Two colour experiments in Eu3+ implanted GaN

Abstract : Two colour experiments can be used to study the excitation mechanisms of rare-earth ions in rare-earth doped wide-bandgap semiconductors as well as the quenching of their photoluminescence (PL). The combined excitation of Eu3+ implanted GaN samples with a pulsed laser and a CW laser, corresponding, respectively, to a below bandgap excitation and to an above bandgap excitation, is investigated. A strong quenching of the rare-earth (RE) luminescence is observed with both lasers compared to the excitation with only one laser. The dependence of the Eu3+ 5D0 lifetime quenching with the emission wavelength and excitation density of the CW laser is presented. The results are explained within the frame of a model describing the occurrence of an Auger effect between excited Eu ions and free carriers created by the CW laser.