(Ba,Sr)TiO3 (BST) thin films with thicknesses ranging from 15 to 50 nm are prepared by a rf magnetron sputtering on Pt/SiO2/Si substrates. The dielectric constants of BST thin films increase with increasing deposition temperature and thicknesses. The leakage current increases with increasing deposition temperature and this prevents the deposition temperature of the 20 nm thick BST thin film from being increased to a value more than 640 °C. The leakage current is also critically dependent upon the postannealing temperature and atmosphere after the top electrode fabrication. The dielectric constant increases with increasing postannealing temperature which further reduces the SiO2 equivalent thicknesses of the BST thin films. A 20 nm thick BST thin film deposited at 640 °C and postannealed at 750 °C under N2 atmosphere for 30 min, shows a SiO2 equivalent thickness of 0.24 nm, dielectric dissipation factor less than 1%, and leakage current of about 40 nA/cm2 at ∓1.5 V.

The electrical conduction behaviors of sol-gel derived Pb(Zr, Ti)O3 (PZT) thin films on Pt electrodes were analyzed based on a fully depleted film, thermionic field emission, and space charge limited conduction model in the low and high electric field regions, respectively. For films having thicknesses ranging from 150 to 250 nm, no thickness-dependent variation in the dielectric constant was observed due to the relatively large thicknesses. The rather small film-thickness-dependent leakage current characteristics in the low-field region elucidates that the positive space charge density in the film is about 1018 cm−3, which is a smaller value than that of the sputter deposited (Ba, Sr)TiO3 thin films by an order of magnitude. The calculated interfacial potential barrier height and effective mass of electrons were 0.93 eV and 0.09m0, respectively. The slope larger than 2 from the log J vs log V plot in the high-field region implies that the energy level of electron traps are continuously distributed in the energy band gap.

SrTiO3 thin films are deposited on Pt/SiO2/Si substrates using RF magnetron sputtering in a temperature range from 200° C to 600° C. The film deposited at 600° C shows the best dielectric property and leakage current characteristics due to its good crystallinity and stoichiometric composition. Dielectric constant of the film deposited at 600° C decreases with decreasing thickness from 235 at 120 nm to 145 at 30 nm. Leakage current shows a constant value of about 30 nA/cm2 at 1.6 V in a thickness range from 50 nm to 120 nm but increases rapidly to 5 µ A/cm2 at 30 nm. The electrical properties of the films are explained by a model of the Pt/SrTiO3/Pt capacitor based on the band structure.

We propose a three-parametric extension of integrable non-uniform spin lattices in 1D. In our model, the spins are located at the equilibrium positions of particles interacting via the potential (sinh(r)) −2 , the particles being confined by some external field. The Lax representation, conserved current and special set of eigenvectors are presented in explicit form.

Pt/(Ba, Sr)TiO3/Pt capacitors are fabricated using DC and RF magnetron sputtering processes on thermally oxidized silicon wafers for ultralarge scale integrated dynamic random access memory (ULSI DRAM) applications. (Ba,Sr)TiO3 (BST) thin film deposited at 640°C to 20 nm thickness shows an equivalent SiO2 thickness (t oxeq) of 0.35 nm and a leakage current density, measured at an applied voltage of 1.5 V, of about 100 nA/cm2. t oxeq of the BST film and leakage current density are further decreased to 0.24 nm and 40 nA/cm2, respectively, by postannealing at 750°C after fabrication of the top electrode.