Epitaxial Growth and Luminescent Properties of Mn2+-Activated ZnGa2O4 Films

The epitaxial growth and properties of Mn²⁺-doped ZnGa₂O₄ thin films on various single crystal substrates using pulsed laser deposition were investigated. Control of Zn/Ga stoichiometry required the use of a mosaic ZnGa₂O₄/ZnO ablation target to compensate for Zn loss due to evaporation. The photoluminescent intensity was a strong function of the Zn/Ga ratio, and also correlated with changes in the surface morphology. Superior photoluminescent intensity was attained from slightly Zn-deficient films which exhibit distinctive worm-like surface features. Enhanced photoluminescent intensity was observed in epitaxial films as compared to randomly-oriented polycrystalline deposits on glass substrates, suggesting an adverse effect of grain boundaries on luminescence properties.