[20p-E302-1~17] 13.8 Optical properties and light-emitting devices

▲ [20p-E302-16] Excitation dynamics and efficiency of luminescence of Eu in GaN

〇Dolf Timmerman¹, Masaaki Ashida¹, Shuhei Ichikawa¹, Jun Tatebayashi¹, Yasufumi Fujiwara¹ (1.Osaka Univ.)

Keywords:Rare earth, PL QE, Carrier dynamics

While blue and green LEDs based on GaN are already successfully commercialized, red emission from these materials is still lacking and preventing monolithic full-color displays. Eu-doped GaN attracts special attention due to its intense emission and temperature insensitive wavelength stability around 622 nm. In order to improve the luminescence output of these materials it is important to understand the energy transfer dynamics from the GaN-host to Eu ions, as well as the limitations hereof. Here we present a comprehensive study on the ultrafast carrier dynamics, energy transfer mechanism and luminescence quantum efficiency (QE) of this material. It is shown that the QE is strongly dependent on the excitation conditions and can reach nearly 30% at room temperature and up to 50% at low temperature. This high efficiency is a result of efficient carrier trapping and energy transfer. The timescales involved have been determined by ultrafast spectroscopy and are presented.