Optical Characterization of Erbium Doped III-Nitrides Prepared by Metalorganic Molecular Beam Epitaxy

Abstract

AbstractWe are currently engaged in a systematic study of the optical properties of Er doped III-nitrides prepared by metalorganic molecular beam epitaxy (MOMBE). Under below-gap excitation it was observed that GaN: Er samples with [O]∼1020 cm-3 and [C]∼1021 cm-3 luminesce at 1540 nm with an intensity of more than two orders of magnitude greater than samples with low oxygen and carbon concentrations (< 1019 cm-3). Associated with the different oxygen and carbon concentrations were different thermal quenching behaviors and below-gap absorption bands. Interestingly, for above-gap excitation only small differences in absolute Er3+ PL intensity and quenching behavior were observed for samples of varying 0 and C content. Initial lifetime studies were performed and showed a rather unusual short decay time of ∼100 μts at room temperature. In order to gain more insight in the Er3+ PL, a comparison of the integrated PL intensity and lifetime was performed for the temperature range 15-500K. The result reveals that the Er3+ PL quenches above room temperature due to the onset of non-radiative decay and the reduction in excitation efficiency. All samples were also investigated for visible luminescence. Red luminescence was observed from GaN: Er on sapphire substrates under below-gap excitation.