Heterogeneous Transfer of CsPbBr 3 Perovskite Epitaxial Films for Microcavity Lasers

Silicon photonics offers a scalable platform for integrated optical systems but is fundamentally limited by the lack of efficient on‐chip light sources due to silicon's indirect bandgap. Halide perovskites have emerged as promising gain materials; however, conventional polycrystalline films suffer from energetic disorder and limited cavity controllability. Here, we demonstrate deterministic microcavity engineering in high‐quality CsPbBr 3 epitaxial films grown via vapor‐phase epitaxy on mica. The films exhibit an ultralow Urbach energy of ∼16 meV without passivation, indicating minimal disorder. Artificial microdisk cavities fabricated by focused ion beam (FIB) etching support whispering‐gallery‐mode lasing with a quality factor of ∼2700 and a low threshold. Importantly, the epitaxial films can be transferred onto foreign substrates while preserving cavity modes and lasing characteristics. This approach decouples material growth from device integration and provides a scalable, CMOS‐compatible pathway toward on‐chip perovskite microlasers for photonic integrated circuits.