Sains Malaysiana 37(3): 261-264(2008)

Effect of Annealing Temperature on the Microstructure and Dielectric Properties of Ba0.6Sr0.4TiO3 Thin Films Prepared by Sol-Gel Process
(Kesan Suhu Sepuh Lindap ke atas Mikrostruktur dan Sifat Dielektrik
Filem Nipis Ba0.6sr0.4TiO3 yang disediakan dengan Proses Sol-Gel)

R. Dewi, N.B. Ibrahim, I.A. Talib & Z. Ibarahim
School of Applied Physics, National University of Malaysia
43600 UKM Bangi, Selangor, Malaysia

Received: 12 June 2007 / Accepted: 4 December 2007

ABSTRACT

Thin films of barium strontium titanate (Ba0.6Sr0.4TiO3) perovskite system are promising candidates for microelectronic devices that can be integrated with semiconductor technology. Ba0.6Sr0.4TiO3 thin films have been prepared onto BST/TiO2/RuO2/SiO2/Si substrate using the spin coating and sol-gel process. Then the samples were subsequently annealed at 600oC, 650oC and 700oC for 60 minutes in air. The microstructure and dielectric properties show that the crystallization improved as the annealing temperature was increased. All of the films have nanometer grain size. The average grain size of the films increased as the temperature was increased. The dielectric constant and ac conductivity of the films also increased as the average grain size increased. These results showed that the microstructure and dielectric properties depend on the annealing temperature.

Keywords: BST thin films; sol-gel process; dielectric constant; electrical conductivity

ABSTRAK

Filem nipis perovskit barium strontium titanate (Ba0.6Sr0.4TiO3) adalah sistem yang berpotensi digunakan untuk peranti mikroelektronik yang merupakan gabungan daripada teknologi semikonduktor. Filem nipis Ba0.6Sr0.4TiO3 telah dibuat di atas substrat BST/TiO2/RuO2/SiO2/Si menggunakan salutan berputar dan proses sol-gel. Kemudiannya sampel ini disepuh lindap pada suhu 600oC, 650oC dan 700oC selama 60 min dalam udara. Mikrostruktur dan sifat dielektrik yang telah dikaji menunjukkan struktur hablur yang semakin baik dengan peningkatan suhu sepuh lindap. Semua filem mempunyai saiz butiran nanometer. Purata saiz butiran meningkat dengan peningkatan suhu. Nilai pemalar dielektrik dan ac konduktiviti daripada filem juga turut meningkat dengan pertambahan purata saiz butiran. Hasil ini memperlihatkan bahawa mikrostruktur dan sifat dielektrik berpengaruh pada suhu sepuh lindap.

Kata kunci: Filem nipis BST; proses sol-gel; pemalar dielektrik; kekonduksian elektrik

RUJUKAN/REFERENCES

Chen, H., Yang, C., Fu, C., Zhao, L., Gao, Z. 2006. The size effect of Ba0.6Sr0.4TiO3 thin films on the ferroelectric properties. J. Appl. Surface. Sci. 252: 4171-4177.

Chu, C.M. & Lin, P., 1997. Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron Sputtering. J. Appl. Phys. Lett. 70: 249-251.

Chu, C.M. & Lin, P. 1998. Electrical properties and crystal structures of (Ba,Sr) TiO3 films and BaRuO3 bottom electrodes prepared by sputtering. J.Appl.Phys.Lett. 72: 1241-1243.

Ezhilvalavan, S & Tseund, Y.T. 2000. Progress in the developments of (Ba,Sr)TiO3 (BST) thin films for gigabit era DRAMS. Materials Chemistry and Physics. 65: 227-248. 

Horikawa,T., Mikami, N., Makita, T., Tanimura, J., Kataoka, M., Sato, K. & Nunoshita, M.,1993. Dielectric properties of (Ba,Sr)TiO3 thin films deposited by RF sputtering. Jpn. J. Appl. Phys. 32: 4126-4130.

Heywang, W & Thoman,H. 1991. Positive temperature coefficient resistors, in: Steele, B.C.H.(Eds.), Electronic Ceramics, London: Elsevier.

Liu, S., Liu, M., Zeng, Y., Li, C., Chen, S., Huang, Y., Xia, D., 2002. Preparation and characterization of Ba1-xSrxTiO3 thin films for uncooled infrared focal plane arrays. J.Mater. Sci. and Engineering C 22: 73-77.

Paik, D.S., Rao, A.V.P. & Komarneni, S., 1997. Ba titanate and barium/strontium titanate thin films from hydroxide precursors: preparation and ferroelectric behavior J. Sol-Gel Sci. and Tech. 10: 213-220.

Tian. H.Y., Luo. W.G., Ding. A.L., Choi. J., Lee. C, No. K. J. 2002. Influences of annealing temperature on the optical and structural properties of (Ba,Sr)TiO3 thin films derived from sol-gel technique. Thin Solid Films, 408: 200-205

Tsau, Y.M., Chen, Y.C., Cheng, H.F., Lin, I.N. 2001. Ferroelectric (Ba,Sr) TiO3 and Pb(Zr,Ti)O3 thin films prepared by pulsed laser deposition. J. Europ. Cer. Soc. 21: 1561-1564.

Wu, D., Li, A., Ling,H., Yin,X., Ge,C., Wang, M., Ming, N., 2000. Preparation of (Ba0.5Sr0.5) TiO3 thin films by sol–gel method with rapid thermal annealing. J. Appl. Surf. Sci. 165: 309-314.

Yan, F., Bao, P., Zang, Z., Zhu, J., Wang, Y., Chan, H.L.W., Choy, C.L., 2000. Dielectric properties of (Ba0.5Sr0.5 ) TiO3 thin films. J. Thin Solid Films 375: 184-187.

Zhu, H., Miao ,J., Noda, M & Okuyama, M. 2004. Preparation of BST ferroelectric thin film by metal organic decomposition for infrared sensor. Sensors and Actuators A 110: 371-377.

Zhang, T.J. & Ni, H. 2002. Fabrication and electrical properties of Ba0.64Sr0.36TiO3 thin films by sol-gel on platinum coated silicon. J.Mater.Sci 37: 4155-4158.

Zhu, H., Xu, H., Noda, M., Mukaigawa, T., Hashimoto, K., Okuyama, M., 2001. Preparation of BST ferroelectric thin film by metal organic decomposition for infrared sensor. J.T. IEE. 121-E: 308-312.