Halide Vapor Phase Epitaxy α‐ and ε‐Ga 2 O 3 Epitaxial Films Grown on Patterned Sapphire Substrates
The growth of Ga2O3 films by halide vapor phase epitaxy on plain and cone‐shaped patterned sapphire substrates (PSS) is reported. The obtained specimens are characterized by X‐ray diffraction, transmission electron microscopy, cathodoluminescence, optical transmission spectroscopy, and current–voltage measurements. Both types of Ga2O3 layers are of reasonably high crystal qualities; their physical properties, however, are very different. Under the same conditions, the growth on plain substrates results in a continuous α‐Ga2O3 layer, whereas the growth on PSS produces a regular array of α‐Ga2O3 columns on top of the sapphire cones with the space between them filled with ε‐Ga2O3. Ga2O3 films grown on plain sapphire are insulating; in contrast, Ga2O3 films grown on PSS are conducting. It is found that the conductivity of Ga2O3 on PSS follows the Arrhenius law with the activation energy of 0.33 eV. New luminescent bands for α‐ and ε‐phases are found. Spectral components of the defect‐related luminescence for α‐ and ε‐ phases are identified.
