Structural and dielectric properties of spin-on barium-strontium titanate thin films

Abstract

Barium-strontium-titanate (Ba0.5Sr0.5)TiO3 thin film capacitors fabricated by a spin-on technique were studied. At room temperature the films have high dielectric constant ε, ranging from 22 to 151 at 1 MHz. Complex impedance spectroscopy was used in order to measure the frequency dependence of their dielectric properties. Cole–Cole reactance versus resistance of experimental data in the frequency range 10 Hz–10 MHz show semicircular behavior indicative of current leakage. The current leakage is proportional to the dielectric constant and in particular the lowest leakage current we measured at 1 MHz was 3×10−5 A/cm2 on samples with ε=22.

FE analysis of a low-frequency microstrip antenna

“…Fig. 2 shows the frequency dependence of the real part of the dielectric permittivity of a BST sample in comparison with measured data [7], having assumed , , and s. In ferrimagnetic media, the magnetic permeability tensor has, in general, the following Hermitian form:…”

“…In the following analysis, it is assumed that temperature is constant and that the nonlinearity due to the electric field may be neglected in consideration of the reduced values that are applied to feed the antenna. Measurements conducted on barium-strontium-titanate (BST) thin films have put in evidence that the frequency-dependence of such dielectric materials can be modeled by means of a simple-pole Debye model [7], [8] ( 2) where , , and are, respectively, the relative permittivity at infinite and zero frequency and the relaxation time. Fig.…”

“…In fact, relative permeability and permittivity appear in the approximate expressions of the resonant frequencies of such devices, and thus, ferrimagnetic and ferroelectric materials may be considered as antenna substrates since relative values in the order of 10 have been obtained for both [5]- [7]. Moreover, the use of ferrites is attractive because of the possibility to vary their magnetic permeability by means of a dc bias.…”

“…2. Measured[7] relative permittivity of a BST sample and its analytical fitting by means of a Debye model.…”

The preparation and formation mechanism of barium strontium titanate/silicon nanoporous pillar array composite film by sol-gel method

“…Recently, because of its unique combination of high dielectric constant, low dielectric loss, low leakage current density and good thermal stability [1,2], ferroelectric barium strontium titanate (BST) thin films had attracted a lot of attention for their promising potential application such as in dynamic random access memory [3,4], infrared detectors [5], sensors [6,7]and tunable microwave devices [3,8,9]. In order to be compatible with-standard silicon-based ultra-large-scale integration (ULSI) technology, it should be better to fabricate devices on silicon wafers.…”