Growth and characteristics of self-assembly defect-free gan surface islands by molecular beam epitaxy

Kuang Yuan Hsu, Cheng Yu Wang, Chuan-Pu Liu

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1 Citation (Scopus)

Abstract

GaN surface nano-islands of high crystal quality, without any dislocations or other extended defects, are grown on a c-plane sapphire substrate by plasma-assisted molecular beam epitaxy. Nanoisland growth requires special conditions in terms of V/III ratio and substrate temperature, distinct from either film or nanocolumn growth. The insertion of a nitrided Ga layer can effectively improve the uniformity of the nano-islands in both shape and size. The islands are well faced truncated pyramids with island size ranged from 30 to 110 nm, and height ranged from 30 to 55 nm. On, the other hand, the density and facet of the GaN surface islands would be affected by the growth conditions. An increase of the V/III ratio from 30 to 40 led to an increase in density from 1.4 × 109 to 4.3 × 109 cm-2 and an evolution from {1-21-1} facets to {1-21-2} facets. The GaN layers containing the surface islands can moderate the compressive strain due to the lattice and thermal mismatch between GaN and c-sapphire. Conductive atomic force microscopy shows that the off-axis sidewall facets are more electrically active than those at the island center. The formation of the GaN surface islands is strongly induced by the Ehrlich-Schwoebel barrier effect of preexisting islands grown in the early growth stage. GaN surface islands are ideal templates for growing nano-devices.

Original languageEnglish
Pages (from-to)3393-3398
Number of pages6
JournalJournal of Nanoscience and Nanotechnology
Volume11
Issue number4
DOIs
Publication statusPublished - 2011 Dec 1

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Chemistry(all)
  • Biomedical Engineering
  • Materials Science(all)
  • Condensed Matter Physics

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