Synthesis of PbTiO₃Thin Films by Annealing Multilayer Oxide Structures in Vacuum

Abstract

This article presents investigation of syntheses of perovskite PbTiO3 thin films by using reactive magnetron layer-by-layer deposition on Si (100) substrate and post-annealing in air and vacuum (p = 5 × 10 −3 Pa). The film stoichiometry was accurately controlled by the deposition of individual layers with the required (≈ 1 nm) thickness, using the substrate periodic moving over targets. Deposited thin films were annealed in air and in vacuum at 670• C and 770• C for 1 h, respectively. The morphological, structural, and chemical properties of thin films deposited at 300• C substrate temperature and post-annealed thin films using either conventional annealing and thermal annealing in vacuum at different temperatures were investigated and compared between. X-ray diffraction measurements of thin films annealed in air show formed crystalline perovskite PbTiO3 phase with tetragonality c/a = 1.047. The crystallite size of oxidized films depends on the substrate temperature. The structure of post annealed in vacuum thin films strongly depends on Pb/Ti atomic ratio. It was observed that the best structure and morphology forms when atomic ratio of Pb/Ti was 0.80. Pseudocubic phase of lead titanate forms with sufficiently low tetragonality at 670• C temperature.

Influence of the Annealing Environment on the Structure and Ferroelectric Properties of Lead Titanate Thin Films

“…The crystallite size was determined as 26 nm. Our previous investigations [21] indicated that the c/a ratio was 1.047, and the average crystallite size was 65 nm when the PbTiO 3 films were annealed at 770 • C in air. Different results were obtained after annealing as-deposited film in an oxygen environment at 1.33 Pa pressure (Figure 2b).…”

“…O. Azaroual et al [29] found that the PbTiO 3 films deposited using the sol-gel technique and annealed at 650 • C showed a remnant polarization of 18 µC/cm 2 and coercive field of 121 kV/cm. Our previous studies [20][21][22] demonstrated that the phase structure, surface morphology and ferroelectric properties of the PbTiO 3 films strongly depended on the substrate temperature or postdeposition annealing conditions. It was observed that the c/a ratio and crystallite size of the PbTiO 3 films annealed at 770 o C depend on the Pb/Ti ratio [21].…”

“…Our previous studies [20][21][22] demonstrated that the phase structure, surface morphology and ferroelectric properties of the PbTiO 3 films strongly depended on the substrate temperature or postdeposition annealing conditions. It was observed that the c/a ratio and crystallite size of the PbTiO 3 films annealed at 770 o C depend on the Pb/Ti ratio [21]. The PbTiO 3 films formed in situ on the hot substrates (temperature varied from 450 to 550 • C) showed a remnant polarization of 60 µC/cm 2 and coercive field of 150 kV/cm [20].…”

“…However, the use equipment is expensive, and to obtain the desirable film composition, an adapted target composition is required [15,16]. Magnetron sputtering is one of the most prospective methods for PbTiO 3 thin film formation because of its high deposition rate, the possibility of using commercially available large area deposition systems, the control of the substrate temperature during the deposition and the relatively low cost [12,15,17,[20][21][22][23][24]. R. Nishino et al [15] investigated thin PbTiO 3 films synthesized using pulsed laser deposition and discovered that the remnant polarization depended on the thickness of the PbTiO 3 films.…”

Self-Recovery of Defective PbTiO3 Film with Enhanced Piezoelectricity by Homogenizing Annealing

“…However, the obtained phase hysteresis loops are not symmetric in terms of coercive voltage and remanent polarization for all three films. A possible imprint effect may be responsible for these asymmetric behaviors: the presence of defects in the film, including impurities, oxygen vacancies, and surface/interface defects. − …”