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