Optical constants, band gap, and infrared-active phonons of (LaAlO3)0.3(Sr2AlTaO6)0.35 (LSAT) from spectroscopic ellipsometry
Abstract
Using spectroscopic ellipsometry, the authors determined the optical constants (complex dielectric function) for (LaAlO3)0.3(Sr2AlTaO6)0.35 (LSAT) from 0.01 to 6.5 eV. Above 0.5 eV, the data were described with a sum of two Tauc-Lorentz oscillators and two poles. A direct gap of 5.8 ± 0.1 eV was found. An Urbach tail extends to even lower photon energies and makes the crystal opaque above 4.8 eV. Using Fourier-transform infrared ellipsometry, the lattice dynamics was studied. Nine pairs of transverse/longitudinal phonons were found and attributed to disorder in the La/Sr sublattice, ordering in the Al/Ta sublattice, and two-phonon absorption.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Aug 04, 2016
- Source ID
- 10.1116/1.4960356
Entities
People
- Christian Bernhard
- Felicia S. Manciu
- Jacqueline Cooke
- Premysl Marsik
- Stefan Zollner
- T. Nathan Nunley
- Travis I. Willett-gies
Organizations
- Army Research Office
- Division of Materials Research
- New Mexico State University
- Swiss National Science Foundation
- University of Fribourg
- University of Texas at El Paso