Electronic band structure of ZnO-rich highly mismatched ZnO1-xTex alloys

M. Ting, Roberto dos Reis, M. Jaquez, O. D. Dubon, S. S. Mao, K. M. Yu, W. Walukiewicz

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18 Scopus citations

Abstract

We synthesized ZnO1-xTex alloys with Te composition x < 0.23 by using pulsed laser deposition. Alloys with x < 0.06 are crystalline with a columnar growth structure while samples with higher Te content are polycrystalline with random grain orientation. Electron microscopy images show a random distribution of Te atoms with no observable clustering. We found that the incorporation of a small concentration of Te (x ∼ 0.003) redshifts the ZnO optical absorption edge by more than 1 eV. The minimum band gap obtained in this work is 1.8 eV for x = 0.23. The optical properties of the alloys are explained by the modification of the valence band of ZnO, due to the anticrossing interactions of the localized Te states with the ZnO valence band extended states. Hence, the observed large band gap reduction is primarily originating from the upward shift of the valence band edge. We show that the optical data can be explained by the band anticrossing model with the localized level of Te located at 0.95 eV above the ZnO valence band and the band anticrossing coupling constant of 1.35 eV. These parameters allow the prediction of the compositional dependence of the band gap as well as the conduction and the valence band offsets in the full composition range of ZnO1-xTex alloys.

Original languageEnglish (US)
Article number092101
JournalApplied Physics Letters
Volume106
Issue number9
DOIs
StatePublished - Mar 2 2015

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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    Ting, M., dos Reis, R., Jaquez, M., Dubon, O. D., Mao, S. S., Yu, K. M., & Walukiewicz, W. (2015). Electronic band structure of ZnO-rich highly mismatched ZnO1-xTex alloys. Applied Physics Letters, 106(9), [092101]. https://doi.org/10.1063/1.4913840