송여진 , 이종현 , 이석우 , 정덕영 *
Department of Chemistry-BK 21, SungKyunKwan Univ.
Selective deposition of iron oxide films on Self-assembled organic monolayers using micro
contact printing.
Introduction
In situ patterning of crystalline iron oxide thin layers has been achieved via microcontact printing (CP) and selective deposition. The CP was used to pattern surface of self-assembled organic monolayers(OTS, n-octadecyltrichlorosiloxane) on Si(100) substrate using an elastomeric stamp (PDMS). The aqueous solutions of ferric nitrate(or ferric chloride) were used for selective depositions which could be controlled by the various process parameters, e.g., solution concentration, temperature, and deposition time.
Scanning electron microscopy (SEM), X-ray diffration method and optical microscopy were used to characterize the patterned thin films and their crystal structures.
Iron oxidesIron oxidesIron oxides
SKKU Inoganic Material Lab.
Preparation of Iron oxides
magnetic recording materials
Fe3O4 (magnetite)
- Fe2O3 (maghemite) : metastable ferrimagnetic form
<<Magnetic oxides >>
: The properties of the films are largely dependent on film preparation methods and conditions.(Terminal functionality of SAMs can alter the surface’s reactivity
and physical characteristics)
Iron oxidesIron oxidesIron oxides
SKKU Inoganic Material Lab.
- Fe2O3 (hematite) : thermodynamically stable antiferromagnetic forprecursor of - Fe2O3 , Fe3O4
Silicon oil
Magnetic stirrer
wafer dipping
Chemical solution deposition (CSD)*
Iron oxidesIron oxidesIron oxides
Reduction under H2 (350~ 850°C)
Sonication (10-20 mins)
Experimental
SKKU Inoganic Material Lab.
Fe(NO3)3 (+ urea)
or FeCl3
aqueous soln. at 75C
Iron oxidesIron oxidesIron oxides
Ink solution
Si wafer
PDMS stamp
HO-Terminated
SAMs
Iron(lll) oxides
Iron metal
CP
Selective Deposition
Annealing (under H2)
(OTS in Hexane)
Surface
Si wafer
Si wafer
Si wafer
CSD*
-FeOOH(akaganetite)
Annealing
Fe3O4 (magnetite)Fe (iron metal)
Fe(NO3)3 soln. FeCl3 soln.
-Fe2O3 (hematite)
Fe3O4 (magnetite)Fe (iron metal)
CSD*
Annealing850C for 5hrUnder H2
850C for 5hrUnder H2
Outline
SKKU Inoganic Material Lab.
Iron oxidesIron oxidesIron oxides
1. Fe(NO3)3 soln.
SKKU Inoganic Material Lab.
SiO2
100m
Hematite(- Fe2O3)/OTS
SiO2
SiO2
200m
(- Fe2O3)
Hematite/OTS
SEM images
20m 20m
-Fe2O3/OTS
SiO2
850C for 5hrsunder H2 (about 2~3hrs)
Calcining
Iron oxidesIron oxidesIron oxides
1m
Thickness ~ 150nm
SiO2
Fe3O4)/OTS(Fe +
SKKU Inoganic Material Lab.
Fe(NO3)3 soln.
200nm
Fe3O4)/OTS(Fe +
100m
Iron oxidesIron oxidesIron oxides
1m100m
Akaganeite/OTSSiO2
2. FeCl3 soln.
(-FeOOH)
SKKU Inoganic Material Lab.
500m
100m
1m
SiO2
1m
(Magnetite + Iron)/OTS
Iron oxidesIron oxidesIron oxides
850C for 5hrsunder H2 (about 2~3hrs)
SKKU Inoganic Material Lab.
FeCl3 soln.
Calcining
(Fe3O4 +Fe)
Iron oxidesIron oxidesIron oxides
XRD
10 20 30 40 50 60 70
100
200
300
400
500
600
(024
)
(214
)
(116
)
(113
)
(104
)
(110
)
(012
)
10 20 30 40 50 60 70
-FeOOH (Akaganeite)-FeOOH (Akaganeite)- Fe- Fe22OO33(Hematite)(Hematite)
Annealing 850oC, 5hr (under H2)
Inte
nsi
ty
(Magnetite) + Fe (Iron)(Magnetite) + Fe (Iron) FeFe33OO44
SKKU Inoganic Material Lab.
from ferric nitrate from ferric chloride
2
2
Inte
nsi
ty
Inte
nsi
ty
2
AES (Auger Electron Spectroscopy) analysis
Particle(-FeOOH)/OTS
SiO2
A
B
Iron oxidesIron oxidesIron oxides
SKKU Inoganic Material Lab.
Coun
ts (E
dN
(E)/
dE)
Kinetic energy(eV)
A B
A
B
ConclusionIron oxidesIron oxidesIron oxides
SKKU Inoganic Material Lab.
Crystalline films of - Fe2O3 (or -FeOOH) were deposited onto SAMs (OTS)
from iron nitrate (or iron chloride) aqueous solution at 75oC for 2hrs.
Selective deposition was realized precipitates of iron oxide phases
from aqueous solutions at temperature below 100℃.
Subsequently, Fe3O4 and Fe were obtained by annealing under H2 at 850C
for 5hrs.
Acknowlegement
We acknowledge support by the Korean Science and Engineering
Foundation through Grant R02-2000-00065.
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