Growth and application of epitaxial heterostructures with polymorphous rare-earth oxides

• Published in: Journal of crystal growth 2013-09, Vol.378, p.177-179
• Main Authors: Dargis, R., Clark, A., Arkun, E., Roucka, R., Smith, R., Demkov, A.A., Lebby, M.
• Format: Article
• Language: English
• Subjects: A. Semiconductor on insulator epitaxy; A1. Crystal structure; A2. Single crystal growth; A3. Molecular beam epitaxy; B. Rare-earth oxides; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron states; Exact sciences and technology; Gallium arsenide; Germanium; Lanthanum oxides; Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Methods of electronic structure calculations; Molecular structure; Molecular, atomic, ion, and chemical beam epitaxy; Oxides; Physics; Rare earth compounds; Semiconductors; Silicon germanides; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2012.12.064

Cubic lanthanide sesquioxides consisting of cations with an atom radius larger that promethium could be used as a buffer layer for growth of semiconductors with a cubic structure (Ge, GaAs or SiGe) on Si due to the close matching of a lattice constant between the oxides and the semiconductors. However, the oxides have a stable hexagonal structure at temperatures higher than 600°C, which is typical for the epitaxy process. According to our ab initio density functional theory calculations, energy of molecular unit of hexagonal lanthanum oxide is lower than that of the cubic structure by 127meV. In this paper, we demonstrate epitaxial stabilization of pseudomorphic cubic structure of lanthanum oxide grown on a cubic template. The oxide layer can serve as a buffer for growth of Ge or GaAs layers on Si substrate. On the other hand, gadolinium oxide, which according to many studies has a stable cubic structure, was grown on hexagonal GaN. The single crystal monoclinic Gd2O3 could be used as a gate dielectric layer for GaN based electronic devices. ► Pseudomorphic rare-earth metal oxides are grown on cubic and hexagonal substrates. ► Lanthanum oxide adopts cubic structure from a cubic template layer if grown under optimized conditions. ► Monoclinic gadolinium oxide grows on hexagonal template.