Effects of (100)-textured LaNiO 3 Electrode on the Deposition and Characteristics of PbTiO 3 Thin Films Prepared by rf M
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Effects of (100)-textured LaNiO3 electrode on the deposition and characteristics of PbTiO3 thin films prepared by rf magnetron sputtering Chii-Ming Wu, Tian-Jue Hong, and Tai-Bor Wu Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, Republic of China (Received 23 October 1995; accepted 3 March 1997)
Highly (100)-oriented thin films of PbTiO3 were prepared on (100)-textured LNOyPtyTiySiO2ySi substrates by rf magnetron sputtering at temperatures >480 ±C, while randomly oriented PbTiO3 films were obtained on PtyTiySiO2ySi substrates. The textured LNO layer can help to control the orientation of PbTiO3 thin films, and reduce their surface roughness quite significantly. The dielectric constant (eT ) of PbTiO3 films deposited on LNO was lower than that of films on Pt and the dielectric loss (tan d) increased when a higher deposition temperature or longer time was used. The highly (100)-textured PbTiO3 films also showed different ferroelectric hysteresis characteristics, i.e., a higher coercive field and a lower remanent polarization, from that of randomly oriented films deposited on Pt.
I. INTRODUCTION
Preparation of ferroelectric thin films has attracted great attention in recent years for their important applications to integrated circuit (IC) memories and pyroelectric microsensors.1–3 Among various ferroelectric materials of interest, lead titanate (PbTiO3 ) is commonly studied because of its superior ferroelectric and pyroelectric properties.4,5 Because ferroelectrics are crystallographically anisotropic, much effort has been given to the growth of epitaxial or highly oriented films on lattice-matched, single-crystal-oxide substrates, e.g., MgO (100),6,7 for the fabrication of high-density integrated devices. However, the substrates of single crystal oxide are not compatible with the fabrication process of integrated circuits on Si. On the other hand, Ptbased metal films are often used as the bottom electrode for ferroelectric-integrated capacitors, but it is difficult to prepare highly oriented ferroelectric films on Pt. Moreover, it causes an unsatisfactory performance against fatigue of ferroelectric polarization.8 Metallicoxide electrodes are considered to be a better choice.9–11 LaNiO3 (abbreviated LNO, hereafter) is a perovskite-type metallic oxide,12,13 and successful preparation of epitaxial or textured LNO thin films on sapphire (001) or MgO (100) substrates by a spray-ICP (inductively coupled plasma) technique at temperatures .600 ±C have been reported.14,15 More importantly, it was also found in our previous studies that a highly (100)-textured LNO thin film with a resistivity of ,0.5 mV cm can be easily prepared on various substrates by rf magnetron sputtering at temperatures ranging from 200 to 500 ±C,16 and highly (100)-oriented 2158
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J. Mater. Res., Vol. 12, No. 8, Aug 1997
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Pb[(Mg1/3 Nb2/3 )12x Tix ]O3 17,18 and Pb(Zr0.53 Ti0.47 )O3 16,19 thin films were
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