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Effects of lift-off and strain relaxation on optical properties of InGaN/GaN blue LED grown on 150 mm diameter Si (111) substrate

Journal of Crystal Growth
Publication Date
DOI: 10.1016/j.jcrysgro.2014.05.024
  • A1. Characterization
  • A1. High-Resolution X-Ray Diffraction
  • A3. Mocvd
  • B.1 Gan-On-Si
  • B1. Ingan/Gan Blue Led
  • Chemistry
  • Physics


Abstract We report on the effect of strain relaxations induced by lift-off in an InGaN/GaN multiple quantum wells (MQWs) blue light-emitting diode (LED) structure grown by metal-organic chemical vapor deposition (MOCVD) on a 150-mm diameter Si (111) substrate. To manage the lattice strain and, meanwhile, filter the threading dislocations, an AlN nucleation layer followed by a fourfold-step-graded AlGaN buffer together with multiple low-temperature AlN interlayers hasbeen employed, which results in a crack-free growth of 4.9-µm GaN on Si (111) in the studied LED structure. High-resolution x-ray diffraction (HRXRD) and micro-Raman spectroscopy reveal that MQWs are coherently grown on the GaN layer while the GaN layer is tensile strained on the Si (111) substrate. Lift-off by wet-chemical etching results in phonon softening of both the top-layer GaN and the InGaN within the QWs; meanwhile, a red-shift of ~11meV in the photoluminescence (PL) from the MQWs accompanied by a significant decrease (>4.9 times) in the PL-peak decay time is observed at room temperature. These observations are discussed and associated with the lift-off induced strain relaxations, which change the wafer curvature that in turn results in redistribution of in-plane stresses along the growth direction in the GaN-on-Si LED structure.

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