Modulation of the LaFeO3 film growth by the terrace width of SrTiO3 substrates

Abstract

We have investigated the growth of polar LaFeO3 thin films on SrTiO3 (001) substrates with various terrace widths by pulsed laser deposition. It is found that the growth of LaFeO3 films undergoes a transition from a two-dimensional (2D) mode to a three-dimensional (3D) mode due to polarity compensation. Notably, however, the critical thickness of the growth mode transition from 2D to 3D can be modulated by the terrace width of the substrate, i.e., when the film is 30 monolayers thick, it becomes 3D growth on the substrates with narrow terrace width (∼100 nm) while it maintains 2D growth on those with wide terrace width (∼400 nm). Combined with dynamic and kinetic models, we have found that the modulation of the critical thickness from 2D to 3D is rationalized as a result of competition between the dynamic process and the kinetic process. These findings highlight the key influence of substrate surface morphology on the epitaxial growth of complex oxide films, shedding light on the construction of multifunctional artificial low-dimensional structures with polar stackings.