Occurrence of 'accidental' InN quantum dots in indium gallium nitride/gallium nitride heterostructures

K. P. O'Donnell, R. W. Martin, M. E. White, S. Pereira, J. F.W. Mosselmans, M. J. Tobin, N. Grandjean, B. Damilano

Research output: Contribution to journalConference article

1 Citation (Scopus)

Abstract

Nakamura and co-workers were first to report the observation of spontaneously formed In-rich clusters in InGaN quantum wells (QW), using transmission electron microscopy (TEM) [1,2]. Some of the present authors have argued that the exceptional optical efficiency of nitride devices is due to the presence of nearly pure InN QD which form accidentally during crystal growth [3]. Pure InN QD with very small radius would emit light in the required spectral region, under the opposing effects of intrinsic electric fields and quantum confinement [4]. We have recently used extended X-ray absorption fine stucture to examine nanostructure [5] of molecular beam epitaxial (MBE) quantum boxes (QB), and photoluminescence excitation spectroscopy to examine their optical properties [6]. As revealed by AFM, QB are densely packed mesoscopic structures, 10-40 nm wide and 2-3 nm high. Our analysis of the QB EXAFS shows that the filling factor is of order 1%: each QB therefore contains a single QD. The optical evidence suggests that InN dots may be cubic. In contrast, TEM shows that QD in thick epilayers are sparsely distributed [7]. We re-examine recent TEM data on QW in the light of these results.

Original languageEnglish
Pages (from-to)13-17
Number of pages5
JournalMaterials Research Society Symposium - Proceedings
Volume737
Publication statusPublished - 25 Jul 2003
EventQuantum Confined Semiconductor Nanostructures - Boston MA, United States
Duration: 2 Dec 20025 Dec 2002

Keywords

  • semiconductor quantum dots
  • crystal growth
  • electric field effects
  • emission spectroscopy
  • Gallium nitride
  • heterojunctions
  • light emission
  • molecular beam epitaxy
  • nanostructured materials
  • optical properties
  • photoluminescence
  • semiconducting indium compounds
  • x ray spectroscopy

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