Influence of oxygen atmosphere on crystallization and properties of LiNbO3 thin films

Simões, Alexandre Zirpoli; Zaghete, M. A.; Stojanovic, B. D.; González, Alejandra Hortência Miranda; Riccardi, C. S.; Cantoni, Marco; Varela, José Arana

doi:10.1016/s0955-2219(03)00453-9

Cited by 49 publications

(14 citation statements)

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“…In PTD process, we used a mixture of polyol precursor solution of metal chlorides (i.e., 0.2 M of barium chloride (BaCl 2 Á2H 2 O, Showa, 99%) and 0.2 M of titanium tetrachloride (TiCl 4 , Aldrich, 99.9%) with sparingly soluble metal salts in water) with deionized water and ethylene glycol as a solvent under ambient conditions without the need for refluxing to grow the BaTiO 3 film. The preparation of polyol precursor solution is similar to the polyol process [15,16], using diol or polyalcohol (for example, ethylene glycol or glycerol) as a solvent to reduce metal salts to metal particles, and the Pechini process [17,18], except that citric acid or other chelating agents are not utilized. The polyol precursor solution also ensures a homogeneous metal distribution and prevents unwanted reaction that can lead to the formation of undesired phases.…”

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confidence: 99%

Ultrathin barium titanate films by polyol thermal decomposition process

2010

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We have successfully fabricated barium titanate (BaTiO 3 ) films on Si (100) and Pt(111)/Ti/SiO 2 /Si substrates using the polyol thermal decomposition (PTD) process by spin-coating technique. In PTD process, we confirmed that the crystalline oxycarbonate Ba 2 Ti 2 O 5 CO 3 films were directly formed as a consequence of evaporation of polyol precursor solution prepared simply by mixing metal chlorides and ethylene glycol, and then converting them into crystalline BaTiO 3 films through thermal decomposition at [500°C. This feature makes it possible to grow densely packed and crack-free BaTiO 3 films as thin as 70 Å per cycle. Although PTD is described here for a complex metal-oxide film of BaTiO 3 , other simple and complex metal-oxide thin films with high-dielectric constant materials are also likely to be suitable for deposition with accurate control of film thickness and composition using the polyol precursor solutions.Metal-oxide thin films, such as AO and ABO 3 , are important components in a wide array of electronic and optical devices, and their study and manufacture involve major aspects of current science and technology [1]. The ability to deposit and tailor reliable metal-oxide films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. Many different methods are used to make these thin films, such as various physical and chemical vapor depositions mainly dependent on vacuum deposition techniques, and many new techniques have been developed [1][2][3]. However, the use of these vacuum deposition techniques, the high cost of necessary equipment, and restriction of coatings on a relatively small area have limited their potential applications [4]. On the other hand, chemical solution depositions (CSD) such as sol-gel and metallo-organic decomposition (MOD) are more cost-effective, but many metal oxides cannot be deposited, and the control of stoichiometry is not always possible owing to differences in chemical reactivity among the metals [5]. In particular, precise control of film thickness, crystallinity, and morphology are significant problems to be overcome in CSD [6].One of the challenges in solution-based processes of complex metal-oxide films has been to produce high-quality films with desired chemical composition. The sol-gel method among the CSD processes is one of the most important approaches, which are being extensively used for the fabrication of complex oxide thin films. The sol-gel method show attractive advantages due to the fact that films with extremely uniform composition over large areas can be obtained from chemical solution deposition [7]. A key issue of any CSD thin films processing is the chemistry of precursor solution, which governs the properties of the final oxide layer. Even more challenging for sol-gel processing of complex metal-oxides is the identification of a solvent system in which the multiple organometallic precursors are reciprocally compatible. Recently, a few attempts have been reportedly made to ad...

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confidence: 99%

Ultrathin barium titanate films by polyol thermal decomposition process

2010

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“…It is seen from Table 1 that the thermal annealing leads to a decrease in the relaxation time of the "slow" relaxation process, which seems to be conditioned by the influence of the grain boundaries in the LiNbO 3 film. As it has been proposed [12] , vacancies appearing inevitably in the LiNbO 3 film during the growing process play a crucial role in the relaxation process. For example, the oxygen vacancies (positive charges) may have originated from the sputtering process of the film and can be associated with bulk properties of the film.…”

Section: Impedance Spectroscopymentioning

confidence: 91%

“…It is important to emphasize that relaxation phenomena underlie many electrical properties of the ferroelectric film and can even block switching process, which is the stumbling block of the contemporary electronics. From this point of view, various approaches, such as optimization of the sputtering parameters [12] , doping [13] and annealing [14] have been applied to obtain the desired result in switching of the ferroelectric devices. Consequently, there is no doubt that investigation of the relation between the structure of the grown films and their relaxation properties is urgent.…”

Section: Introductionmentioning

confidence: 99%

Electrical properties and local domain structure of LiNbO3 thin film grown by ion beam sputtering method

Иевлев

Shur²,

Sumets

et al. 2013

ACTA METALL SIN

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The nanocrystalline ferroelectric LiNbO 3 films on (001) Si substrates with the random orientation of polycrystalline grains and the predominance of the grains with lateral orientation of the polar axis were grown using the ion beam sputtering method. The remanent polarization and the coercive field are 12 μC/cm 2 and 29 kV/cm, respectively. The thermal annealing leads to the coarsening of the grains. The appearance of the "local texture," which gives rise to the unipolarity of the heterostructures caused by the predominance of the one direction in the vertical component of the spontaneous polarization, is investigated.

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“…Furthermore, while bulk crystals generally require reducing atmospheres [52] or vacuum [53] for significant oxygen to diffuse out of the crystal matrix during annealing, we found that in small crystallites the out diffusion occurs even when annealed in an ambient atmosphere, resulting in black powders. To prevent the loss of oxygen from the material, we annealed the powders under a continuous flow of oxygen (ultra-high purity grade), a method that has been shown to inhibit the reduction process for bulk crystals [53], although for thin films there have been some indications that excess oxygen may potentially be absorbed and produce defects [54]. To inhibit the out-diffusion of lithium, we employed the well-known technique used for LiNbO 3 wafer processing of introducing small amounts of water vapor into the oxygen by bubbling the gas through a column of deionized water [55,56].…”

Section: Sample Preparationmentioning

confidence: 99%

Effects of mechanical processing and annealing on optical coherence properties ofEr3+:LiNbO3 powders

Lutz

Veissier

Thiel

et al. 2017

Journal of Luminescence

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Optical coherence lifetimes and decoherence processes in erbium-doped lithium niobate (Er 3+ :LiNbO3) crystalline powders are investigated for materials that underwent different mechanical and thermal treatments. Several complimentary methods are used to assess the coherence lifetimes for these highly scattering media. Direct intensity or heterodyne detection of two-pulse photon echo techniques was employed for samples with longer coherence lifetimes and larger signal strengths, while time-delayed optical free induction decays were found to work well for shorter coherence lifetimes and weaker signal strengths. Spectral hole burning techniques were also used to characterize samples with very rapid dephasing processes. The results on powders are compared to the properties of a bulk crystal, with observed differences explained by the random orientation of the particles in the powders combined with new decoherence mechanisms introduced by the powder fabrication. Modeling of the coherence decay shows that paramagnetic materials such as Er 3+ :LiNbO3 that have highly anisotropic interactions with an applied magnetic field can still exhibit long coherence lifetimes and relatively simple decay shapes even for a powder of randomly oriented particles. We find that coherence properties degrade rapidly from mechanical treatment when grinding powders from bulk samples, leading to the appearance of amorphous-like behavior and a broadening of up to three orders of magnitude for the homogeneous linewidth even when low-energy grinding methods are employed. Annealing at high temperatures can improve the properties in some samples, with homogeneous linewidths reduced to less than 10 kHz, approaching the bulk crystal linewidth of 3 kHz under the same experimental conditions.

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Influence of oxygen atmosphere on crystallization and properties of LiNbO3 thin films

Cited by 49 publications

References 14 publications

Ultrathin barium titanate films by polyol thermal decomposition process

Ultrathin barium titanate films by polyol thermal decomposition process

Electrical properties and local domain structure of LiNbO3 thin film grown by ion beam sputtering method

Effects of mechanical processing and annealing on optical coherence properties ofEr3+:LiNbO3 powders

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