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New Route for "Cold-Passivation" of Defects in Tin-Based Oxides
Esteban Rucavado1, Miglė Graužinytė2, José A Flores-Livas2
1Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel CH-2002, Switzerland.
The Journal of Physical Chemistry. C, Nanomaterials and Interfaces
|September 28, 2018
Summary
Silicon dioxide (SiO2) cosputtering offers a low-temperature method to improve transparent conductive oxides (TCOs). This technique enhances optical properties of tin-based TCOs without compromising electrical conductivity.
Area of Science:
- Materials Science
- Solid State Physics
- Optoelectronics
Background:
- Transparent conductive oxides (TCOs) are critical for optoelectronic devices.
- Sn-based TCOs suffer from defects caused by oxygen deficiencies and undercoordinated Sn atoms, impacting transparency.
- High-temperature annealing is a conventional but often impractical method for defect passivation in zinc tin oxide (ZTO).
Purpose of the Study:
- To develop a low-temperature defect passivation method for Sn-based TCOs.
- To investigate the role of silicon dioxide (SiO2) in improving optoelectronic properties.
- To overcome the transparency-conductivity trade-off in transparent conductive oxides.
Main Methods:
- Cosputtering of Sn-based TCOs with silicon dioxide (SiO2).
- Optoelectronic characterization of amorphous ZTO and amorphous/polycrystalline SnO2.
- Density functional theory (DFT) simulations to understand defect passivation mechanisms.
Main Results:
- SiO2 passivates oxygen deficiencies, reducing deep defects in SnO2 and ZTO.
- Silicon atoms lower the ionization energy of remaining deep defect centers.
- Ionized defect states do not contribute to sub-gap absorptance, improving transparency.
- Optical properties are significantly enhanced without affecting electrical conductivity.
Conclusions:
- Low-temperature SiO2 cosputtering is an effective passivation strategy for Sn-based TCOs.
- This method successfully addresses the transparency-conductivity trade-off.
- The findings offer a practical alternative to high-temperature annealing for TCO applications.