Depth Profiling of Defects in Crystal‐Ion‐Sliced Single‐Crystalline LiNbO ₃ Thin Films With Bragg Reflector Structure

The single‐crystalline LiNbO 3 (LN) thin film with Bragg reflector structure can confine the acoustic wave energy to improve the performance of the acoustic devices, such as quality factor. Although single‐crystalline LN thin films fabricated by the crystal‐ion‐slicing (CIS) technique exhibit excellent crystal quality, the defects induced by CIS remain non‐negligible. Therefore, a comprehensive understanding of the depth distribution of defects within exfoliated thin films with Bragg reflector structure is significant. In this study, a X‐cut single‐crystalline LN thin film with SiO 2 /Ta 2 O 5 Bragg reflector structure was fabricated by CIS. Different layers at different depths in the LN thin film were obtained by Ar + etching and were characterized to analyze the depth profile of defects. The results reveal that the thin film contains severely damaged layer and vacancy‐type defects layer. Removing the severely damaged layer is insufficient to obtain high‐quality thin film. Removal or recovery of the vacancy‐type defects layer is also essential. This work demonstrates the depth distribution of the defects in the thin film and provides guidance for damage removal and recovery processes to obtain a high‐quality single‐crystalline LN thin film with Bragg reflector structure, which is vital for developing high‐performance acoustic devices.