Thermal oxidation strategy for the synthesis of phase-controlled GeO2 and photoluminescence characterization

Abstract

We report the synthesis of trigonal and tetragonal phase GeO₂ films/microrods from a Ge wafer/powder by thermal oxidation. Both trigonal and tetragonal GeO₂ exhibit excitation-dependent luminescence. Trigonal GeO₂ exhibits strong green luminescence while tetragonal GeO₂ exhibits strong blue luminescence when excited with ultra-violet light. Yellow-red luminescence is observed when both the phases are excited with green light. The emission wavelength varies almost linearly with the excitation wavelength both for trigonal and tetragonal GeO₂. The variation is significant in the case of tetragonal GeO₂, indicating a potential wavelength converter material.