Growth of delafossite CuAlO₂ single crystals in a reactive crucible

Delafossite oxide CuAlO₂ has received great attention as a promising p-type conducting oxide. In this work, high-quality CuAlO₂ single crystals with a size of several millimeters (mm) are successfully synthesized with a reactive crucible melting method. The crystals are characterized by x-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, transport measurement, and magnetic susceptibility measurement. The CuAlO₂ single crystals show semiconducting behavior with hole carriers, which is consistent with other crystals grown by the conventional slow-cooling method. This growth method we reported here eliminates the process of removing the remaining flux, allowing easy access to the high-quality single crystals. This new approach to growing high-quality delafossite oxide CuAlO₂ with a few mm size is important for new technologies that demand p-type semiconductor-based device fabrication.