Mg-enhanced lateral overgrowth of GaN on patterned GaN/sapphire substrate by selective Metal Organic Vapor Phase Epitaxy


B. Beaumont, M. Vaille, G. Nataf, A. Bouillé, J.-C. Guillaume, P. Vénnègues, S. Haffouz, Pierre Gibart
Centre de Recherche sur l'Hétéroépitaxie et ses Applications, CRHEA-CNRS

This article was received on Wednesday, July 22, 1998 and accepted on Thursday, September 10, 1998.

Abstract

Selective and lateral overgrowth by Metal Organics Vapour Phase Epitaxy (MOVPE) was carried out until coalescence to produce smooth and optically flat thick GaN layers. A GaN epitaxial layer is first grown using atmospheric pressure Metalorganic Vapour Phase Epitaxy on a {0001} Al2O3. substrate. Then a 30Å silicon nitride dielectric film is deposited in-situ by reaction of silane and ammonia to form a selective mask. Afterwards, the openings and the figures in the dielectric films are achieved using standard photolithographic technology. Stripes openings in the mask, revealing free GaN surface, are aligned in the <10(-1)0> direction. Typical stripes spacing and width are 10 µm and 5 µm respectively. These patterned layers are further on used for epitaxial regrowth of GaN by MOVPE. The growth anisotropy and therefore the coalescence process is achieved by introducing (MeCp)2Mg in the vapour phase. A two-step process is reported which allows a dramatic reduction of threading dislocations density not only above the masked areas but also above the windows opened in the mask. With this process, very sharp bound exciton luminescence peaks are measured at low temperature in the overgrown GaN.

Outline

  • Introduction
  • Growth experiments
  • Preparation of the masked GaN templates
  • GaN regrowth
  • Regrowth of GaN with Mg doping
  • A two-step lateral overgrowth process
  • Assessment of the two-step GaN overgrowth.
  • Mg incorporation
  • Observation of the threading defects bending
  • Luminescence of GaN by epitaxial lateral overgrowth
  • Conclusion
  • Acknowledgments

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    Cite this article as: MRS Internet J. Nitride Semicond. Res. 3, 20(1998).

    last updated Friday, September 11, 1998 12:18:01 PM.

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