title: Dislocation Reduction and Stress Relaxation of GaN and InGaN Multiple Quantum Wells with Improved Performance via Serpentine Channel Patterned Mask.
abstract: The existence of high threading dislocation density (TDD) in GaN-based epilayers is a long unsolved problem, which hinders further applications of defect-sensitive GaN-based devices. Multiple-modulation of epitaxial lateral overgrowth (ELOG) is used to achieve high-quality GaN template on a novel serpentine channel patterned sapphire substrate (SCPSS). The dislocation blocking brought by the serpentine channel patterned mask, coupled with repeated dislocation bending, can reduce the dislocation density to a yet-to-be-optimized level of ∼2 × 10(5) to 2 × 10(6) cm(-2). About 80% area utilization rate of GaN with low TDD and stress relaxation is obtained. The periodical variations of dislocation density, optical properties and residual stress in GaN-based epilayers on SCPSS are analyzed. The quantum efficiency of InGaN/GaN multiple quantum wells (MQWs) on it can be increased by 52% compared with the conventional sapphire substrate. The reduced nonradiative recombination centers, the enhanced carrier localization, and the suppressed quantum confined Stark effect, are the main determinants of improved luminous performance in MQWs on SCPSS. This developed ELOG on serpentine shaped mask needs no interruption and regrowth, which can be a promising candidate for the heteroepitaxy of semipolar/nonpolar GaN and GaAs with high quality.
authors.affiliation: State Key Laboratory for Artificial Microstructure and Microscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors.forename: Qingbin
authors.initials: Q
authors.lastname: Ji
authors.affiliation: State Key Laboratory for Artificial Microstructure and Microscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, University of California ,Los Angeles, California 90095, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, University of California ,Los Angeles, California 90095, United States.
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, University of California ,Los Angeles, California 90095, United States.
authors.forename: Peichi
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Materials Science and Engineering, University of California ,Los Angeles, California 90095, United States.
authors.forename: Yahong
authors.initials: Y
authors.lastname: Xie
authors.affiliation: State Key Laboratory for Artificial Microstructure and Microscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors.forename: Tongxing
authors.initials: T
authors.lastname: Yan
authors.affiliation: State Key Laboratory for Artificial Microstructure and Microscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Artificial Microstructure and Microscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Chen
authors.affiliation: State Key Laboratory for Artificial Microstructure and Microscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Hu
keywords: GaN; InGaN quantum well; MOCVD; dislocation reduction; epitaxial lateral overgrowth; serpentine channel mask