1. Department of Chemistry-BK 21, SungKyunKwan Univ.
Selective deposition of iron oxide films on Self-assembled organic monolayers using microcontact printing.
송여진, 이종현, 이석우, 정덕영*
Department of Chemistry-BK 21, SungKyunKwan Univ.

2. Iron oxides
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.
SKKU Inoganic Material Lab.

3. - Fe2O3 (maghemite) : metastable ferrimagnetic form
Iron oxides
Preparation of Iron oxides
<<Magnetic oxides >>
- Fe2O3 (hematite) : thermodynamically stable antiferromagnetic for
precursor of  - Fe2O3 , Fe3O4
Fe3O4 (magnetite)
magnetic recording materials
- Fe2O3 (maghemite) : metastable ferrimagnetic form
: 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)
SKKU Inoganic Material Lab.

4. Experimental Chemical solution deposition (CSD)*
Iron oxides
Experimental
wafer dipping
Fe(NO3)3
(+ urea)
or FeCl3
aqueous soln. at 75C
Silicon oil
Magnetic stirrer
Chemical solution deposition (CSD)*
Sonication (10-20 mins)
Reduction under H2 (350~ 850°C)
SKKU Inoganic Material Lab.

5. Outline Fe(NO3)3 soln. FeCl3 soln. CSD* CSD* -FeOOH (akaganetite)
Iron oxides
Outline
PDMS stamp
Ink solution
(OTS in Hexane)
Fe(NO3)3 soln.
FeCl3 soln.
HO-Terminated
Si wafer
Surface
CP
CSD*
CSD*
SAMs
Si wafer
Selective Deposition
-FeOOH
(akaganetite)
-Fe2O3
(hematite)
Iron(lll) oxides
Annealing
Si wafer
850C for 5hr
Under H2
Annealing
850C for 5hr
Under H2
Annealing (under H2)
Iron metal
Fe3O4 (magnetite)
Fe (iron metal)
Fe3O4 (magnetite)
Fe (iron metal)
Si wafer
SKKU Inoganic Material Lab.

6. SEM images 1. Fe(NO3)3 soln. SiO2 SiO2 SiO2 Hematite/OTS
Iron oxides
SEM images
1. Fe(NO3)3 soln.
Hematite/OTS
Hematite(- Fe2O3)/OTS
(- Fe2O3)
SiO2
SiO2
SiO2
200m
100m
20m
20m
SKKU Inoganic Material Lab.

7. Calcining Fe(NO3)3 soln. -Fe2O3/OTS SiO2 (Fe + Fe3O4)/OTS
Iron oxides
Fe(NO3)3 soln.
(Fe +
Fe3O4)/OTS
Calcining
SiO2
850C for 5hrs
under H2 (about 2~3hrs)
100m
(Fe +
Fe3O4)/OTS
SiO2
Thickness ~ 150nm
-Fe2O3/OTS
200nm
1m
SKKU Inoganic Material Lab.

8. 2. FeCl3 soln. Akaganeite/OTS (-FeOOH) SiO2 500m 100m 1m
Iron oxides
2. FeCl3 soln.
500m
Akaganeite/OTS
(-FeOOH)
SiO2
100m
1m
SKKU Inoganic Material Lab.

9. Calcining FeCl3 soln. SiO2 (Magnetite + Iron)/OTS 850C for 5hrs
Iron oxides
FeCl3 soln.
Calcining
850C for 5hrs
under H2 (about 2~3hrs)
100m
SiO2
(Magnetite + Iron)/OTS
(Fe3O4
+Fe)
1m
1m
SKKU Inoganic Material Lab.

10. XRD - Fe2O3(Hematite) -FeOOH (Akaganeite)
Iron oxides
XRD
- Fe2O3(Hematite)
-FeOOH (Akaganeite)
from ferric nitrate
from ferric chloride
Intensity
Intensity 2 2
Annealing 850oC, 5hr (under H2)
(Magnetite) + Fe (Iron)
Fe3O4
Intensity 2
SKKU Inoganic Material Lab.

11. AES (Auger Electron Spectroscopy) analysis
Iron oxides
AES (Auger Electron Spectroscopy)
analysis A
Particle(-FeOOH)/OTS B A B
SiO2
Counts (E dN(E)/dE) A B
Kinetic energy(eV)
SKKU Inoganic Material Lab.

12. Conclusion Acknowlegement
Iron oxides
Conclusion
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 850C
for 5hrs.
Acknowlegement
We acknowledge support by the Korean Science and Engineering Foundation through Grant R
SKKU Inoganic Material Lab.