Growth and Characterizations of Hydrogen-Bonded Organic Ferroelectric DC-MBI films using Vacuum Deposition.*

The molecular crystal of 5,6-Dichloro-2-methylbenzimidazole (DC-MBI) is ferroelectric (uniaxial c-axis polarization) owing to its ordered hydrogen bonds [1]. Utilizing hydrogen-bonded organic system [2] shows promise as an alternative to conventional inorganic ferroelectrics containing lead or rare elements [3]. However, achieving ferroelectricity in organic thin films is challenging due to morphological and crystalline complexities. In this study, we utilized the physical vapor deposition technique (~10^-07 Torr) to grow and optimize mm-thick films with good coverage. We observe several distinct morphological variations within a film grown at various substrate temperatures. Tailoring these morphologies is essential for improved crystallization, ultimately enhancing the ferroelectric nature of the film at ambient room temperature with stability even beyond room temperature.

 

[1] Horiuchi, S., Kagawa, F., Hatahara, K. et al., Nat Commun 3, 1308 (2012)

[2] Jiang, X. et al. Appl. Phys. Lett. 109, 102902 (2016)

[3] G. Shirane, E. Sawaguchi, and Y. Takagi, Phys. Rev. 84 (1951)