Direct optical band gap measurement in polycrystalline semiconductors: A critical look at the Tauc method

Alex Dolgonos, Thomas O. Mason, Kenneth R. Poeppelmeier*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

184 Scopus citations


The direct optical band gap of semiconductors is traditionally measured by extrapolating the linear region of the square of the absorption curve to the x-axis, and a variation of this method, developed by Tauc, has also been widely used. The application of the Tauc method to crystalline materials is rooted in misconception-and traditional linear extrapolation methods are inappropriate for use on degenerate semiconductors, where the occupation of conduction band energy states cannot be ignored. A new method is proposed for extracting a direct optical band gap from absorption spectra of degenerately-doped bulk semiconductors. This method was applied to pseudo-absorption spectra of Sn-doped In2O3 (ITO) - converted from diffuse-reflectance measurements on bulk specimens. The results of this analysis were corroborated by room-temperature photoluminescence excitation measurements, which yielded values of optical band gap and Burstein-Moss shift that are consistent with previous studies on In2O3 single crystals and thin films.

Original languageEnglish (US)
Pages (from-to)43-48
Number of pages6
JournalJournal of Solid State Chemistry
StatePublished - Aug 1 2016


  • Band gap
  • Degenerate doping
  • Diffuse-reflectance
  • ITO
  • Photoluminescence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


Dive into the research topics of 'Direct optical band gap measurement in polycrystalline semiconductors: A critical look at the Tauc method'. Together they form a unique fingerprint.

Cite this