Synthesis, luminescence and micro-Raman study of In2Ge2O7 nanobelts and nanowires

Indium germanate (In2Ge2O7) nanobelts and nano- and microwires have been synthesized by a thermal evaporation-deposition method and their luminescence properties have been investigated. High-resolution transmission electron microscopy shows the growth direction of the nanobelts. Cathodoluminescence in the scanning electron microscope and photoluminescence show the existence of a broad complex emission band with several components in the range 1.70-2.80 eV and a band at 3.20-3.30 eV. Comparison of the observed luminescence with the luminescence of GeO2 suggests that some of the components are related to the presence of Ge2O7 groups in the germanate crystal structure and not to the sheets of InO6 octahedra of the structure. Waveguiding behaviour of In2Ge2O7 nano- and microwires has been demonstrated under excitation with 325 nm light. Raman spectra of the nanobelts have characteristic peaks which could enable to correlate specific Raman features with the presence of In2Ge2O7 and to use this technique for indium germanate assessment.