Atomic Structure Of Epitaxial Thin Films Of The Srn+1tinO3n+1 Ruddlesden-Popper Homologous Series

Abstract

The n+1TinO3n+1 Ruddlesden-Popper homologous series are promising candidates in the search for low loss tunable dielectric materials. SrTiO3 (n=∞) has the perovskite structure with alternating TiO2 and SrO layers. However, those members of the n+1TinO3n+1 series with n≠∞ have tetragonal symmetry and space group 14/mmm. These phases are formed by inserting a rock-salt SrO layer every n SrTiO3 perovskites, resulting in a successive perovskite blocks being mutually sheared by [1/2,1/2,0] (Fig. 1).Previously, the n = 1 - 3 members of this series have been made in polycrystalline form using solid state synthesis methods. Attempts to synthesize intermediate members (4≤n<∞) have been unsuccessful and resulted in mixed phase samples. Fortunately, significant advancement in epitaxial growth techniques makes it possible to control the synthesis of a wide variety of homologous oxide crystal systems. In the present work, thin films of the Srn+1TinO3n+1, RP series with n = 1 - 5 have been synthesized using reactive molecular beam epitaxy (MBE).