Preparation of the Bi12SiO20 thin films by the sol-gel method

Š. Kunej, A. Veber and D. Suvorov

Advanced MaterialsJožef Stefan Institute

Outline

• Introduction• Aim of work• Experimental• Results

• Sapphire

• Si/SiO2/TiO2/Pt

• Spinel MgAl2O4

• Conclusions

Introduction

SILLENITESILLENITE

MINITURIZATION

THIN FILMSTHIN FILMS

* M. Valant, D. Suvorov; J. Am. Ceram. Soc., 84[12], 2900-904, 2001

AgAg

“Bulk” Bi Bi1212SiOSiO2020*

(5.5GHz):

’ = 37.6

Qxf = 8100 GHz

f = -20 ppm/K

Tsint. = 850°C

Microwave technology

(LTCC)

Aim of work

• Preparing Bi12SiO20 (BSO) thin films using sol-gel method

• Determining microstructure and thickness of BSO thin films deposited on substrates:– Sapphire

– Si/SiO2/TiO2/Pt

– Spinel MgAl2O4

Experimental: SOL-GEL Synthesis

Used chemicals:Used chemicals:•Bismuth (III) nitrate

[Bi(NO3)3·5H2O]•Tetraethly orthosilicate

(TEOS) [Si(OC2H5)5]•Acetic acid

[CH3COOH]•Ethanolamine

[H2NCH2CH2OH]•2-ethoxyethanol

[C2H5OCH2CH2OH]

Vacuum drying

60°C/96h

Bi(NOBi(NO33

))

Acetic acid+

Ethanolamine

Bismuth Bismuth complex complex solutionsolution

SolSol

Bi(NOBi(NO33))33·5H·5H22

OO

Spin-Spin-coating coating (5000 rpm)

Firing:

300-700°C/1h

TEOSTEOS +2-

ethoxyethanol

Analytical methods:Analytical methods:

XRD XRD SEM SEM AFM AFMPyrolysis: 220°C/2min

4x4x

Results

C / ( mol/l ) t / h

1.20 5

1.12 48

0.98 168

0.76 456

0.67 -

050

100150200250300350400450500

0,5 0,6 0,7 0,8 0,9 1 1,1 1,2 1,3

c ( mol/L )

time o

f gela

tion (

h )

Influence of solvent on gelation time :

Results: SapphireResults: Sapphire

Spin-coating: 4 x 5000 rpm

Firing: 700°C/1h

Results: Sapphire

d 400nm

Results: Si/SiO2/TiO2/Pt

Spin-coating: 4 x 5000 rpm

Firing: 700°C/1h

Results: Si/SiO2/TiO2/Pt

d 230nm

Results: Spinel

Spin-coating: 4 x 5000 rpm

Firing: 700°C/1h

Results: Spinel

d 300nm

Conclusions• The Bi12SiO20 (BSO) thin films were successfully

prepared by the sol-gel method• The BSO thin film obtained on sapphire substrate is

porous with rough surface• Homogeneous BSO thin film of thickness 230nm was

obtained for the thin film deposited on Si/SiO2/TiO2/Pt substrate

• Thin film deposited on the spinel substrate shows homogeneous microstructure with grain size of 200-500nm.

Future work:• Optimization of BSO sol-gel precursor• Obtaining “denser” BSO thin films • Dielectric measurements of BSO thin films