¹Institute of Physics, National Academy of Sciences of Ukraine
²Ukrainian State Mykhailo Drahomanov University, Kyiv, Ukraine
³Institute for Nuclear Research, National Academy of Sciences of Ukraine
*Corresponding author e-mail: oksana.budnyk@gmail.com

Abstract. The emission spectra of InGaN/GaN white light emitting diodes (WLEDs) were measured. The main emission components were a LED blue line with λmax = 443 nm and a wide double band in the range of 500…650 nm of the secondary emission of AIT-YAG phosphor (Ce). The observed non-monotonic temperature dependence of the emission was attributed to the electric-field screening effect by mobile carriers as well as to thermal quenching due to the increased density of the phonon gas. The power conversion factor of phosphor emission increased in the temperature range of 200…290 K. The total energy losses for the Stokes shift were 82% and 77% for the first (blue) and the second band, respectively. The decrement of emission at high injection currents (over 20 mA) was attributed to ballistic transfer of carriers above the quantum wells and subsequent non-radiative recombination in the barrier layers. The existence of long-term relaxation processes in the white LEDs was assumed to be due to the accumulation of In atoms. Electron beam irradiation caused WLED efficiency degradation due to the introduction of deep traps in the quantum well region. The radiation resistance of the AIT-YAG phosphor was ~1.6 times higher than that of the InGaN part.

Keywords:white LEDs, InGaN, AIT-YAG, gamma-irradiation, spectral characteristics of white LEDs.

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