title: Strain evolution of each type of grains in poly-crystalline (Ba,Sr)TiO(3) thin films grown by sputtering.
abstract: The strain states of [111]-, [110]-, and [002]-oriented grains in poly-crystalline sputtered (Ba,Sr)TiO(3) thin films on highly [111]-oriented Pt electrode/Si substrates were carefully examined by X-ray diffraction techniques. Remarkably, [002]-oriented grains respond more while [110]- and [111]-oriented grains do less than the theoretically estimated responses, which is understandable from the arrangement of the TiO(6) octahedra with respect to the stress direction. Furthermore, such mechanical responses are completely independent of the degree of crystallization and film thickness. The transition growth temperature between the positive and negative strains was also different depending on the grain orientation. The unstrained lattice parameter for each type of grain was different suggesting that the oxygen vacancy concentration for each type of grain is different, too. The results reveal that polycrystalline (Ba,Sr)TiO(3) thin films are not an aggregation of differently oriented grains which simply follow the mechanical behavior of single crystal with different orientations.
authors.affiliation: WCU hybrid materials program, Department of Materials Science and Engineering, and Inter-university Semiconductor Research Center, Seoul National University , Seoul 151-744, Korea.
authors.forename: Woo Young
authors.initials: WY
authors.lastname: Park
authors.forename: Min Hyuk
authors.initials: MH
authors.lastname: Park
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Yoon
authors.forename: Jeong Hwan
authors.initials: JH
authors.lastname: Han
authors.forename: Jung-Hae
authors.initials: JH
authors.lastname: Choi
authors.forename: Cheol Seong
authors.initials: CS
authors.lastname: Hwang