TITLE:
Thickness Dependence of Dielectric Characteristics of SrTiO3 Thin Films on MgAl2O4 Substrates
AUTHORS:
Ryuhei Kinjo, Iwao Kawayama, Hironaru Murakami, Masayoshi Tonouchi
KEYWORDS:
Strontium Titanate; Ferroelectric; Soft Mode; Thin Film; Strain Effect
JOURNAL NAME:
Advances in Materials Physics and Chemistry,
Vol.3 No.1,
March
28,
2013
ABSTRACT: SrTiO3 (STO) thin films of different
thicknesses were deposited on MgAl2O4 (MAO) substrates to
investigate the in-plane strain effect on the soft-mode frequency of the STO
films. X-ray reciprocal space mapping (X-RSM) results indicate that there was
no relaxation of the in-plane lattice strain of the STO films on MAO. Shifts in
the soft-mode frequencies with a decrease in the film thickness were observed
using terahertz time-domain spectroscopy (THz-TDS). However, despite the larger
lattice mismatch between STO and MAO than that between STO and DyScO3 (DSO), the shifts in the soft-mode frequencies of the STO films on MAO were
smaller than those on DSO. The results indicate that the soft-mode frequencies
of the STO films on MAO are affected by the c-axis
(out-of-plane) lengths.