Mark Kimbell Prof. Takoudis Manish Singh Yi Yang.
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Transcript of Mark Kimbell Prof. Takoudis Manish Singh Yi Yang.
Chemical Vapor Deposition of NiFe2O4 using Nickelocene and N-butylferroceneMark KimbellProf. TakoudisManish Singh
Yi Yang
Project
Chemical Vapor Deposition Nickel Oxide (NiO) using Ni(C5H5)2
Iron Oxide (Fe2O3) using FeC14H18
Nickel Ferrite (NiFe2O4)▪ Choose appropriate conditions based on NiO
and Fe2O3 growth rates
▪ XPS to analyze chemical composition▪ XRD to analyze crystalline structure
Background
The magnetoelectric (ME) effect Ferroelectric and ferromagnetic coupling▪ Magnetic switching by an applied electric
field▪ Electric polarity switching by an applied
magnetic field
Magnetoelectric Materials
Uses Memory storage devices Tunable microwave devices Sensors Transducers
C Israel, ND Mathur & JF Scott, Nature Materials 7 (2008) 93
Magnetoelectric Composites
Magnetoelectric composites Made up of a piezoelectric
layer and a magnetostrictive layer
NiFe2O4
Chemical Vapor Deposition (CVD)
Argon gas
Oxygen gas
Quartz tube
Heater
Vacuum pump
Substrate
Precursors
Source of the vapor which is fed into the reaction chamber
NICKELOCENE
Ni(C5H5)
2
N-BUTYLFERROCENE
C14H18Fe
8
Nickel Oxide Data
Nickel Oxide Growth Rate(Reactor = 400 oC)
Temperature of Nickelocene (oC)
9
Iron Oxide Data
Temperature of N-Butylferrocene (oC)
Gro
wth
Rate
(nm
/min
)
Iron Oxide Growth Rate(Reactor = 500 oC)
Important Results
Treactor = 400oC Tnickelocene = 60oC
Treactor = 400oC Tn-butylferrocene =
65oC
NiO growth rate = 4.6 nm/min
Fe2O3 growth rate = 8.5 – 9 nm/min
The Plan
CyclesTnickelocene Tn-butylferrocene Treactor NiO deposition time (s) Fe2O3 deposition time (s) Cycles60 65 400 60 30 560 65 400 12 6 20
Co-depositionTnickelocene Tn-butylferrocene Treactor Deposition time (min)60 65 400 1060 60 400 10
X-Ray Photoelectron Spectroscopy (XPS)
Uses x-rays to knock electrons free from surface
Measures kinetic energy of electrons to determine chemical composition
http://www.sckcen.be/microstructure/Infrastructure/XPS/Infrastructure_XPS.htm
XPS Results
Longer cycles (5 cycles, 90 seconds each)
Element
Atomic Conc. (%)
Ni 23.13
Fe 27.30
O 37.31
C 12.27
Ni 2p
Fe 2pO 1s
C 1s
XPS Results
Shorter cycles (20 cycles, 18 seconds each)
Element
Atomic Conc. (%)
Ni 24.82
Fe 28.81
O 39.40
C 6.97
Ni 2p
Fe 2pO 1s
C 1s
XPS Results
Co-Deposition
Element
Atomic Conc. (%)
Ni 26.50
Fe 22.69
O 30.29
C 20.52
Ni 2p
Fe 2p
O 1s
C 1s
Tnickelocene Tn-butylferrocene Treactor
60oC 65oC 400oC
XPS Results
Co-Deposition
Element
Atomic Conc. (%)
Ni 29.17
Fe 22.11
O 31.07
C 17.65
Ni 2p
Fe 2p
O 1s
C 1s
Tnickelocene Tn-butylferrocene Treactor
60oC 60oC 400oC
XPS Results – Iron
700705710715720725730735740745750
Binding Energy (eV)
Inte
nsi
ty (
a. u
.)
Peaks correspond to Fe(III) oxidation state
* S. A. Chambers, Y. J. Kim, and Y. Gao Surf. Sci. Spectra 5 219 (1998)
*
XPS Results – Nickel
840850860870880890900
Binding Energy (eV)
Inte
nsi
ty (
a. u
.)
* A. N. Mansour, Surf. Sci. Spectra 3 231 (1994)
Peaks correspond to Ni(II) oxidation state
*
XPS Results
Do not indicate the presence of NiFe2O4
Probably due to interactions between the two gases
Presence of carbon From atmosphere▪ Argon sputtering
From unreacted precursor▪ Due to relatively low deposition temperature
Summary
XPS revealed the presence of both Ni(II) and Fe(III)
The ratio of Ni to Fe did not indicate NiFe2O4
Different deposition conditions must be used in order to achieve the correct ratios Higher reactor temperature Higher iron precursor temperature Lower nickel precursor temperature
Future Work
Try different deposition conditions to deposit NiFe2O4 thin films
X-ray diffraction (XRD) on NiFe2O4 thin films to determine crystalline structure
Anneal to reduce carbon contamination, correct defects / change crystal structure
References
E. Ascher, H. Rieder, H. Schmid, and H. Stössel, J. Appl. Phys. 37 (1966) 1404
W. Eerenstein, N. D. Mathur and J. F. Scott, Nature 442, (2006) 759-765
A.M.J.G. Van Run, D.R. Terrell, and J.H. Scholing, Journal of Materials Science 9 (1974) 1710-1714
W. Yeh and M. Matsumura, Jpn. J. Appl. Phys. Vol. 36 (1997) Pt. 1, No. 11
M. Singh, Y. Yang, and C.G. Takoudis, Journal of The Electrochemical Society, 155 (9) (2008) D618-D623
S.A. Chambers, Y.J. Kim, and Y. Gao, Surf. Sci. Spectra 5 (1998) 219
S. Oswald and W. Bruckner, Surf. Interface Anal. 36 (2004) 17–22
http://www.sckcen.be/microstructure/Infrastructure/XPS/Infrastructure_XPS.htm
Acknowledgements
EEC-NSF Grant # 0755115 Dr. Christos Takoudis Graduate students: Yi Yang, Manish
Singh, Qian Tao
Questions?
Cycling
Argon gas
Oxygen gas
Quartz tube
Heater
Vacuum pump
Substrate
Cycling
Co-Deposition
Argon gas
Oxygen gas
Quartz tube
Heater
Vacuum pump
Substrate
Co-Deposition
Experiment – Setup
Temperaturecontrollers
Precursorcontainers
Reaction chamber
Cold trap
Vacuum pump
• nickelocene• n-butylferrocene
Ellipsometer
Used to measure film thickness
Light source
Polarizer SampleAnalyzer
Θ