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Mark Kimbell Prof. Takoudis Manish Singh Yi Yang
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Chemical Vapor Deposition Nickel Oxide (NiO) using Ni(C 5 H 5 ) 2 Iron Oxide (Fe 2 O 3 ) using FeC 14 H 18 Nickel Ferrite (NiFe 2 O 4 ) ▪ Choose appropriate conditions based on NiO and Fe 2 O 3 growth rates ▪ XPS to analyze chemical composition ▪ XRD to analyze crystalline structure
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The magnetoelectric (ME) effect Ferroelectric and ferromagnetic coupling ▪ Magnetic switching by an applied electric field ▪ Electric polarity switching by an applied magnetic field
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Uses Memory storage devices Tunable microwave devices Sensors Transducers C Israel, ND Mathur & JF Scott, Nature Materials 7 (2008) 93
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Magnetoelectric composites Made up of a piezoelectric layer and a magnetostrictive layer NiFe 2 O 4
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Argon gas Oxygen gas Quartz tube Heater Vacuum pump Substrate
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Source of the vapor which is fed into the reaction chamber NICKELOCENE Ni(C 5 H 5 ) 2 N-BUTYLFERROCENE C 14 H 18 Fe
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Nickel Oxide Data 8 Nickel Oxide Growth Rate (Reactor = 400 o C) Temperature of Nickelocene ( o C)
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9 Iron Oxide Data Temperature of N-Butylferrocene ( o C) Growth Rate (nm/min) Iron Oxide Growth Rate (Reactor = 500 o C)
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T reactor = 400 o C T nickelocene = 60 o C T reactor = 400 o C T n-butylferrocene = 65 o C NiO growth rate = 4.6 nm/min Fe 2 O 3 growth rate = 8.5 – 9 nm/min
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Cycles T nickelocene T n-butylferrocene T reactor NiO deposition time (s)Fe 2 O 3 deposition time (s)Cycles 606540060305 606540012620 Co-deposition T nickelocene T n-butylferrocene T reactor Deposition time (min) 606540010 60 40010
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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
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Longer cycles (5 cycles, 90 seconds each) ElementAtomic Conc. (%) Ni23.13 Fe27.30 O37.31 C12.27 Ni 2p Fe 2p O 1s C 1s
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Shorter cycles (20 cycles, 18 seconds each) ElementAtomic Conc. (%) Ni24.82 Fe28.81 O39.40 C6.97 Ni 2p Fe 2p O 1s C 1s
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Co-Deposition ElementAtomic Conc. (%) Ni26.50 Fe22.69 O30.29 C20.52 Ni 2p Fe 2p O 1s C 1s T nickelocene T n-butylferrocene T reactor 60 o C65 o C400 o C
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Co-Deposition ElementAtomic Conc. (%) Ni29.17 Fe22.11 O31.07 C17.65 Ni 2p Fe 2p O 1s C 1s T nickelocene T n-butylferrocene T reactor 60 o C 400 o C
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Peaks correspond to Fe(III) oxidation state * S. A. Chambers, Y. J. Kim, and Y. Gao Surf. Sci. Spectra 5 219 (1998) *
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* A. N. Mansour, Surf. Sci. Spectra 3 231 (1994) Peaks correspond to Ni(II) oxidation state *
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Do not indicate the presence of NiFe 2 O 4 Probably due to interactions between the two gases Presence of carbon From atmosphere ▪ Argon sputtering From unreacted precursor ▪ Due to relatively low deposition temperature
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XPS revealed the presence of both Ni(II) and Fe(III) The ratio of Ni to Fe did not indicate NiFe 2 O4 Different deposition conditions must be used in order to achieve the correct ratios Higher reactor temperature Higher iron precursor temperature Lower nickel precursor temperature
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Try different deposition conditions to deposit NiFe 2 O 4 thin films X-ray diffraction (XRD) on NiFe 2 O 4 thin films to determine crystalline structure Anneal to reduce carbon contamination, correct defects / change crystal structure
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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
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EEC-NSF Grant # 0755115 Dr. Christos Takoudis Graduate students: Yi Yang, Manish Singh, Qian Tao
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Argon gas Oxygen gas Quartz tube Heater Vacuum pump Substrate Cycling
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Argon gas Oxygen gas Quartz tube Heater Vacuum pump Substrate Co-Deposition
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Temperature controllers Precursor containers Reaction chamber Cold trap Vacuum pump nickelocene n-butylferrocene
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Used to measure film thickness Light source Polarizer Sample Analyzer Θ
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