Effects of in-plane compressive stress on electrical properties of (Ba,Sr)TiO3 thin film capacitors prepared by on- and off-axis rf magnetron sputtering

Abstract

This study investigated the structural and electrical properties of (Ba,Sr)TiO3 (BST) thin film capacitors with thicknesses ranging from 18 to 215 nm, which were prepared by on- and off-axis rf magnetron sputtering technique on Pt/SiO2/Si substrates. The deposition rate and cation composition ratios of the films were controlled to be the same regardless of the sputtering geometry. All the films show elongations in the out-of-plane lattice spacing, suggesting the presence of compressive stress with a smaller value by on-axis sputtering than by the off-axis system. There was no thickness dependence of the strain in the polycrystalline BST films. The BST films deposited using the on-axis system showed a higher bulk dielectric constant with a higher interfacial capacitance and a lower leakage current level than the films produced by the off-axis system. The strain effect was proposed to explain the correlations between the structural and electrical properties.

Enhanced photovoltaic properties in polycrystalline BiFeO3 thin films with rhombohedral perovskite structure deposited on fluorine doped tin oxide substrates

“…Obviously, a narrow band gap is beneficial to enhance the photovoltaic effect of BFO. However, polycrystalline BFO films prepared by a conventional chemical solution deposition process (CSD) based on using 2-methoxyethanol and acetic acid as solvent mainly show pseudocubic structure [8,12] due to tensile stress [13] within the ferroelectric films. As we know, except the kinds of substrates, the kinds of solvents in the precursor solution also have high effect on the structure of the as-prepared films.…”

Modification of electronic structure in compressively strained vanadium dioxide films

“…Of particular note is a process referred to as "shot peening", in which compressive strain arises as a result of the sample being bombarded by energetic particles during growth. Compressive in-plane strain in sputtered oxide films is often attributed to this effect 28,29 . Thermal strain from the mismatch of the coefficient of thermal expansion between the film and substrate may also be present.…”

Calculation of the intrinsic dead layers thicknesses from Au/Ba0.5Sr0.5TiO3/Pt thin film capacitors

“…However, when thin BST films is being produced, a common problem involving the decrease of dielectric constant with respect to film thickness is still an unsolved problem [10]. At present, there are assumptions that such phenomenon is caused by the presence of an intrinsic dead layer [11], defects leading to electrode polarization [12], and film stress from the substrate [13]. Thus, accurately quantifying the characteristics such as the thickness dependence of the dielectric constant in the ferroelectric film and understanding its origin is an important task to be solved before practical applications.…”