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

  • Rucavado E Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel CH-2002, Switzerland.
  • Graužinytė M Department of Physics, Universität Basel, Klingelbergstr. 82, 4056 Basel, Switzerland.
  • Flores-Livas JA Department of Physics, Universität Basel, Klingelbergstr. 82, 4056 Basel, Switzerland.
  • Jeangros Q Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel CH-2002, Switzerland.
  • Landucci F Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel CH-2002, Switzerland.
  • Lee Y Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720, United States.
  • Koida T Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan.
  • Goedecker S Department of Physics, Universität Basel, Klingelbergstr. 82, 4056 Basel, Switzerland.
  • Hessler-Wyser A Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel CH-2002, Switzerland.
  • Ballif C Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel CH-2002, Switzerland.
  • Morales-Masis M Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel CH-2002, Switzerland.
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  • 2018-09-28
Published in:
  • The journal of physical chemistry. C, Nanomaterials and interfaces. - 2018
General Energy
Physical and Theoretical Chemistry
Electronic, Optical and Magnetic Materials
Surfaces, Coatings and Films
English 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.
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  • English
Open access status
hybrid
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https://sonar.ch/global/documents/114627
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