Critical issues of complex, epitaxial oxide growth and integration with silicon by molecular beam epitaxy

Molecular beam epitaxy was used to grow epitaxial oxides on silicon substrates. The growth of BaO, SrO, EuO, and SrTiO₃ are discussed with a focus on the general theme of integration of functional, epitaxial oxides into a silicon environment.; Oxidation studies of various metal systems relevant for oxide on silicon epitaxy and integration are reported. Results demonstrate the catalytic nature of an alkaline earth metal at small concentrations to enable the oxidation of the poorly oxidizing metals at pressures lower than during deposition of the pure metal alone. Results from the deposition of various elements are presented.; The aspects of the growth of alkaline earth oxides on silicon are explained. The transition from the silicon to the alkaline earth oxide as described through reflection high energy electron diffraction (RHEED) is presented and used to understand issues related to each stage of the growth. High quality, commensurate alkaline earth oxides are grown on silicon at room temperature and P _{O2 background} ∼ 3 × 10−8 Torr.; The growth of alkaline earth and rare earth oxide solid solutions and rare earth oxides (EuO) are described. The first reported epitaxial EuO on silicon is reported, enabled by the use of a thin buffer layer (13 Å) of SrO.; Using a strategy of transition from simple structures to the more complex, the growth of a perovskite (SrTiO₃) on silicon is demonstrated. Growth of a structurally optimized perovskite structure entails the transformation of a thin interfacial alkaline earth oxide layer into the initial perovskite cells. SrTiO₃ and La-doped SrTiO₃ on silicon are used to integrate a piezoelectric relevant for microelectromechanical systems (MEMS) applications and a ferroelectric relevant for a ferroelectric random access memory (FRAM) architecture. A d₃₃ value of over 400 pm/V under bias is measured for the piezoelectric (Pb(Mn_1/3Nb _2/3)O₃ -PbTiO₃) and a remanent polarization of 25 μC/cm2 and fatigue free behavior (>1012 cycles) for a low temperature (450°C) deposited ferroelectric (Pb(Zr,Ti)O ₃) is obtained.; Initial work concerning the growth of even more complex structures such as conducting and ferroelectric superlattices are described. Short period superlattices of LaTiO₃ and SrTiO₃ are successfully grown.