Double surface effect causes a peak in band-edge photocurrent spectra: A quantitative model

Yury Turkulets, Tamar Bick, Ilan Shalish

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Band-edge photocurrent spectra are typically observed in either of two shapes: a peak or a step. In this study, we show that the photocurrent band-edge response of a GaN layer forms a peak, while the same response in GaN nanowires takes the form of a step, and both are red-shifted to the actual band-edge energy. This apparent inconsistency is not limited to GaN. The physics of this phenomenon has been unclear. To understand the physics behind these observations, we propose a model that explains the apparent discrepancy as resulting from a structure-dependent surface effect. To test the model, we experiment with a GaAs layer, showing that we can deliberately switch between a step and a peak. We use GaAs because it is available at a semi-insulating doping level. We demonstrate that using this quantitative model one may obtain the exact band-edge transition energy, regardless of the red-shift variance, as well as the density of the surface state charges that cause the red shift. The model thus adds quantitative features to photocurrent spectroscopy.

Original languageEnglish
Article number365104
JournalJournal Physics D: Applied Physics
Issue number36
StatePublished - 17 Aug 2016


  • FranzKeldysh effect
  • GaN
  • exciton
  • nanowires
  • photocurrent spectroscopy
  • spectral photoconductivity
  • surface states

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films


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