Post on 10-Feb-2016
description
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 chamberNICKELOCENE 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)
Grow
th R
ate
(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 23.13Fe 27.30O 37.31C 12.27
Ni 2p
Fe 2pO 1s
C 1s
XPS Results
Shorter cycles (20 cycles, 18 seconds each)
Element
Atomic Conc. (%)
Ni 24.82Fe 28.81O 39.40C 6.97
Ni 2p
Fe 2pO 1s
C 1s
XPS Results
Co-Deposition
Element
Atomic Conc. (%)
Ni 26.50Fe 22.69O 30.29C 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 29.17Fe 22.11O 31.07C 17.65
Ni 2p
Fe 2p
O 1s
C 1s
Tnickelocene Tn-butylferrocene Treactor
60oC 60oC 400oC
XPS Results – Iron
700705710715720725730735740745750Binding Energy (eV)
Inte
nsity
(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
nsity
(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