Matjaž Spreitzer, Daniel Diaz, Tjaša Parkelj, Urška Gabor, Danilo Suvorov

Advanced Materials Department, Jožef Stefan Institute, Jamova 39, Ljubljana, Slovenia

Epitaxial integration of transition metal oxides with semiconductors brings a great number of exciting electrical, magnetic, and optical properties to the well-established silicon platform and represents a milestone for many novel device applications. A convenient way of integrating functional oxides with Si(001) substrate is through a SrTiO₃ (STO) intermediate layer, which has been grown in epitaxial form and with high crystallinity using molecular beam epitaxy (MBE) mainly. However, run-to-run stability of the MBE deposition process and difficult stoichiometry control makes this method inappropriate from an industrial point of view.

In this work we focused on the possibilities of using the pulsed-laser deposition (PLD) technique for the synthesis of functional layers on Si(001), as an alternative manufacturing route compared to MBE. First, metallic strontium was used to prepare (1×2)+(2×1) reconstructed Sr(1/2 ML)/Si(001) surface, which serves as a buffer material and hinders intense reaction of the constituents. For successful Si passivation unique structural analysis of the surface using Low Energy Electron Diffraction, Scanning Tunneling Microscopy, and X-ray Photoelectron Spectroscopy was introduced. Subsequently, detailed analysis of STO initial deposition parameters was performed, which enabled us to develop a complete protocol for integration, taking into account the peculiarities of the PLD process. The as-prepared oxide layer exhibits STO(001)||Si(001) out-of-plane and STO[110]||Si[100] in-plane orientation. In the final stage, piezoelectric Pb[Mg_1/3Nb_2/3]O₃-PbTiO₃ (PMN-PT) layer was integrated with as-prepared template. Due to its giant piezoelectricity in the thin film form PMN-PT represents a prime candidate for the active layer in microelectromechanical systems (MEMS), which integration with Si will also be discussed in the presentation.