Optical absorption dependence on composition and thickness of In xGa 1 - XN (0.05 < × < 0.22) grown on GaN/sapphire

Balakrishnam R. Jampana, Conan R. Weiland, Robert L. Opila, Ian T. Ferguson, Christiana Honsberg

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


We report the change in optical absorption properties of InGaN epilayers around the critical layer thickness determined from X-ray diffraction. Detrimental sub-band gap absorption is observed in InGaN thin films grown beyond the critical layer thicknesses, and is caused by localized electric fields around extended crystalline defects and aided by V-defects through light channeling. The photoluminescence response from InGaN thin films, grown beyond the critical layer thickness, is reduced owing to absorption of the incident laser light by non-radiative recombination extended crystalline defects. The formation of V-defects is observed to occur beyond the critical layer thickness and continues to grow in areal coverage aiding in sub-band gap absorption. This optical behavior sets constraints to be incorporated in the design of InGaN solar cell and requirement for improvement in epitaxial growth techniques to reduce V-defects.

Original languageEnglish (US)
Pages (from-to)6807-6812
Number of pages6
JournalThin Solid Films
Issue number22
StatePublished - Sep 1 2012


  • Crystalline defects
  • Indium gallium nitride
  • Optical absorption
  • X-ray diffraction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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