Visible cathodoluminescence of Er ions in ß-Ga_2O_3 nanowires and microwires

Abstract

Erbium doped ß-Ga_2O_3 nanowires and microwires have been obtained by a vapour-solid process from an initial mixture of ß-Ga_2O_3 and Er_2O_3 powders. X-ray diffraction (XRD) analysis reveals the presence of erbium gallium garnet as well as ß-Ga_2O_3 phases in the microwires. Scanning electron microscopy (SEM) images show that the larger microwires have a nearly rectangular cross-section. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) analysis show good crystal quality of the ß-Ga_2O_3 nanowires. The nanostructures have been studied by means of the cathodoluminescence technique in the scanning electron microscope. Er intraionic blue, green and red emission lines are observed in luminescence spectra even at room temperature, which confirms the optical activity of the rare earth ions in the grown structures. Mapping of the main 555 nm emission intensity shows a non-homogeneous distribution of Er ions in the microstructures.