Cathodoluminescence of rare earth implantedGa2O3 andGeO2 nanostructures

Abstract

Rare earth (RE) doped gallium oxide and germanium oxide micro- and nanostructures,mostly nanowires, have been obtained and their morphological and opticalproperties have been characterized. Undoped oxide micro- and nanostructureswere grown by a thermal evaporation method and were subsequently doped withgadolinium or europium ions by ion implantation. No significant changes in themorphologies of the nanostructures were observed after ion implantation andthermal annealing. The luminescence emission properties have been studied withcathodoluminescence (CL) in a scanning electron microscope (SEM). Bothβ-Ga2O3 andGeO2 structuresimplanted with Eu show the characteristic red luminescence peak centered at around 610 nm, due tothe 5D0–7F2 Eu3 + intraionictransition. Sharpening of the luminescence peaks after thermal annealing is observed in Eu implantedβ-Ga2O3, which is assigned tothe lattice recovery. Gd3 + as-implanted samples do not show rare earth related luminescence. After annealing, optical activationof Gd3 + is obtained in both matrices and a sharp ultraviolet peak centered at around 315 nm, associated withthe Gd3 + 6P7/2–8S7/2 intraionic transition, is observed. The influence of the Gd ion implantation and theannealing temperature on the gallium oxide broad intrinsic defect band has beenanalyzed.