Correlative Study of Vibrational and Luminescence Properties of Zn2GeO4 Microrods.

The optical properties of zinc germanate microrods are investigated and correlated with vibrational modes of the crystalline structure. The samples are grown by a thermal evaporation method using ZnO and Ge as precursors. Polarized Raman spectroscopy and polarized micro‐photoluminescence techniques are applied in order to shed some light into the origin of the luminescence in Zn2GeO4. Oxygen defects are usually responsible for light emission in most of semiconducting oxides. Here, the authors report two luminescence bands at room temperature, a broad green one at about 2.4 eV and an ultraviolet one at 3.2 eV, which are of composed nature. In addition, the authors observe changes in the Raman and PL spectra recorded with polarizers oriented parallel or orthogonal to the microrod axis. The evolution of the luminescence bands in Zn2GeO4 and their correlation with the observed Raman modes (O‐Ge‐O and Ge‐O‐Zn vibration modes) are discussed in the framework of oxygen defects in the Zn2GeO4 structure. Vibrational modes and luminescence bands of Zn2GeO4 microwires are investigated. The correlation between vibrational modes in polarized Raman measurements and luminescence bands are explored. Besides the orientation of the wires, some insights into the oxygen defects that are involved in the luminescence bands are discussed. [ABSTRACT FROM AUTHOR]