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Red‐Emitting InGaN‐Based Nanocolumn Light‐Emitting Diodes with Highly Directional Beam Profiles
Author(s) -
Yanagihara Ai,
Kishino Katsumi
Publication year - 2020
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201900771
Subject(s) - materials science , optoelectronics , light emitting diode , photonic crystal , diode , optics , refractive index , diffraction , lattice constant , wavelength , photonics , physics
Various InGaN/GaN pn‐junction nanocolumn arrays arranged in a triangle lattice are grown on the same substrate while changing the nanocolumn diameters ( D n‐GaN ) of the underlying n‐side GaN region under the lattice constant ( L ) of 340 nm. The nanocolumn diameter increases during the growth of the active InGaN and p‐side GaN regions. The periodic arrangement of nanocolumns leads to a photonic crystal effect. Redshift of the band edge wavelength, from 573 to 629 nm, is observed as D n‐GaN increases from 159 to 282 nm. This phenomenon can be explained by the fact that the larger filling factor increases the effective refractive index of the nanocolumn system, resulting in a redshift of the band edge. The light diffraction at the photonic band edge induces the directional radiation beam from the surface of the nanocolumn system. Using the nanocolumn array with D n‐GaN = 260 nm, the red‐emitting ( λ = 637 nm) nanocolumn light‐emitting diodes with the radiation angle of ±30° are demonstrated.