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Growth and Electrical Properties of Fe doped (Ba,Sr)TiO3 Thin Films Deposited by Pulsed Laser Deposition Yoshiyuki Yonezawa1, Megumi Kato1, Yoshinori Konishi1, Shizuyasu Yoshida1, Nobuhiro Okuda1, Takahiko Maeda1, Ryohei Tanuma1, Michio Ohsawa1, Hideaki Matsuyama1, Shinji Ogino1, Naoto Fujishima1, Akinori Matsuda1, Noboru Furusyo1, Toyohiro Chikyow2, Masashi Kawasaki3, Hideomi Koinuma4 1 Fuji Electric Corporate Research and Development, Ltd., Yokosuka, Japan 2 National Institute for Materials Science (NIMS), Tsukuba, Japan 3 Institute for Materials Research, Tohoku University, Sendai, Japan 4 Frontier Collaborative Research Center, Tokyo Institute of Technology, Yokohama, Japan ABSTRACT Impurity effects were investigated in (Ba,Sr)TiO3 (BST) systems in order to suppress leakage currents under relatively low oxygen pressure conditions by Pulsed Laser Deposition (PLD). We tried to dope transition metals, such as Mo, Mn, Cr, W and Fe into the BST target and used the targets to fabricate the films. By measuring electrical properties, we found Fe-doping had a significant effect on suppressing leakage current. Subsequently, we changed the amount of Fe doping from 0.1mol% to 6%. As a result, with post annealing, the sample with Fe:4% showed the lowest leakage current among those analyzed. Even without post annealing, the sample with Fe:6% showed the lowest leakage current. As for the dielectric constants, they decreased as the doping increased. At most, a 30% reduction was observed, compared with non-doped BST. XANES (X-ray Absorption Near Edge Structures) results indicated that the valency of the Fe ion was 3+ and located at the B-site of BST. INTRODUCTION (Ba,Sr)TiO3 is a good candidate for gate oxides and integrated capacitors because of its high dielectric constant and absence of lead content. Consequently, direct epitaxial growths of BST on Si substrates have been studied extensively[1,2]. However, there are problems with the formation of the SiO2 interlayer during deposition and leakage current due to the deficiency of oxygen. In particular, thin films deposited by PLD require more than 100 mtorr of oxygen partial pressure to obtain the required high break down voltage, which leads to the formation of the SiO2 interlayer. To suppress the leakage current we tried to dope transition metals into the target, such as Mo, Mn, Cr, W and Fe. Those doping effects have been studied extensively but most of the works have been carried out on sintered polycrystalline samples[3,4]. In C8.14.1

polycrystalline samples, the effects of grain boundaries could not be eliminated such as doped metal segregation. PLD(Pulsed Laser Deposition) is known for its capability to produce epitaxial single crystal like thin films. Investigating the films produced by PLD may enable us to understand the compensation mechanism of free carriers in doping methods. EXPERIMENTAL The BST target was prepared by sintering mixed powders of SrTiO3, BaTiO3 and 1mol% transition metal oxides such as Fe2O3, Cr2O3 at 1350oC. Nb-doped:SrTiO3 via step treatments was