Metal–oxide bilayer Raman scattering in SrTiO3 thin films

Abstract

We have used a metal-oxide bilayer Raman scattering technique to study lattice dynamics in SrTiO 3 thin films. The SrTiO 3 thin films were epitaxially grown on a conducting metal-oxide layer which reflects the exciting laser beam so that it does not enter the LaAlO 3 substrate. Raman scattering from the SrTiO 3 thin films was clearly observed, including the first-order Raman peaks forbidden by the cubic symmetry in single crystals. We suggest that strain exists in the films, which changes the crystal symmetry and will affect the dielectric properties of the SrTiO 3 thin films.

Electric-Field-Induced Soft-Mode Hardening inSrTiO3Films

“…The soft modes have also been seen in the case of uniaxial stress-induced [11] and hydrostatic pressure-induced [12] ferroelectricity and using far-IR spectroscopy [13], neutron scattering [14], and hyper-Raman scattering [15]. In our previous studies of STO thin films grown on LaAlO 3 substrates we observed first order Raman scattering by hard-mode TO 2 and TO 4 phonons, while the soft TO 1 mode has not been detected [16,17]. In this paper, we describe Raman scattering experiments in STO thin films grown on STO substrates with a SrRuO 3 (SRO) buffer layer in which application of an electric field allowed detailed investigation of the soft modes.…”

Temperature‐dependent structural characterization of sol–gel deposited strontium titanate (SrTiO3) thin films using Raman spectroscopy

“…Currently, potential candidates such as Ba 1 x Sr x TiO 3 (BST) for room temperature and SrTiO 3 (STO) for cryogenic temperatures are preferred because of their high dielectric constants (ε r ), good thermal stability and high frequency characteristics or nonlinear polarizability and hence should be favored for dielectric tuning as reported by Devonshire almost half a century ago. 4 The properties of almost all materials in general and ferroelectrics in particular in thin-film form differ from those of their bulk counterparts. 5 STO thin films have therefore been widely studied.…”

Characterization of aerosols from RDD surrogate compounds produced by fast thermal transients

“…Finally, Raman spectroscopy permitted to observe differences be- tween the pellet and the collected aerosols (as shown in Figure 8): the former showed the typical broad bands of the SrTiO 3 crystal (as reported in [26] at ca. 200-500 and 600-750 cm −1 ), while the latter showed bands related to first-order vibrations (broad bands at ca.…”