Acceptor complex signatures in oxygen-rich ZnO thin films implanted with chlorine ions

Spectroscopic identification of defects and impurities is crucial for understanding doping asymmetry issues in ZnO and, therefore, realization of true ZnO-based bipolar devices. Chlorine (Cl) is an amphoteric impurity in ZnO exhibiting acceptor behavior in the interstitial configuration and donor ac...

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Bibliographic Details
Published in:Journal of applied physics 2020-09, Vol.128 (12)
Main Authors: Azarov, Alexander, Galeckas, Augustinas, Venkatachalapathy, Vishnukanthan, Mei, Zengxia, Du, Xiaolong, Monakhov, Eduard, Kuznetsov, Andrej
Format: Article
Language:English
Subjects:
Applied physics
Chlorine
Coordination compounds
Electrical resistivity
Impurities
Optical properties
Photoluminescence
Spectral signatures
Thin films
Zinc oxide
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Summary:Spectroscopic identification of defects and impurities is crucial for understanding doping asymmetry issues in ZnO and, therefore, realization of true ZnO-based bipolar devices. Chlorine (Cl) is an amphoteric impurity in ZnO exhibiting acceptor behavior in the interstitial configuration and donor action once on substitutional oxygen sites (ClO). In its turn, the incorporation of Cl atoms depends on the material growth conditions and a ClO fraction should be suppressed in O-rich materials. In the present work, Cl ions were implanted into ZnO thin films synthesized under O-rich conditions. In contrast to a negligible effect of Cl incorporation to electrical conductivity, photoluminescence measurements revealed dramatic developments of optical properties with a strong acceptor-like spectral signature emerging after 900 °C anneals. We discuss the origins of a new excitonic I* line (3.355 eV) induced by Cl-implantation and propose two alternative defect models based on shallow acceptor and shallow donor complexes.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0021089