Recovering the optical transitions in tin oxide thin films at room temperature using electroreflectance

H. A. Qayyum*, M. F. Al-Kuhaili, Tanvir Hussain, S. M.A. Durrani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Observing the optical transitions in Tin Oxide at room temperature is a difficult task because of its forbidden bandgap nature in bulk form. Moreover, it possesses the well know low emission efficiency issue in its reduced dimensional thin film structures. In this work, we use Electroreflectance (ER) method to recover the optical transitions in tin oxide thin films. A metal-oxide-metal geometry, with SnO2 film was sandwiched between two metal electrodes, was illuminated by the light under an external perturbation voltage. This results the well-enhanced critical points in the ER spectra with a suppressed featureless background. The characteristics of observed critical points are found using the third derivative functional form model. The points are identified as defect transition and surface exciton transition originated due to the presence of defect states formed by the oxygen vacancies. In addition to this, the free exciton transition, from deep of the valence band to the conduction band, is explicitly revealed by ER spectra of r-SnO2 film. A built-in electric field driven by external voltage is supposed to be the main factor for enhancing the critical points associated with optical transitions.

Original languageEnglish
Article number106985
JournalSuperlattices and Microstructures
StatePublished - Aug 2021

Bibliographical note

Publisher Copyright:
© 2021


  • Defect transitions
  • Electroreflectance
  • Free exciton transition
  • Optical transitions
  • SnO
  • Surface exciton transition
  • Third derivative functional form

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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