Dependence of electrical properties on film thickness in lanthanum-doped lead zirconate titanate stannate antiferroelectric thin films

Abstract

Lanthanum-doped lead zirconate titanate stannate antiferroelectric thin films with compositions in antiferroelectric orthorhombic region have been prepared on Pt-buffered Si substrates by the sol–gel method, with the film thickness from 0.1 to 1.0 μm. The dependence of dielectric and ferroelectric properties on film thickness have been studied, with the emphasis on field-induced phase switching. The dielectric constant and maximum polarization decrease with the reduction of film thickness, which are similar to ferroelectric thin films. However, the decrease of film thickness also leads to the decrease of the phase switching fields, the appearance of remanent polarization in the hysteresis loops, and the smearing of antiferroelectric–ferroelectric phase switching. These phenomena are believed to be caused mainly by the stress effect between the film and substrate. Due to thermal mismatch, the films are under high tensile stress after annealing, and the stress effect becomes more significant with the decrease of film thickness. This makes the thinner films more preferable to the ferroelectric phase and causes the retention of ferroelectric phase in the films with thickness less than 0.4 μm.

( Pb , La ) ( Zr , Sn , Ti ) O 3 antiferroelectric thin films grown on LaNiO3-buffered and Pt-buffered silicon substrates by sol-gel processing

“…Apparently, the LNO layer with (100) orientation served as a template to enable the grain-on-grain local epitaxial growth of the PLZST films. Contrary to our findings described above, a (111)-preferred orientation of the PLZST films on the Pt-buffered substrates was reported in the work by Xu et al 10 This discrepancy might be due to the different fabrication processing, especially the heat treatment conditions. Their films were pyrolyzed at 600°C for 0.1 h after the deposition of each layer and annealed at 700°C for 1 h after the final layer deposition.…”

“…Several factors could contribute to thickness effects, and for different cases the dominant factor might be different. It was reported by Xu et al 10 that the phase switching fields increased with increasing film thickness in the range of 100 to 1000 nm. Their explanation was that the effect of the tensile stress in the film, which was originated from the thermal mismatch between the film and the substrate, tended to facilitate the antiferroelectric-to-ferroelectric phase switching (also known as phase transition).…”

“…However, the PLZST film with similar thickness ͑400 nm͒ but different preferred (111) orientation grown on the Pt-buffered silicon substrate by Xu et al gave an even larger saturation polarization (about 27 C/cm 2 with the testing frequency 50 Hz). 10 It is known that the (AFE) phase of PLZST has an orthorhombic structure with the antipolar directions along the pseudocubic ͗110͘, while the FE phase has a rhombohedral structure with the polar directions along the pseudocubic ͗111͘. 11,12 Therefore it is expected that the PLZST film with the preferred (111) orientation would show a larger polarization than films with non-(111) preferred orientation.…”

Polarization fatigue in antiferroelectric (Pb,La)(Zr,Ti)O3 thin films: The role of the effective strength of driving waveform

“…Based on this phase transition, AFE materials especially in the film form can find applications in various electronic devices including high-energy storage capacitors [1][2][3], high-strain micro-actuators and transducers [4,5], electrocaloric refrigeration [6], and so on. However, practical materialization of AFEs involves being exposed to several obstacles.…”

Low-temperature growth of (110)-preferred Pb0.97La0.02(Zr0.88Sn0.10Ti0.02)O3 antiferroelectric thin films on LaNiO3/Si substrate

“…In recent years PbZrO 3 -PbTiO 3 -based ferroelectric (FE) and antiferroelectric (AFE) thin films, such as Pb(Zr,Ti)O 3 (PZT) [1], (Pb,La)(Zr,Sn,Ti)O 3 (PLZST) [2] and Pb (Nb,Zr,Sn,Ti) O 3 (PNZST) [3], have been vastly investigated for possible applications in microelectromechanical system (MEMS). The sol-gel method has been most commonly used to fabricate PbZrO 3 -PbTiO 3 -based thin films on platinum electrodes because of its simple process, lower price, accurate chemical control and larger area production, and other advantages.…”