Excitation Efficiency and Limitations of the Luminescence of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msup><mml:mi>Eu</mml:mi><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> Ions in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Ga</mml:mi><mml:mrow><mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:mrow></mml:math>
D. Timmerman, B. Mitchell, S. Ichikawa, J. Tatebayashi, M. Ashida, Y. Fujiwara
Abstract
The excitation efficiency and external luminescence quantum efficiency of trivalent ${\mathrm{Eu}}^{3+}$ ions doped into gallium nitride ($\mathrm{Ga}\mathrm{N}$) is studied under optical and electrical excitation. For small pump fluences, the excitation of ${\mathrm{Eu}}^{3+}$ ions is limited by an efficient carrier trap that competes in energy transfer from the host material. For large pump fluences, the limited number of high-efficiency ${\mathrm{Eu}}^{3+}$ centers and the small excitation cross section of the majority ${\mathrm{Eu}}^{3+}$ centers limit the quantum efficiency. At low temperatures, under optimal excitation conditions, the external luminescence quantum efficiency reaches a value of 46%. These results show the high potential for this material as an efficient light emitter and demonstrate the importance of excitation conditions on the light-output efficiency.