Effects of substrate on the dielectric and tunable properties of epitaxial SrTiO3 thin films

Abstract

Tunable dielectric thin films of SrTiO 3 ͑STO͒ were prepared on different single-crystalline substrates, including insulating LaAlO 3 , conductive Nb-doped STO ͑NSTO͒, and superconducting YBa 2 Cu 3 O 7−␦ . Substrate effects including morphology, orientation, and lattice mismatch induced strains were investigated. We found that a change of substrate used for STO thin films can strongly affect the dielectric properties of STO thin films in terms of dielectric constant, loss tangent, and tunability. Effects of substrate properties on the temperature dependence of dielectric constant and loss tangent were investigated. At low temperatures, STO thin films under minimal strain yield high dielectric constant and low loss tangent while the thin films under either tensile or compressive strain exhibit the reduced dielectric constant and high loss. The tunability of about 77% in STO/ NSTO system, close to the value found in STO single crystal, was observed at 10 K. Physical origin of observed phenomena was discussed.

Uncovering Two Competing Switching Mechanisms for Epitaxial and Ultrathin Strontium Titanate-Based Resistive Switching Bits

“…capacitances measured in 5 nm devices as they are also shown in literature to strongly affect the relative permittivity [51][52][53][54]. While for 50 nm devices the capacitance and permittivity are already close to the expected values for bulk SrTiO 3 .…”

Near-room-temperature control of magnetization in field effect devices based on La0.67Sr0.33MnO3 thin films

“…According to the Thomas-Fermi theory, the induced volume charge density in LSMO decays exponentially moving away from the surface like 0 exp͑−z / LSMO ͒, where z is the distance from the surface and 0 = / LSMO is the "surface" modification of the charge density. Assuming STO = 200, as obtained from the measurement of the time discharge of the capacitance associated with the FED and in agreement with data reported in literature, [22][23][24][25] we find 0 = 2.45ϫ 10 2 C / cm 3 when 2.5 V are applied. Electrons are then injected in LSMO with a concentration being 1.5ϫ 10 21 cm −3 at the interface with STO and ϳ2 ϫ 10 20 cm −3 one unit cell away from the interface, where the second plane of Mn atoms is placed if we suppose a MnO 2 termination of the LSMO film.…”

Tuning of near-infrared luminescence of SrTiO3:Ni2+ thin films grown on piezoelectric PMN-PT via strain engineering

“…On the other hand, the host of SrTiO 3 (STO) here is known as an incipient ferroelectric and foundational material of oxide-based heterostructures 16 . STO thin films with tunable dielectric properties associated with structural phase transition under strain have been systematically studied 17 18 . Our recent work indicates that STO is also a suitable NIR phosphor matrix for Ni 2+ ions 19 .…”