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Preparation of the Bi 12 SiO 20 thin films by the sol-gel method. Š. Kunej , A. Veber and D. Suvorov Advanced Materials Jožef Stefan Institute. Outline. Introduction Aim of work Experimental Results Sapphire Si/SiO 2 /TiO 2 /Pt Spinel MgAl 2 O 4 Conclusions.
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Preparation of the Bi12SiO20 thin films by the sol-gel method Š. Kunej, A. Veber and D. Suvorov Advanced Materials Jožef Stefan Institute
Outline • Introduction • Aim of work • Experimental • Results • Sapphire • Si/SiO2/TiO2/Pt • Spinel MgAl2O4 • Conclusions
“Bulk” Bi12SiO20* (5.5GHz): ’ = 37.6 Qxf = 8100 GHz f = -20 ppm/K Tsint. = 850°C Microwave technology (LTCC) Ag MINITURIZATION THIN FILMS Introduction SILLENITE * M. Valant, D. Suvorov; J. Am. Ceram. Soc., 84[12], 2900-904, 2001
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
TEOS + 2-ethoxyethanol Experimental: SOL-GEL Synthesis Bi(NO3)3·5H2O Vacuum drying 60°C/96h • Used chemicals: • Bismuth (III) nitrate • [Bi(NO3)3·5H2O] • Tetraethly orthosilicate • (TEOS) [Si(OC2H5)5] • Acetic acid • [CH3COOH] • Ethanolamine • [H2NCH2CH2OH] • 2-ethoxyethanol • [C2H5OCH2CH2OH] Acetic acid + Ethanolamine Bi(NO3) Bismuth complex solution Sol Spin-coating (5000 rpm) 4x Analytical methods: XRD SEM AFM Firing: 300-700°C/1h Pyrolysis: 220°C/2min
C / ( mol/l ) t / h 1.20 5 1.12 48 0.98 168 0.76 456 0.67 - Results Influence of solvent on gelation time :
Results: Sapphire Results: Sapphire Spin-coating: 4 x 5000 rpm Firing: 700°C/1h
d 400nm Results: Sapphire
Results: Si/SiO2/TiO2/Pt Spin-coating: 4 x 5000 rpm Firing: 700°C/1h
d 230nm Results: Si/SiO2/TiO2/Pt
Results: Spinel Spin-coating: 4 x 5000 rpm Firing: 700°C/1h
d 300nm Results: Spinel
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