Abstract
High-quality single-crystal Y2O3 nano films have been grown epitaxially on Si (111) despite a lattice mismatch of 2.4 %. The films were electron beam evaporated from pure compacted powder Y2O3 target by molecular beam epitaxy (MBE). Structural and morphological studies were carried out by x-ray diffraction, reflectivity, and high-resolution transmission electron microscopy (HRTEM), with the initial epitaxial growth monitored by in-situ reflection high energy electron diffraction (RHEED). Chemical analysis were performed by in-situ X-ray photoelectron spectroscopy (XPS) and medium energy ion scattering (MEIS) accompanied with electrical measurement of I-V and C-V characteristics. The films have the cubic bixbyite phase with a remarkably uniform thickness and highly structural perfection. The films are well aligned with the Si substrate with an orientation relationship of Si (111)//Y2O3 (111), and a dominant in-plane expitaxy of Si [-110] || Y2O3 [-101] with domain size about 20 nm. Cross-sectional HRTEM micrographs confirm the observations using x-ray diffraction and reflectivity, namely the structural perfection and very sharp interface between the oxide and Si. From in-situ XPS results, an interfacial silicate layer was observed with an oxygen-deficient oxide layer on the top of the film. Even so, excellent leakage performance (JL~5.5×10-8A/cm2) is still observed. It is remarkable that a nano oxide grew excellently hetero-epitaxially on Si.