Heteroepitaxial growth of Ga2O3 thin films on nickel-nanodot-induced buffer layers for solar-blind ultraviolet photodetector applications

Heteroepitaxial growth of gallium oxide (Ga2O3) thin films has been conducted on nickel (Ni)-nanodot-induced buffer layers using a mist chemical vapor deposition. The separation degree and droplet size of the Ni nanodots on sapphire substrates were controlled through a thermal annealing process, thereby being used as templates for the Ga2O3 thin-film growth. The growth of the inverted cone-shaped epsilon-Ga2O3 polymorph was observed on the nanodots while the alpha-Ga2O3 polymorph was grown on the sapphire substrate without nanodots, ultimately a thin film with a mixture of epsilon and alpha polymorphs can be achieved. By comparing photoresponses of metal-semiconductor-metal photodetectors fabricated on the thin film with the mixed polymorphs and on a single-crystalline alpha-Ga2O3 film, a promising template for using solar-blind photo-detecting applications has been verified.