Electric-field assisted nucleation processes of croconic acid films

Yuan, Yifan; Jiang, Xuanyuan; Poddar, Shashi; Xu, Xiaoshan

doi:10.1039/c9ce01493d

Cited by 13 publications

(13 citation statements)

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“…The maximum nucleation rate occurs at an intermediate temperature as a compromise between diffusion and supersaturation. 13 For MBI films, the nucleation density and coverage rate decreases rapidly from 216 to 226 K, while the nucleation density is similar between 226 and 236 K (Figure S7). Therefore, the deposition temperature 230 K in 10 −7 torr pressure for the MBI films in this study is in the high-temperature tail of the nucleation rate−temperature relation, which has the desirable small nucleation rate.…”

Section: ■ Discussionmentioning

confidence: 93%

“…Here, we grow MBI films using low-temperature physical vapor deposition (PVD) in a high vacuum followed by restrained crystallization. Despite the advantages of precise thickness control and minimal contamination, PVD has not been exploited for MBI film growth due to the poor sticking factor, which is related to the low melting temperature (176.5 °C in air) that makes the solid phase unstable in high vacuum (<10 –6 torr) at room temperature. Hence, the low temperature growth is necessary.…”

Section: Introductionmentioning

confidence: 99%

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Highly Oriented Organic Ferroelectric Films with Single-Crystal-Level Properties from Restrained Crystallization

Yuan

Jiang

et al. 2022

Crystal Growth & Design

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Device applications often require thin film growth with quasi-two-dimensional morphology and crystallization, which are not always compatible. In this work, we exploit the method of low-temperature deposition followed by restrained crystallization (LDRC) in the growth of crystalline organic molecular thin films, which tend to grow three-dimensionally with random orientations. We demonstrate that for 2-methylbenzimidazole, a molecular ferroelectric that tends to crystallize in spherulites, the quasi-twodimensional films can be grown using LDRC with highly oriented polar axes and single-crystal-level ferroelectric properties. The crystallization process was shown to occur during the postdeposition annealing process using the in situ electrical measurements. The limited diffusion, low nucleation density, and low activation energy were found to be critical for the formation of the plate-shaped quasi-two-dimensional films. These results mark an important step in elucidating the LDRC as an effective and general approach for fabricating films with balanced crystallinity and morphology which are critical for applications.

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Section: ■ Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Highly Oriented Organic Ferroelectric Films with Single-Crystal-Level Properties from Restrained Crystallization

Yuan

Jiang

et al. 2022

Crystal Growth & Design

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“…However, similar optimization attempts on thicker or thinner films have not been reported yet. Likewise, Yuan et al 126 studied the temperature dependence of the nucleation rate of CA films with and without electric field-assisted growth and observed that the maxima of the grain density shifts in temperature when an electric field is applied during growth. Similarly, the void defects arising at the interface between CA films and substrates such as Si and SiO 2 have been studied by Peterson et al 127 Furthermore, Hu et al 70 have been able to grow micrometer thick CA films with crystallites uniaxially oriented, c -axes perpendicular to the film plane, without using any in situ electric field and have demonstrated stable ferroelectric properties as well as a non-volatile memory switching behavior stabilized by space charges.…”

Section: Croconic Acidmentioning

confidence: 99%

Organic ferroelectric croconic acid: a concise survey from bulk single crystals to thin films

Mohapatra¹,

Cherifi‐Hertel²,

Kumar³

et al. 2022

J. Mater. Chem. C

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“…Likewise other organic materials, physical vapor deposition (PVD), and solution processes could be adopted for the preparation of MF films and devices. − However, polycrystalline films with poor ferroelectric properties are usually obtained from the PVD method. Solution processing could be an efficient way to obtain highly crystalline MF films.…”

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confidence: 99%

Single-Crystalline Thin-Film Memory Arrays of Molecular Ferroelectrics with Ultralow Operation Voltages

Chen

Zhou

et al. 2022

ACS Materials Lett.

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Though most of the recently developed molecular ferroelectrics (MFs) exhibit excellent ferroelectric properties, the practical applications are still impeded by the limited polarization axes, poor processing capability for a high-quality thin film, and the incompatibility with matured lithography techniques for microelectronics. Here, we successfully demonstrated MF-based single-crystalline microdevice arrays using a lithography-compatible, solution-processed strategy that can avoid the above-mentioned obstacles at one time, i.e., dewetting-assisted patterning crystallization strategy. As a protype, uniform and well-aligned single-crystalline thin-film arrays of multiaxial MF [3-oxoquinuclidinium]ClO4 ([3-O-Q]ClO4) are prepared. Owing to the well-aligned crystallographic orientation and polarization direction, the obtained single-crystalline nonvolatile memory (NVM) arrays can exhibit an ultralow operating voltage of ∼1.6 V and long endurance cycles of 106, which are superior to other organic NVM devices. This work implies a promising route to high-density single-crystalline memory arrays for data storage, especially for low-cost flexible electronics.

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Electric-field assisted nucleation processes of croconic acid films

Abstract: An external electric field can affect the growth dynamics of croconic acid (CA) films, especially the heterogeneous nucleation process, as evidenced by the shift of temperature dependence of the nucleation rate in the electric field.

Cited by 13 publications

References 24 publications

Highly Oriented Organic Ferroelectric Films with Single-Crystal-Level Properties from Restrained Crystallization

Highly Oriented Organic Ferroelectric Films with Single-Crystal-Level Properties from Restrained Crystallization

Organic ferroelectric croconic acid: a concise survey from bulk single crystals to thin films

Single-Crystalline Thin-Film Memory Arrays of Molecular Ferroelectrics with Ultralow Operation Voltages

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