Characterization of structure and current transport in BaTiO3 ultrathin films deposited on Nb:SrTiO3

• 作 者: Pan Ruikun Li Mingkai Liu Panke He Yunbin Tao Haizheng
• 机 构: School of Materials Science & Engineering,Hubei University,Wuhan 430062,P.R. China;State Key Laborat
• 出 处: 第十五届全国电介质、材料与应用学术会议
• 发表日期: 2014年5期

　　Recently BaTiO3(BTO)films have been a focus of intensive studies in Magnetoelectric coupling effect,ferroelectric tunnel junctions and artificial multiferroic tunnel junctions.In this paper 20 nm and 100 nm thick BTO films were prepared on Nb-doped SrTiO3(NSTO)single crystal substrates by the pulsed laser deposition(PLD)method.Surface morphology of the BTO films was measured by AFM,which shows smooth and uniform surfaces.XRD patterns with only(00l)separated peaks imply that the BTO films were hetero-epitaxially grown on the NSTO(001)substrates.HRTEM lattice image of the BTO/NSTO structure displays the epitaxial crystallographic relationship.P-V curves indicate that the polarization of BTO films becomes weaker with the decreasing of film thickness.Current-voltage(Ⅰ-Ⅴ)curves of the BTO films were measured at room temperature with Pt top electrodes deposited by sputtering.For 20 nm BTO film,Ⅰ-Ⅴ curves under reverse bias were excellently fitted by the Poole– Frenkel(P–F)emission and Fowler–Nordheim(F–N)tunneling mechanisms,respectively.At forward bias,the current was fitted by the space-charge-limited current(SCLC)mechanism.For 100 nm BTO film,Ⅰ-Ⅴ curves show rectifying behavior and can be well fitted by the SCLC mechanism under forward bias while thermionic emission model under reverse bias.Analysis indicates that a modulating Schottky barrier exists at the Pt/BTO interface,which dominates the current transport properties of BTO films.