Effects on the amorphous Ga₂O₃ film surfaces by sub-IB-metal-nano-layers

Abstract

This work reports by the first time a method to control the geometry of Ga₂O₃ films nanocrystallites at 350 °C. The formation of controlled shaped nano-crystallites of γ-Ga₂O₃ from amorphous Ga₂O₃ films grown by RF-Sputtering at room temperature driven by nano-layers of group IB metals (Cu, Ag or Au) is studied. The reported results can be explained by the role of subsurface metal nano-layers and the non-equilibrium nature of the sputtering processes. To study the effects on the surface structure and their optical properties arrays of amorphous-Ga₂O₃/IB-metal/amorphous-Ga₂O₃ were annealed in dry N₂ atmosphere at 350 °C by 50, 100 and 150 min. The experimental results can be explained by the evolution of the amorphous character of the films amorphous films towards the nanocrystalline γ-Ga2O3 phase driven by the metal nano-layer seed nature. 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 according to FE-SEM analysis. The influence of the metal nano-layer is clearly seen by the shift of the plasmon frequency resonance produced by the Ga₂O₃/IB-metal/Ga₂O₃ arrays in the region from 400 to 600 nm caused by the modification of the interface Ga₂O₃/IB-metal produced by the applied annealing stages.