In this work we report the controlled crystallization of amorphous Ga2O3 grown by RF-Sputtering at room temperature induced by nano-layers of group IB metals (Cu, Ag or Au). The results can be explained by the role of subsurface metal nano-layers and the non-equilibrium nature of the sputtering processes. To study the influence of the metal nano-layers the surface structure and the optical properties of bilayer arrays of amorphous-Ga2O3/IB-metal films were annealed in dry N2 atmosphere at 350 °C by 50, 100, 150 and 200 min. The experimental results can be explained by the evolution of the amorphous character of the films towards the nanocrystalline phase driven by the nature of a metal nano-layer seed. As the annealing time was increased the transition from amorphous-Ga2O3 to the nanocrystalline γ-Ga2O3 phase was detected by X-ray diffraction analysis. The transition to the nanocrystalline γ-Ga2O3 is demonstrated by the formation of octahedral, triangle and ball shape nanocrystallites with sizes of ~5 to 50 nm studied by FE-SEM analysis. The optical properties measured on the Ga2O3/IB-metal films arrays clearly shown the plasmon frequency resonance in the region from 400 to 600 nm caused by the evolution of the metal nanostructures produced by the applied annealing stages. This work demonstrates by the first time a method to control the nanocrystallites geometry of Ga2O3 films at films at 350 °C.

Effect on the amorphous Ga2O3 films surfaces by metals sub-IB-metal-nano-layers

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