Direct Nanoscale Analysis of Temperature-Resolved Growth Behaviors of Ultrathin Perovskites on SrTiO₃

Abstract

Revealing growth mechanism of a thin film and properties of its film-substrate interface necessarily require microscopic investigations on the initial growth stages in temperature- and thickness-resolved manners. Here we applied in situ scanning tunneling microscopy and atomic force microscopy to investigate the growth dynamics in homo- (SrTiO3) and hetero- (SrRuO3) epitaxies on SrTiO3(001). A comparison of temperature-dependent surface structures of SrRuO3 and SrTiO3 films suggests that the peculiar growth mode switching from a "layer-by-layer" to "step-flow" type in a SrRuO3 films arises from a reduction of surface migration barrier, caused by the change in the chemical configuration of the interface between the topmost and underlying layers. Island densities in perovskite epitaxies exhibited a clear linear inverse-temperature dependence. A prototypical study on island nucleation stage of SrTiO3 homoepitaxy revealed that classical diffusion model is valid for the perovskite growths.

Controlled Growth of Ceria Nanoarrays on Anatase Titania Powder: A Bottom-up Physical Picture

“…[5][6][7] Understanding the resultant structure-property relationships and developing methods to form diverse heterointerfaces on demand promise great potential for tuning chemical and physical properties. [8][9][10][11][12][13] Further progress will rely on systematic strategies for rational control of the growth and evolution of interfaces. This opens the broader potential for impact from breakthroughs in the growth of heterostructures.…”

Ex-situ atomic force microscopy on the growth mode of SrRuO 3 epitaxial thin film

“…[12] STM study also did not show any signs of SF growth during the initial deposition of SRO on STO. [19] While it is possible that the intermittent growth scheme might modify the growth mode, [32] consistent observations from at least three different experimental techniques allow us to apply the ex-situ AFM technique to general PLE of transition metal oxides. Second, we postulate that the SRO layer can be deposited as half-a-unit-cell unit.…”

“…5(II)). [19,30,31] When the TiO2 termination changes to SrO termination, another incomplete half u.c. (RuO2) layer starts to be deposited ( Fig.…”

“…In general, in-situ monitoring such as reflectivity high-energy electron diffraction 4 (RHEED) and scanning tunneling microscopy (STM) is used to investigate the growth kinetics of the epitaxial thin films. [6,[17][18][19] More recently, growth monitoring of thickness and optical properties is also realized using in-situ spectroscopic ellipsometry. [20,21] RHEED has been mostly used to observe the surface structure, thickness and control the growth rates in real time during a deposition.…”

“…[24,25] Specifically, the growth mode changes from LBL to SF, accompanying the surface termination switching from BO2 (RuO2) to AO (SrO) which was confirmed by RHEED monitoring and STM. [19] Such transition in the growth mode and surface termination atomic layer was explained based on the reduction of surface migration barrier which is related to the chemical configuration of the interface.…”