Flexible epitaxial LiNbO3 thin film with ferroelectricity and nonlinear optical response

Flexible or wearable devices are of great interests in the modern technologies, and oxide thin films are critical components for such applications. In this work, epitaxial LiNbO3 (LNO) thin film integrated on flexible mica substrate has been achieved. Al-doped ZnO (AZO) layer has been first deposited as buffer layer to obtain the epitaxial LNO film, furthermore AZO serves as bottom electrode for electrical measurement. The as-deposited LNO film exhibits high epitaxial quality with c-direction growth. The transmittance measurement indicates the high transparency of the film, similar to 85 % in visible range and similar to 90 % in near infrared region up to 1500 nm. The second harmonic generation (SHG) measurement confirms the nonlinearity of the flexible LNO film. The LNO/AZO/mica film also presents apparent ferroelectric response. Overall, the high-quality LNO integrated on flexible mica could be potentially applied in wearable optical and electrical devices.