Franz-Keldysh effect in semiconductor built-in fields: Doping concentration and space charge region characterization

Yury Turkulets, Ilan Shalish

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Franz-Keldysh effect is expressed in the smearing of the absorption edge in semiconductors under high electric fields. While Franz [Z. Naturforsch. A 13, 484 (1958)] and Keldysh [Sov. Phys. JETP 7, 788 (1958)] considered a limited case of externally applied uniform electric field, the same effect may also be caused by built-in electric fields at semiconductor surfaces and interfaces. While in the first case, the bands are bent linearly, in the latter case, they are bent parabolically. This non-linear band bending poses an additional complexity that has not been considered previously. Here, we extend the linear model to treat the case of a non-linear band bending. We then show how this model may be used to quantitatively analyze photocurrent and photovoltage spectra to determine the built-in fields, the density of surface state charge, and the doping concentration of the material. We use the model on a GaN/AlGaN heterostructure and GaAs bulk. The results demonstrate that the same mechanism underlies the band-edge response both in photocurrent and photovoltage spectra and demonstrate the quantitative use of the model in contactless extraction of important semiconductor material parameters.

Original languageEnglish
Article number075102
JournalJournal of Applied Physics
Issue number7
StatePublished - 21 Aug 2018

ASJC Scopus subject areas

  • Physics and Astronomy (all)


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