송여진, 이종현, 이석우, 정덕영 * Department of Chemistry-BK 21, SungKyunKwan Univ....

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)



- Fe2O3 (hematite) : thermodynamically stable antiferromagnetic forprecursor of - Fe2O3 , Fe3O4

Silicon oil

Magnetic stirrer

wafer dipping

Chemical solution deposition (CSD)*


Reduction under H2 (350~ 850°C)

Sonication (10-20 mins)

Experimental


Fe(NO3)3 (+ urea)

or FeCl3

aqueous soln. at 75C


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



1. Fe(NO3)3 soln.


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


1m

Thickness ~ 150nm

SiO2

Fe3O4)/OTS(Fe +


Fe(NO3)3 soln.

200nm

Fe3O4)/OTS(Fe +

100m


1m100m

Akaganeite/OTSSiO2

2. FeCl3 soln.

(-FeOOH)


500m

100m

1m

SiO2

1m

(Magnetite + Iron)/OTS


850C for 5hrsunder H2 (about 2~3hrs)


FeCl3 soln.

Calcining

(Fe3O4 +Fe)


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


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



Coun

ts (E

dN

(E)/

dE)

Kinetic energy(eV)

A B

A

B

ConclusionIron oxidesIron oxidesIron oxides


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.

송여진, 이종현, 이석우, 정덕영 * Department of Chemistry-BK 21, SungKyunKwan Univ....

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