Dislocation reduction in GaN film using Ga-lean GaN buffer layer and migration enhanced epitaxy

Yuen Yee Wong, Edward Yi Chang, Yue Han Wu, Mantu K. Hudait, Tsung Hsi Yang, Jet Rung Chang, Jui Tai Ku, Wu-Ching Chou, Chiang Yao Chen, Jer Shen Maa, Yueh Chin Lin

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A GaN buffer layer grown under Ga-lean conditions by plasma-assisted molecular beam epitaxy (PAMBE) was used to reduce the dislocation density in a GaN film grown on a sapphire substrate. The Ga-lean buffer, with inclined trench walls on its surface, provided an effective way to bend the propagation direction of dislocations, and it reduced the dislocation density through recombination and annihilation processes. As a result, the edge dislocation density in the GaN film was reduced by approximately two orders of magnitude to 2 × 108 cm- 2. The rough surface of the Ga-lean buffer was recovered using migration enhanced epitaxy (MEE), a process of alternating deposition cycle of Ga atoms and N2 radicals, during the PAMBE growth. By combining these two methods, a GaN film with high-crystalline-quality and atomically-flat surface can be achieved by PAMBE on a lattice mismatch substrate.

Original languageEnglish
Pages (from-to)6208-6213
Number of pages6
JournalThin Solid Films
Issue number19
StatePublished - 29 Jul 2011


  • Atomic force microscopy
  • Dislocations
  • Ga-lean gallium nitride
  • Gallium nitride
  • High-resolution X-ray diffraction
  • Migration enhanced epitaxy
  • Molecular beam epitaxy
  • Transmission electron microscopy

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