Control of Eu Luminescence Centers by Codoping of Mg and Si into Eu-Doped GaN

Abstract

The effects of Mg and Si codoping on Eu luminescence properties have been investigated in Eu-doped GaN (GaN:Eu). The Mg codoping into GaN:Eu produced novel luminescence centers consisting of Eu and Mg, and increased photoluminescence (PL) intensity in Eu,Mg-codoped GaN (GaN:Eu,Mg). However, this increased PL intensity was quenched by thermal annealing in N2 ambient, which is due to activation of Mg acceptors. In GaN:Eu,Mg codoped additionally with Si (GaN:Eu,Mg,Si), on the other hand, the Eu–Mg centers disappeared, while an additional luminescence center appeared. Furthermore, the additional luminescence center showed no quenching under N2 annealing because Si donors compensated for the Mg acceptors in GaN. Thermal quenching of the luminescence center was also approximately half of that in GaN:Eu. These results indicate that the codoping with additional impurities in GaN:Eu is a powerful technique to control Eu luminescence centers for realization of improved device performance in red light-emitting diodes using GaN:Eu.