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Suppression of near band edge emission in specially engineered ZnO twin nanorods

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Abstract

We report the synthesis of a unique zinc oxide nanorod structure in which an amorphous ZnO layer is sandwiched between two identical crystalline segments of ZnO. A simple hydrothermal reaction method was used for this purpose, which allowed us to tune the amorphous and crystalline sections of the nanorods via reaction temperature. A systematic study of the morphology and dimensions of the nanorods grown under various conditions was performed using a combination of scanning and transmission electron microscopy. Transmission electron microscopy (TEM) clearly showed an amorphous separation between the two crystalline segments. UV-vis absorption spectroscopy of the twin nanorods (TNRs) showed a redshift in the optical band gap as a function of the growth duration, indicating slightly stressed growth of the crystalline segments. For a longer growth duration, as the amorphous gap starts to get bridged by crystalline growth, redshift in optical band gap becomes constant. This confirms a true mechanical gap between the two crystalline segments of the nanorods. Temperature dependent photoluminescence (PL) spectra of the TNRs showed a variation in free exciton (FX) emission energy, which fitted very well to a model incorporating lattice dilation in addition to the standard electron–phonon interactions. At low temperatures (below ∼180 K) we observed the appearance of visible emission peaks due to localization of defect levels. A loss in the near band edge emission intensity was observed at low temperatures, commensurate with the appearance of defect emission in the visible range.

Graphical abstract: Suppression of near band edge emission in specially engineered ZnO twin nanorods

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Publication details

The article was received on 24 Mar 2017, accepted on 26 Apr 2017 and first published on 26 Apr 2017


Article type: Paper
DOI: 10.1039/C7CP01880K
Citation: Phys. Chem. Chem. Phys., 2017, Advance Article
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    Suppression of near band edge emission in specially engineered ZnO twin nanorods

    A. Singh, K. Senapati, B. Satpati and P. K. Sahoo, Phys. Chem. Chem. Phys., 2017, Advance Article , DOI: 10.1039/C7CP01880K

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