Light-emitting diodes of “Warm” white luminescence on the basis of p-n heterostructures of the InGaN/AlGaN/GaN type coated with phosphors made of yttrium-gadolinium garnets

Abstract

Electroluminescence spectra and color characteristics of light-emitting diodes of white luminescence based on p-n heterostructures of the InGaN/AlGaN/GaN type with blue emission (λmax ≈ 455 nm) coated with phosphors of the type of aluminum-yttrium-gadolinium garnets activated with the Ce3+ ions are studied. The maximum in the excitation spectra of phosphors varies in the range 460–470 nm. The luminescence spectra of phosphors have the peaks from 530 to 590 nm and a width at half-maximum of intensity from 120 to 135 nm depending of the compound composition. The selection of intensities of blue and yellow-orange bands allows one to shift the coordinates of chromaticity of white light-emitting diodes to the region of “warm” luminescence with a correlated color temperature to TCC = 3000 K and maximum luminous efficiency up to 50 lm/W.