| Co-Investigator(Kenkyū-buntansha) |
IMADA Go Nagaoka University of Technology, Faculty of Engineering, Research Associate, 工学部, 助手 (60262466)
JIANG Weihua Nagaoka University of Technology, Faculty of Engineering, Lecturer, 工学部, 講師 (90234682)
MASUGATA Katsumi Nagaoka University of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (80157198)
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| Research Abstract |
By using intense pulsed ion-beam evaporation (BE) technique, which was invented by us in 1988, the preparation of perovskite type of ferroelectric materials (Ba_X, Sr_<1-X>) TiO_3 (hereafter, referred to BST) has been carried out as well as the elucidation of depositing process. The following conclusions were obtained.
(1) Previous method of frontsidw IBE (FS/IBE) has been revised to backside IBE (BS/IBE), where the substrate is placed in the opposite side of the target holder. The preparation takes place by the indirect ablation plasma due to the surrounding wall. Excellent improvement has been achieved on the surface morphology, where no droplets exist. Electrical properties are improved as well.
(2) Deposition rate of-20nm/shot has been obtained. Although it is an order of magnitude less than the normal FS/IBE,it is still high than any other techniques such as rf sputtering or pulsed laser deposition techniques.
(3) Little dependence of the dielectric constant has been seen vs.frequency by BS/IBE,in contrast of strong dependent by FS/IBE,indicating significant reduction of the dielectric loss.
(4) The preparation of BST thin films has been succeeded by BS/IBE with good quality of dielectric properties, without heating the substrate, in a good vacuum. This is the first success all over the world.
(5) Very good stoichiometry has been obtained, where no depletion of the composition ratio exists between the target and the substrate.
(6) If we change the composition ratio (x) of Ba, it has been available to prepare any kinds of perovskite type of dielectric materials from SrTiO_3 (STO) of x=0, BST and BaTiO_3 (BTO) of x=1.
The dielectric constsnt of BST films strongly depends on the ratio ofx, and has a peak at x=0.5-0.7.
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