Epitaxial Lift‐Off of Centimeter‐Scaled Spinel Ferrite Oxide Thin Films for Flexible Electronics

Abstract

Mechanical flexibility of electronic devices has attracted much attention from research due to the great demand in practical applications and rich commercial value. Integration of functional oxide materials in flexible polymer materials has proven an effective way to achieve flexibility of functional electronic devices. However, the chemical and mechanical incompatibilities at the interfaces of dissimilar materials make it still a big challenge to synthesize high-quality single-crystalline oxide thin film directly on flexible polymer substrates. This study reports an improved method that is employed to successfully transfer a centimeter-scaled single-crystalline LiFe O thin film on polyimide substrate. Structural characterizations show that the transferred films have essentially no difference in comparison with the as-grown films with respect to the microstructure. In particular, the transferred LiFe O films exhibit excellent magnetic properties under various mechanical bending statuses and show excellent fatigue properties during the bending cycle tests. These results demonstrate that the improved transfer method provides an effective way to compose single-crystalline functional oxide thin films onto flexible substrates for applications in flexible and wearable electronics.

Progress, Outlook, and Challenges in Lead‐Free Energy‐Storage Ferroelectrics

“…In recent years, a modern lift-off technology has enabled such thin films' transferring to other more substrates, broadening the operating environment of epitaxial thin films. [160,161] Energy storage parameters for epitaxial thin films grown on both rigid and flexible substrates have been summarized in Table 5.…”

“…Liu et al have provided us a way for flexible application by dissolving-transferring technique, while the film area has been limited in centimeter scale. [160,161] In order to obtain larger scale flexible film, flectional substrate such as fluorophlogopite mica has been presented. Figure 22a.…”

Atomic Scale Understanding of the Epitaxy of Perovskite Oxides on Flexible Mica Substrate

“…These flexible devices depend strongly on the functionality of bendable and stretchable materials, which can be realized by freestanding thin films and/or growing films on flexible substrates . Several approaches have been developed to obtain such flexible thin films, including the releasing‐and‐transferring technique and the direct growth of thin films on flexible substrates, such as polymer materials and metal foils …”

Mechanical Strain‐Tunable Microwave Magnetism in Flexible CuFe2O4 Epitaxial Thin Film for Wearable Sensors

“…Hence, flexible epitaxial thin film is an essential component of wearable sensors . Recently, some flexible ferromagnetism, ferroelectricity, conductivity, and ME coupling epitaxial thin films have been successfully obtained by using flexible substrate (Mica) or transfer method (peel epitaxial thin films from their hard substrates), such as ITO/Mica, Fe 3 O 4 /Mica, BiFeO 3 ‐CoFe 2 O 4 /Mica, PZT/Mica, BaTi 0.95 Co 0.05 O 3 /Mica, LiFe 5 O 8 , and CoFe 2 O 4 etc . However, the flexible microwave magnetism epitaxial thin films are still scarce up to now.…”