
M. Mandal, S. Chattarjee and V. R. Palkar, Journal of Appl. Phys. 111, 45313, 2011
-
8/10/2019 INUP Talk 2011 Edited Palkar
16/18
ZnO
Bi0.7Dy0.3FeO3
Si
Bi0.7Dy0.3FeO3
Interfac
iallayer
Cross sectional Study
(a) (b)
TEM images revealing interface of
(a) BDFO/Si
& (b) BDFO/ZnO
nanorods
-
8/10/2019 INUP Talk 2011 Edited Palkar
17/18
Successfully grown multiferroic
BDFO nanorods
using
Si
& ZnO
nanorods
as core material
Ferroelectric properties and coupling coefficient of
BDFO/ZnO
nanorods
are much superior compared toBDFO/Si
nanorods. This could be attributed to formation ofSiO2
like interface in case of BDFO/Si
nanorods
Even piezo
response of BDFO/ZnO
nanorods
is muchbetter. Piezoelectric properties of ZnO
could be acting as
booster
BDFO/ZnO
nanorods
could be directly used as electricity
generators in the electronic circuits more effectively than
ZnO
nanorods
Conclusions
-
8/10/2019 INUP Talk 2011 Edited Palkar
18/18
Thank You