New Route for ``Cold-Passivation`` of Defects in Tin-Based Oxides

Rucavado, Esteban and Grauzinyte, Migle and Flores-Livas, Jose A. and Jeangros, Quentin and Landucci, Federica and Lee, Yeonbae and Koida, Takashi and Goedecker, Stefan and Hessler-Wyser, Aicha and Ballif, Christophe and Morales-Masis, Monica. (2018) New Route for ``Cold-Passivation`` of Defects in Tin-Based Oxides. JOURNAL OF PHYSICAL CHEMISTRY C, 122 (31). pp. 17612-17620.

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Official URL: https://edoc.unibas.ch/68229/

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Transparent conductive oxides (TCOs) are essential in technologies coupling light and electricity. For Sn-based TCOs, oxygen deficiencies and undercoordinated Sn atoms result in an extended density of states below the conduction band edge. Although shallow states provide free carriers necessary for electrical conductivity, deeper states inside the band gap are detrimental to transparency. In zinc tin oxide (ZTO), the overall optoelectronic properties can be improved by defect passivation via annealing at high temperatures. Yet, the high thermal budget associated with such treatment is incompatible with many applications. Here, we demonstrate an alternative, low-temperature passivation method, which relies on cosputtering Sn-based TCOs with silicon dioxide (SiO2). Using amorphous ZTO and amorphous/polycrystalline tin dioxide (SnO2) as representative cases, we demonstrate through optoelectronic characterization and density functional theory simulations that the SiO2 contribution is twofold. First, oxygen from SiO2 passivates the oxygen deficiencies that form deep defects in SnO2 and ZTO. Second, the ionization energy of the remaining deep defect centers is lowered by the presence of silicon atoms. Remarkably, we find that these ionized states do not contribute to sub-gap absorptance. This simple passivation scheme significantly improves the optical properties without affecting the electrical conductivity, hence overcoming the known transparency–conductivity trade-off in Sn-based TCOs.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Physik (Goedecker)
UniBasel Contributors:Goedecker, Stefan
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:16 Oct 2019 15:00
Deposited On:08 Oct 2019 07:32

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