Catalyst-assisted heteroepitaxial strategy for highly ordered β -Ga 2 O 3 nanoarrays and their optical property investigation

In this work, we demonstrate the growth of highly orderedβ-Ga₂O₃nanoarrays with (001) preferred growth plane for the first time through a facile heteroepitaxial strategy using metal Ga and c-sapphire as Ga precursor and monocrystalline substrate. The (001) preferred growth plane means that theβ-Ga₂O₃nanowires grow along the normal direction of the (001) plane. Theβ-Ga₂O₃nanoarrays along (001) preferential plane exhibit inclined six equivalent directions that correspond to the six crystallographic symmetry of (0001)α-Al₂O₃. High-resolution transmission electron microscopy analyses confirm the good crystallinity and the existence of unusual epitaxial relationship of {310}_β-Ga2O3ǁ (0001)_α-Al2O3and <001>_β-Ga2O3or <132>_β-Ga2O3ǁ [11¯00]_α-Al2O3. UV-vis and cathodoluminescence measurements reveal the wide band gap of 4.8 eV and the strong UV-blue luminescence (300-500 nm) centered at ∼388 nm. Finally, the luminescence mechanism is further investigated with the assistance of x-ray photoelectron spectroscopy. The heteroepitaxial strategy of highly orderedβ-Ga₂O₃nanoarrays in this work will undoubtedly pave a solid way toward the fundamental research and the applications of Ga₂O₃nanodevices in optoelectronic, gas sensor, photocatalyst and next-generation power electronics.