Selectively excited photoluminescence from Eu-implanted GaN

Abstract

The intensity of Eu-related luminescence from ion-implanted GaN with a 10 nm thick AlN cap, both grown epitaxially by metal organic chemical vapor deposition (MOCVD) is increased markedly by high-temperature annealing at 1300 ⁰C. Photoluminescence (PL) and PL excitation (PLE) studies reveal a variety of Eu centers with different excitation mechanisms. High- resolution PL spectra at low temperature clearly show that emission lines ascribed to ⁵D₀-⁷F₂ (similar to 622 nm), ⁵D₀-⁷F₃ (similar to 664 nm), and ⁵D₀-⁷F₁ (similar to 602 nm) transitions ach consist of several peaks. PL excitation spectra of the spectrally resolved components of the ⁵D₀-⁷F₂ multiplet contain contributions from above-bandedge absorption by the GaN host, a GaN exciton absorption at 356 nm, and a broad subedge absorption band centred at similar to 385 nm. Marked differences in the shape of the ⁵D₀-⁷F₂ PL multiplet are demonstrated by selective excitation via the continuum/exciton states and the below gap absorption band. The four strongest lines of the multiplet are shown to consist of two pairs due to different Eu3+ centers with different excitation mechanisms.