Unlocking the Single-Domain Epitaxy of Halide Perovskites

While the recent emergence of halide perovskites offer exciting opportunities for a range of thin-film electronics, current research on optoelectronic applications of inorganic lead-free halide perovskites has, to date, been less encouraging. These systems have likely been limited by the low degree of crystalline ordering and high defect density which has been linked in many semiconductors to impact carrier transport and recombination rate. The growth of epitaxial semiconductors and oxide perovskites has long since revolutionized the electronic and optic fields and continues to be exploited to uncover new quantum physics. The principles of true epitaxy have yet to be applied to halide perovskites. In this work we demonstrate the single-domain epitaxy of halide perovskites that is enabled by reactive vapor deposition. We uncover several new epitaxial phases via stoichiometry control that are stabilized with vastly differing lattice constants and accommodated via epitaxial rotation. We utilize precise epitaxial growth to fabricate quantum wells and extract the excited state Bohr radius. Moreover, we demonstrate the epitaxial lift-off and regrowth for further application. This work ultimately provides a new route to uncover the full potential of halide perovskites.