Electronic band structure of ZnO-rich highly mismatched ZnO{sub 1−x}Te{sub x} alloys

Journal Article · Mon Mar 02 00:00:00 EST 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4913840· OSTI ID:22412751

Ting, M.; Jaquez, M. ^[1]; Reis, R. dos ^[2]; Dubon, O. D. ^[1]; Mao, S. S. ^[3]; Yu, K. M. ^[1]; Walukiewicz, W. ^[1]

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1. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2. National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
3. Mechanical Engineering Department, University of California, Berkeley, California 94720 (United States)

We synthesized ZnO{sub 1−x}Te{sub x} 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 ZnO{sub 1−x}Te{sub x} alloys.

• OSTI ID: 22412751
• Journal Information: Applied Physics Letters, Vol. 106, Issue 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CONCENTRATION RATIO
COUPLING CONSTANTS
CRYSTAL GROWTH
ELECTRON MICROSCOPY
ELECTRONIC STRUCTURE
ENERGY BEAM DEPOSITION
EV RANGE
GRAIN ORIENTATION
LASER RADIATION
OPTICAL PROPERTIES
POLYCRYSTALS
PULSED IRRADIATION
RED SHIFT
TELLURIDES
VALENCE
ZINC OXIDES