Identification of extended defect and interface related luminescence lines in polycrystalline ZnO thin films grown by sol–gel process. Issue 51 (9th May 2016)

• Record Type: Journal Article
• Authors: Guillemin, Sophie; Consonni, Vincent; Rapenne, Laetitia; Sarigiannidou, Eirini; Donatini, Fabrice; Bremond, Georges
• Is Part Of: RSC advances. Volume 6:Issue 51(2016)
• Page Start: 44987
• Page End: 44992
• Publication Date: 2016-05-09
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra04634g
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The luminescence lines related to extended defects and interfaces in polycrystalline ZnO thin films grown by sol–gel process are investigated by combining photoluminescence and cathodoluminescence imaging with high-resolution transmission electron microscopy. Abstract : The luminescence lines related to extended defects and interfaces in polycrystalline ZnO thin films grown by sol–gel process are deeply investigated by combining temperature-dependent photoluminescence and cathodoluminescence imaging with high-resolution transmission electron microscopy. A typical broad emission band is shown in the range of 3.316 to 3.333 eV and mainly consists of two distinct contributions. At high energy, a 3.333 eV line is associated with interfaces ( i.e., free surfaces and grain boundaries) and predominates for small ZnO nanoparticles owing to their high density. The intensity ratio of the excitonic to interface-related transitions is low in this first configuration and the 3.333 eV line is characterized by an activation energy of 12.0 ± 1.2 meV and a Huang-Rhys factor of 0.54 ± 0.05 at 12 K. At low energy, a 3.316 eV line is attributed to basal plane stacking faults that are mostly of I1 -type and prevail for large ZnO nanoparticles. The 3.316 eV line is characterized by an activation energy of 6.7 ± 0.8 meV and a Huang Rhys constant of 0.87 ± 0.03 at 12 K. Basal plane stacking faults are most likely formed as the coalescence process proceeds with the decomposition and crystallization processes during annealing. As shown by low-temperature monochromatic cathodoluminescence imaging, the luminescence corresponding to the 3.316 eV line is, in this second configuration, limited to some specific area ( i.e., large nanoparticles), and the relative intensity ratio of the excitonic to interface-related transitions is increased due to the smaller free surface area and density of grain boundaries.