Excitonic effects at the temperature-dependent direct bandgap of Ge

Carola Emminger, Nuwanjula S. Samarasingha, Melissa Rivero Arias, Farzin Abadizaman, José Menéndez, Stefan Zollner

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The temperature dependence of the complex dielectric function ∈1 1∈2 of bulk Ge near the direct bandgap was investigated with spectroscopic ellipsometry at temperatures between 10 and 710 K. Second derivatives of the dielectric function with respect to energy are obtained using a digital linear filter method. A model that incorporates excitonic effects using the Tanguy model for the Hulthén potential [C. Tanguy, Phys. Rev. B 60, 10660 (1999)] was used to fit the dielectric function and its second derivatives simultaneously. Using k â p theory and literature values for effective masses, reasonable agreement with the experiment is obtained for I 2 up to room temperature using the direct bandgap and its broadening as the only adjustable parameters.

Original languageEnglish (US)
Article number165701
JournalJournal of Applied Physics
Issue number16
StatePublished - Apr 28 2022

ASJC Scopus subject areas

  • General Physics and Astronomy


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