Contactless electroreflectance studies of free exciton binding energy in Zn1-xMgxO epilayers

Contactless electroreflectance (CER) has been applied to study optical transitions in Zn1-xMgxO layers with magnesium concentration ≤44%. CER resonances related to free exciton and band-to-band transitions were clearly observed at room temperature. For ZnO the two transitions are separated by the en...

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Bibliographic Details
Published in:Applied physics letters 2013-12, Vol.103 (25)
Main Authors: Wełna, M., Kudrawiec, R., Kaminska, A., Kozanecki, A., Laumer, B., Eickhoff, M., Misiewicz, J.
Format: Article
Language:English
Subjects:
Applied physics
Binding energy
Excitons
Magnesium
Zinc oxide
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Summary:Contactless electroreflectance (CER) has been applied to study optical transitions in Zn1-xMgxO layers with magnesium concentration ≤44%. CER resonances related to free exciton and band-to-band transitions were clearly observed at room temperature. For ZnO the two transitions are separated by the energy of ∼65 meV, which is attributed to the free exciton binding energy in ZnO. Due to magnesium incorporation, the CER resonances broaden and shift to blue. The energy separation between excitonic and band-to-band transitions increases up to ∼100 meV when the magnesium concentration reaches 22%. For larger magnesium concentrations, CER resonances are significantly broadened and the excitonic transition is no longer resolved in the CER spectrum.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4851215