Flower-Like Internal Emission Distribution of LEDs with Monolithic Integration of InGaN-based Quantum Wells Emitting Narrow Blue, Green, and Red Spectra.

ABSTRACT: We report a phosphor-free white light-emitting diodes (LED) realized by the monolithic integration of In_0.18Ga_0.82N/GaN (438?nm, blue), In_0.26Ga_0.74N/GaN (513?nm, green), and In_0.45Ga_0.55N/In_0.13Ga_0.87N (602?nm, red) quantum wells (QWs) as an active medium. The QWs corresponding to blue and green light were grown using a conventional growth mode. For the red spectral emission, five-stacked In_0.45Ga_0.55N/In_0.13Ga_0.87N QWs were realized by the so-called Ga-flow-interruption (Ga-FI) technique, wherein the Ga supply was periodically interrupted during the deposition of In_0.3Ga_0.7N to form an In_0.45Ga_0.55N well. The vertical and lateral distributions of the three different light emissions were investigated by fluorescence microscope (FM) images. The FM image measured at a focal point in the middle of the n-GaN cladding layer for the red-emitting LED shows that light emissions with flower-like patterns with six petals are periodically observed. The chromaticity coordinates of the electroluminescence spectrum for the white LEDs at an injection current of 80?mA are measured to be (0.316, 0.312), which is close to ideal white light. In contrast with phosphor-free white-light-emitting devices based on nanostructures, our white light device exhibits a mixture of three independent wavelengths by monolithically grown InGaN-based QWs, thus demonstrating a more facile technique to obtain white LEDs.

SUBMITTER: Lee K 

PROVIDER: S-EPMC5541069 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature