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InGaN/AlGaN stress compensated superlattices coherently grown on semipolar ( 11 2 ¯ 2 ) GaN substrates
Author(s) -
Nishinaka Junichi,
Funato Mitsuru,
Kido Ryohei,
Kawakami Yoichi
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552336
Subject(s) - materials science , optoelectronics , lasing threshold , superlattice , photoluminescence , gallium nitride , laser , ultraviolet , optics , nanotechnology , layer (electronics) , wavelength , physics
The crystal growth and optical properties of semipolar (11 2 ¯2 ) InGaN/AlGaN stress‐compensated superlattices (SCSLs) are investigated. X‐ray diffraction and transmission electron microscopy reveal that appropriately designed 125‐period In 0.2 Ga 0.8 N (1 nm)/Al 0.2 Ga 0.8 N (3 nm) SCSLs grow coherently on (11 2 ¯2 ) GaN substrates. The refractive index of a fabricated SCSL is lower than that of GaN in the green spectral range; indicating that SCSLs have potential as the cladding layers in green laser diodes (LDs). Photoluminescence appears in the near ultraviolet (UV) range without significant in‐plane optical anisotropy because the two topmost valence bands are close together in coherent semipolar InGaN with an experimentally determined In composition of 28%. This nearly isotropic nature allows photo‐pumped lasing in a cavity with ( 11 ¯00 ) cleaved mirrors; suggesting potential applications of SCSLs in UV LD active layers. Schematic of InGaN/AlGaN SCSLs on GaN substrates. Balanced tensile and compressive stresses in AlGaN and InGaN, respectively, realize coherent growth of thick SCSLs.