Epitaxial growth of β-Ga2O3 nanocolumns on MgO substrate

Crystal structure of Ga2O3 nanocolumns grown on MgO substrate is analyzed by electron microscopy and electron diffraction study. The nanocolumns have β-Ga2O3 structure and the growth direction is [0 0 1] directions. A thin γ-Ga2O3 layer grows on the substrate to relax the lattice misfit between MgO and β-Ga2O3. The bottom layer of the γ form layer is disordered by {1 1 0} stacking faults. Poly crystalline structure that consists of β-Ga2O3 and γ-Ga2O3 nanocrystals exists between the β form nanocolumns and the γ form layer. The γ form changes gradually to the β form growing up to the nanocolumn. Though various crystal forms appear in a specimen, oxygen cubic close-packed lattice in crystal structures has always the same orientation in all layers including the MgO substrate.