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Title: The improvement of GaN-based light-emitting diodes using nanopatterned sapphire substrate with small pattern spacing

Self-assembly SiO{sub 2} nanosphere monolayer template is utilized to fabricate nanopatterned sapphire substrates (NPSSs) with 0-nm, 50-nm, and 120-nm spacing, receptively. The GaN growth on top of NPSS with 0-nm spacing has the best crystal quality because of laterally epitaxial overgrowth. However, GaN growth from pattern top is more difficult to get smooth surface than from pattern bottom. The rougher surface may result in a higher work voltage. The stimulation results of finite-difference time-domain (FDTD) display that too large or too small spacing lead to the reduced light extracted efficiency (LEE) of LEDs. Under a driving current 350 mA, the external quantum efficiencies (EQE) of GaN-based LEDs grown on NPSSs with 0-nm, 50-nm, and 120-nm spacing increase by 43.3%, 50.6%, and 39.1%, respectively, compared to that on flat sapphire substrate (FSS). The optimized pattern spacing is 50 nm for the NPSS with 600-nm pattern period.
Authors:
; ; ; ; ; ;  [1] ;  [2]
  1. State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 (China)
  2. National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100080 (China)
Publication Date:
OSTI Identifier:
22251229
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 4; Journal Issue: 2; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTALS; ELECTRIC POTENTIAL; GALLIUM NITRIDES; LIGHT EMITTING DIODES; QUANTUM EFFICIENCY; SAPPHIRE; SILICA; SILICON OXIDES; STIMULATION; SUBSTRATES; SURFACES