Enhancement of electro-optic response in BaTiO3 films integrated on Si via heating and cooling rate control

Abstract Recent advancements in BaTiO3-based Si-integrated photonics devices have shown very large electro-optic responses, allowing for aggressive device scaling in both size and power. However, control of the crystallographic domain structure of high-quality epitaxial BaTiO3 films still remains a...

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Bibliographic Details
Main Authors: Marc Reynaud, Moaz Waqar, Chaojie Du, Agham B. Posadas, Xiaoqing Pan, Alexander A. Demkov
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Communications Materials
Online Access:https://doi.org/10.1038/s43246-025-00908-x
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Summary:Abstract Recent advancements in BaTiO3-based Si-integrated photonics devices have shown very large electro-optic responses, allowing for aggressive device scaling in both size and power. However, control of the crystallographic domain structure of high-quality epitaxial BaTiO3 films still remains a challenge. Here, we report on attempts to control the size of crystallographic domains and lattice relaxation profile of 150-nm-thick BaTiO3 films on Si grown by molecular beam epitaxy by varying the heating and cooling rates during the film growth process while maintaining strict epitaxial and stoichiometric control. The film’s crystallographic microstructure is visualized via plan-view transmission electron  microscopy to visualize the near surface lattice relaxation and crystallographic domain morphology. By carefully controlling the lattice relaxation evolution, the measured effective electro-optic response reaches values greater than 550 pm/V; it is observed that while the total electro-optic modulation of the films varies with heating/cooling rate, the effective response normalized to a-axis volume fraction does not.
ISSN:2662-4443