[20p-S223-9~17] 13.9 Optical properties and light-emitting devices

[20p-S223-11] Analysis of emission centers in GaN:Eu red LED using three-dimensional mapping

〇Masashi Ishii¹, Atsushi Koizumi², Yasufumi Fujiwara² (1.NIMS, 2.Osaka Univ.)

Keywords:GaN:Eu,LED,Emission center

A pulse-driven emission-spectroscopy (PDES) mapping technique is used to investigate the bright emission centers in Eu-doped GaN (GaN:Eu) red light emitting diodes (LED). The LEDs are operated in pulse-driven mode and the emission spectra are acquired for a range of pulse frequencies. This ensemble of emission spectral data yields a three-dimensional mapping that allows the origin of emission lines to be identified by visual inspection. The identification was achieved even for a weak ⁵D₀ → ⁷F₃ transition in conventional photoluminescence measurements. A peculiar split is observed in the ⁵D₀ → ⁷F₃ transition for the bright emission center referred to as OMVPE 8. Despite the unique transition at this emission center, the emission efficiencies for the ⁵D₀ → ⁷F₃ and ⁵D₀ → ⁷F₂ transitions were identical. This finding indicates that the excitation of the emission centers, rather than the radiative transitions, is the limiting process that determines the GaN:Eu red LED brightness.