Photoluminescence studies of rare earth (Er, Eu, Tm) in situ doped GaN

The emission properties of rare earth (RE)-doped GaN are of significant current interest for applications in full color displays, white lighting technology, and optical communications. We are currently investigating the photoluminescence (PL) properties of RE (Er, Eu, Tm)-doped GaN thin-films prepared by solid-source molecular beam epitaxy. The most intense visible PL under above-gap excitation is observed from GaN:Eu (red: 622 nm) followed by GaN:Er (green: 537 nm, 558 nm), and then GaN:Tm (blue: 479 nm). In this paper, we present spectroscopic results on the Ga-flux dependence of the Er3+ PL properties from GaN:Er and we report on the identification of different Eu3+ centers in GaN:Eu through high-resolution PL excitation (PLE) studies. In addition, we observed an enhancement of the blue Tm3+ PL from AlGaN:Tm compared to GaN:Tm. Intense blue PL from Tm3+ ions was also obtained from AlN:Tm under below-gap pumping.