Thermal growth and optical properties of zinc germanate microrods

Zinc germanate, Zn₂GeO₄, is a wide band gap ternary oxide with properties of interest in the fields of photodetection, catalysis, luminescence and others. In this work Zn₂Ge₂O₄ microrods have been synthesized by a catalyst free evaporation-deposition method and structural and optical characterization has been carried out. Luminescence of the rods has been studied by photoluminescence (PL) and cathodoluminescence (CL) in the scanning electron microscope (SEM). Luminescence spectra consist of a complex band at about 2.40 eV and a high energy band at 3.23 - 3.45 eV which is only revealed under high excitation conditions. Modulations corresponding to optical resonances are observed in the luminescence and they are explained by the existence of Fabry-Perot modes in the cross sections of the rods. Micro Raman spectra show different bands that appear to be characteristic of vibrations in Zn₂GeO₄.