Ferroelectric fatigue endurance of Bi4−xLaxTi3O12 thin films explained in terms of x-ray photoelectron spectroscopy

Abstract

The nature of defects in polycrystalline Bi 4−x La x Ti 3 O 12 ͑BLT͒ thin films with x = 0.00, 0.25, 0.50, and 0.75 was evaluated by x-ray photoemission spectroscopy measurements. The influence of oxygen vacancies and substitution of Bi for La atoms were discussed. In the BLT thin films, it was found that the oxygen ions at the metal-oxygen octahedral were much more stable than those at the ͓Bi 2 O 2 ͔ layers. On the other hand, for Bi 4 Ti 3 O 12 ͑BIT͒ thin film, oxygen vacancies could be induced both at the titanium-oxygen octahedral and at the ͓Bi 2 O 2 ͔ layers. The oxygen-vacancy defect pairs determined in BIT and Bi 3.75 La 0.25 Ti 3 O 12 ͑BLT025͒ can pin the polarization of surrounding lattices leading to fatigue of capacitors. Meanwhile, the concentration of similar defect pairs is relatively low in heavily doped BIT films and then good fatigue resistance is observed.

Leakage current mechanism and effect of oxygen vacancy on the leakage current of Bi5Nb3O15 films

“…The oxygen vacancies were also expected to exist in the Bi 4−x La x TiO 3 films and they were used to explain the fatigue property of the films. 8,9 In addition, all the films had a very smooth surface and the variation of the surface roughness with OPPs was negligible, ranging between 0.21 and 0.14 nm, as shown in the inset of Fig. 2(a).…”

Structural and relaxor behavior of (Ba1−xLax)(Ti0.85Sn0.15)O3 ceramics obtained by solid state reaction

“…Smyth [37] explained their results on the dependence of conductivity of SrTiO 3 on partial pressure of oxygen on the basis of presence of unavoidable excess acceptor impurities in the starting raw materials. These impurities are acceptor in nature and are in relatively more natural abundance as compared to donors [38,39]. These acceptors (assuming a valency difference of one between Ba site ion and the substituent, M) lead to the generation of oxygen vacancies as follows:…”

Piezoresponse behavior of niobium doped bismuth ferrite thin films grown by chemical method

“…Recently, Higuchi et al [10] have studied the synthesis and ferroelectric properties of BiFeO 3 thin films grown by sputtering, while Li et al [11] have employed a cosputtering method to obtain BiFeO 3 thin films on Pt/Ti/SiO 2 /Si substrates. Our group has expanded significant effort in develop synthetic routes of thin films [12,13] and we have previously reported the preparation of bismuth-based thin films grown on Pt (1 1 1)/Ti/SiO 2 /Si substrates with good structural, microstructural and electrical properties by the soft chemical method [14][15][16][17]. In order to improve physical properties of multifunctional materials, it has been noticed that a portion of the constituent element should be substituted by alternative atoms.…”