Optical and structural characteristics of virtually unstrained bulk-like GaN

Daniela Gogova, Alexander Kasic, Henrik Larsson, Bela Pécz, Rositza Yakimova, Björn Magnusson, Bo Monemar, Filip Tuomisto, Kimmo Saarinen, Claudio Miskys, Martin Stutzmann, Carsten Bundesmann, Mathias Schubert

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Bulk-like GaN with high structural and optical quality has been attained by hydride vapor-phase epitaxy (HVPE). The as-grown 330 μm-thick GaN layer was separated from the sapphire substrate by a laser-induced lift-off process. The full width at half maximum values of the X-ray diffraction (XRD) ω-scans of the free-standing material are 96 and 129 arcsec for the (10 -14) and (0002) reflection, respectively, which rank among the smallest values published so far for free-standing HVPE-GaN. The dislocation density determined by plan-view TEM images is 1-2 × 107 cm-2. Positron annihilation spectroscopy studies show that the concentration of Ga vacancy related defects is about 1.5 × 1016 cm-3. The high-resolution XRD, photoluminescence, μ-Raman, and infrared spectroscopic ellipsometry measurements consistently prove that the free-standing material is of high crystalline quality and virtually strain-free. Therefore it is suitable to serve as a substrate for stress-free growth of high-quality III-nitrides based device heterostructures.

Original languageEnglish (US)
Pages (from-to)1264-1268
Number of pages5
JournalJapanese Journal of Applied Physics
Issue number4 A
StatePublished - Apr 2004
Externally publishedYes


  • Bulk-like
  • GaN
  • HVPE
  • Optical and structural characteristics
  • Stress-free

ASJC Scopus subject areas

  • General Engineering
  • General Physics and Astronomy


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