Articles you may be interested inFormation of nickel silicide and germanosilicide layers on Si(001), relaxed Si Ge ∕ Si ( 001 ) , and strained Si/relaxed Si Ge ∕ Si ( 001 ) and effect of postthermal annealingThe formation of NiSi films on Si was studied using Rutherford backscattering spectrometry, atomic force microscopy, and ellipsometry. NiSi is an attractive candidate for use as a gate contact material due to its low metal-like resistivity and large processing window ͑350-750°C͒. Three phases, Ni 2 Si, NiSi, and NiSi 2 , were identified in this temperature range, and their optical databases in the 2-4 eV photon range were established, and used to model real-time ellipsometry data. It is shown that real-time ellipsometry can be used to monitor and follow the formation of the various Ni-Si phases. We have also observed the onset of agglomeration of the silicide for longer time anneals at temperatures of 500-700°C, which is much lower than 1000°C where agglomeration has been reported to occur.

The modified transverse Ising model considering double-peak probability distribution functions is constructed and applied to investigate the thermodynamic properties of compositionally graded Ba1−xSrxTiO3 thin films. Spatial nonuniformity in compositional concentration is exhibited to give rise to nonuniformity in polarization with corresponding spatial variation. It is found that the magnitude and the sign of the polarization gradients are dependent on the compositional gradient. We also find that the origin of polarization offset is strongly related to not only the compositional gradient but also the temperature. In addition, the compositional gradient plays an important role in the pyroelectric coefficient of the graded film versus temperature, where one or two broad and smooth pyroelectric peaks occur except for a sharp peak at the Curie temperature.

Articles you may be interested inEffect of Pt bottom electrode texture selection on the tetragonality and physical properties of Ba0.8Sr0.2TiO3 thin films produced by pulsed laser deposition J. Appl. Phys. 112, 044105 (2012); 10.1063/1.4748288Bulk-like dielectric properties from metallo-organic solution-deposited SrTiO3 films on Pt-coated Si substrates

No abstract

This investigation reports on the phase transition and dielectric properties of compositionally graded Ba 1-x Sr x TiO 3 (BST) thin films with x decreasing from 0.20 to 0.10 in successive slabs, based on the transverse-field Ising model (TIM) within the framework of mean field theory. The random bond model of related parameters is applied to mimic doping. The effect on polarization and dielectric susceptibility arising from a gradient in composition is taken into account. The peaks of dielectric susceptibility versus temperature become comparatively flat by modulating appropriate thickness in each slab in compositionally graded BST thin films, which means that the thickness may weaken the effect of composition gradient. When increasing the number of slabs of thin films, the dielectric susceptibility shows good temperature stability in a wide temperature range, which is useful for reducing the temperature coefficient of dielectric susceptibility without depressors.

No abstract

(Ba0.6Sr0.4)TiO3 (BST) thin films were deposited at a low temperature of 420 °C using thin SrTiO3 (STO) buffer layers on (1 0 0)LaNiO3/Si substrates by radio frequency magnetron sputtering. BST thin films showed a pure perovskite phase and preferred (h 0 0) orientation. The effect of the SrTiO3 layer thickness on crystallinity, dielectric and electrical properties of BST thin films was investigated. Compared with single BST films, the BST/STO multilayer thin films exhibited improved crystallinity when the STO layers were thicker than 10 nm. The dielectric constant clearly increased and the dielectric loss decreased with a 10 nm thick STO buffer layer. As a result, the figure of merit of films at a certain frequency reached the maximal value of 19.7 with the applied voltage of 6 V. In addition, the multilayer films exhibited a reduced leakage current density, which could be attributed to the improved crystallinity of the BST films by using the thin STO buffer layer.

( Ba 0.5 ,Sr 0.5 )TiO 3 (BST) thin films were deposited on MgO, Si, SiO2 and Ir surfaces by ion beam sputter deposition in oxygen at 700 °C. In situ spectroscopic ellipsometry (SE) has been used to investigate the evolution of the BST films on different surfaces during both deposition and postannealing processes. First, the optical constants of the BST films in the photon energy range of 1.5–4.5 eV were determined by SE analysis on crystallized BST films deposited on MgO single crystal substrates. The interfaces in BST/Si and BST/SiO2/Si structure were examined by SE and Auger electron spectroscopy depth profiles. Subcutaneous oxidation in the BST/Ir structure was observed by in situ SE during both ion beam sputter deposition and postdeposition annealing in oxygen at 700 °C. A study of the thermal stability of the Ir/TiN/SiO2/Si structure in oxygen at 700 °C was carried out using in situ SE. The oxidation of Ir was confirmed by x-ray diffraction. The surface composition and morphology evolution after oxidation were investigated by time of flight mass spectroscopy of recoiled ions (TOF-MSRI) and atomic force microscopy. It has been found that Ti from the underlying TiN barrier layer diffused through the Ir layer onto the surface and thereupon became oxidized. It was also shown that the surface roughness increases with increasing oxidation time. The implications of the instability of Ir/TiN/SiO2/Si structure on the performance of capacitor devices based on this substrate are discussed. It has been shown that a combination of in situ SE and TOF-MSRI provides a powerful methodology for in situ monitoring of complex oxide film growth and postannealing processes.