The importance of annealing and stages coverage on the epitaxial growth of complex oxides on silicon by pulsed laser deposition

Abstract

The integration of epitaxial complex oxides with Si represents an invaluable opportunity for the creation of novel devices with logic and sensing capabilities, both implemented in the same chip. In this work, Pulsed Laser Deposition (PLD) is used to grow epitaxial ultra-thin (3–4 nm) SrTiO₃ (STO) layers on Si(001), showcasing the possibilities of this technique for the growth of templates for the integration of complex oxides with Si. Our procedure involves the growth of a 1/2 monolayer (ML) of Sr buffer layer on the reconstructed Si(001) surface by PLD, the deposition of STO in inert Ar atmosphere, and latter oxidation and crystallization phases. The optimization of STO deposition, oxidation, and crystallization parameters proves to be essential for the improvement of the layer's quality. It has been found that the minimization of the thermal budget during the crystallization phase increases the interface sharpness, but a minimum temperature is needed for a proper densification of the STO layer. A coverage of 2 ML before every crystallization and oxidation phases was determined as the best balance between the critical thickness, minimization of the thermal budget, and a proper coverage of the buffer layer, which prevents its reactions with the Sr/Si surface. These results improve the general knowledge and understanding of metal oxide/silicon heterojunctions, and represent a solid stepping stone for the growth of high-quality thin STO templates on Si by PLD.