Mapping the Electrical Properties of ZnO-Based Transparent Conductive Oxides Grown at Room Temperature and Improved by Controlled Postdeposition Annealing

Andriy Lyubchyk, António Vicente, Bertrand Soule, Pedro Urbano Alves, Tiago Mateus, Manuel J. Mendes, Hugo Águas, Elvira Fortunato, Rodrigo Martins

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32 Citations (Scopus)

Abstract

Indium tin oxide (ITO) is the current standard state-of-the-art transparent conductive oxide (TCO), given its remarkable optical and electrical properties. However, the scarcity of indium carries an important drawback for the long-term application due to its intensive use in many optoelectronic devices such as displays, solar cells, and interactive systems. Zinc oxide-based TCOs can be a cost-effective and viable alternative, but the limitations imposed by their transmittance versus resistivity tradeoff still keep them behind ITO. In this work, an in-depth study of the structural and compositional material changes induced by specific postannealing treatments is presented, based on aluminum zinc oxide (AZO) and hydrogenated AZO (AZO:H) thin films grown by rf-magnetron sputtering at room temperature that allows an extensive understanding of the films' electrical/structural changes and the ability to tune their physical parameters to yield increasingly better performances, which put them in line with the best ITO quality standards. The present investigation comprises results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres and plasmas. Overall the study being performed leads to a decrease in resistivity above 40%, reaching ρ ≈ 3 × 10−4 Ω cm, with an average optical transmittance in the visible region around 88%. Such results are equivalent to the properties of state-of-the-art ITO.

Original languageEnglish
Article number1500287
JournalAdvanced Electronic Materials
Volume2
Issue number1
DOIs
Publication statusPublished - 1 Jan 2016

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Zinc Oxide
Indium
Oxides
Electric properties
Tin oxides
Annealing
Zinc oxide
Aluminum
Temperature
Opacity
Optoelectronic devices
Magnetron sputtering
Atmospheric pressure
Oxide films
Solar cells
Optical properties
Gases
Display devices
Vacuum
Plasmas

Keywords

  • aluminum zinc oxide
  • annealing maps
  • electrical properties
  • thin films

Cite this

@article{e24c65297e7a4eaeb87d284e6c628315,
title = "Mapping the Electrical Properties of ZnO-Based Transparent Conductive Oxides Grown at Room Temperature and Improved by Controlled Postdeposition Annealing",
abstract = "Indium tin oxide (ITO) is the current standard state-of-the-art transparent conductive oxide (TCO), given its remarkable optical and electrical properties. However, the scarcity of indium carries an important drawback for the long-term application due to its intensive use in many optoelectronic devices such as displays, solar cells, and interactive systems. Zinc oxide-based TCOs can be a cost-effective and viable alternative, but the limitations imposed by their transmittance versus resistivity tradeoff still keep them behind ITO. In this work, an in-depth study of the structural and compositional material changes induced by specific postannealing treatments is presented, based on aluminum zinc oxide (AZO) and hydrogenated AZO (AZO:H) thin films grown by rf-magnetron sputtering at room temperature that allows an extensive understanding of the films' electrical/structural changes and the ability to tune their physical parameters to yield increasingly better performances, which put them in line with the best ITO quality standards. The present investigation comprises results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres and plasmas. Overall the study being performed leads to a decrease in resistivity above 40{\%}, reaching ρ ≈ 3 × 10−4 Ω cm, with an average optical transmittance in the visible region around 88{\%}. Such results are equivalent to the properties of state-of-the-art ITO.",
keywords = "aluminum zinc oxide, annealing maps, electrical properties, thin films",
author = "Andriy Lyubchyk and Ant{\'o}nio Vicente and Bertrand Soule and Alves, {Pedro Urbano} and Tiago Mateus and Mendes, {Manuel J.} and Hugo {\'A}guas and Elvira Fortunato and Rodrigo Martins",
note = "A.L. and A.V. contributed equally to this work. This work was supported by the Fundacao para a Ciencia e a Tecnologia (FCT) through the projects EXCL/CTM-NAN/0201/2012, PEst-C/CTM/LA0025/2013-14, and PTDC/CTM-ENE/2514/2012; as well as by the European projects CEOPS (FP7 Grant No. 309984), i-Flexis (FP7-ICT Grant No. 611070), and All-Oxide-Photovoltaics (FP7-FET Grant No. 309018). A. Vicente acknowledges support from FCT and MIT-Portugal through the scholarship SFRH/BD/33978/2009. M. J. Mendes acknowledges funding by the EU Marie Curie Action FP7-PEOPLE-2013-IEF through the DIELECTRIC PV project (Grant No. 629370). Authors also acknowledge A. Araujo and J. Pinto for fruitful discussions and for carrying out the XRD measurements and L. Pereira for revising the manuscript.",
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doi = "10.1002/aelm.201500287",
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T1 - Mapping the Electrical Properties of ZnO-Based Transparent Conductive Oxides Grown at Room Temperature and Improved by Controlled Postdeposition Annealing

AU - Lyubchyk, Andriy

AU - Vicente, António

AU - Soule, Bertrand

AU - Alves, Pedro Urbano

AU - Mateus, Tiago

AU - Mendes, Manuel J.

AU - Águas, Hugo

AU - Fortunato, Elvira

AU - Martins, Rodrigo

N1 - A.L. and A.V. contributed equally to this work. This work was supported by the Fundacao para a Ciencia e a Tecnologia (FCT) through the projects EXCL/CTM-NAN/0201/2012, PEst-C/CTM/LA0025/2013-14, and PTDC/CTM-ENE/2514/2012; as well as by the European projects CEOPS (FP7 Grant No. 309984), i-Flexis (FP7-ICT Grant No. 611070), and All-Oxide-Photovoltaics (FP7-FET Grant No. 309018). A. Vicente acknowledges support from FCT and MIT-Portugal through the scholarship SFRH/BD/33978/2009. M. J. Mendes acknowledges funding by the EU Marie Curie Action FP7-PEOPLE-2013-IEF through the DIELECTRIC PV project (Grant No. 629370). Authors also acknowledge A. Araujo and J. Pinto for fruitful discussions and for carrying out the XRD measurements and L. Pereira for revising the manuscript.

PY - 2016/1/1

Y1 - 2016/1/1

N2 - Indium tin oxide (ITO) is the current standard state-of-the-art transparent conductive oxide (TCO), given its remarkable optical and electrical properties. However, the scarcity of indium carries an important drawback for the long-term application due to its intensive use in many optoelectronic devices such as displays, solar cells, and interactive systems. Zinc oxide-based TCOs can be a cost-effective and viable alternative, but the limitations imposed by their transmittance versus resistivity tradeoff still keep them behind ITO. In this work, an in-depth study of the structural and compositional material changes induced by specific postannealing treatments is presented, based on aluminum zinc oxide (AZO) and hydrogenated AZO (AZO:H) thin films grown by rf-magnetron sputtering at room temperature that allows an extensive understanding of the films' electrical/structural changes and the ability to tune their physical parameters to yield increasingly better performances, which put them in line with the best ITO quality standards. The present investigation comprises results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres and plasmas. Overall the study being performed leads to a decrease in resistivity above 40%, reaching ρ ≈ 3 × 10−4 Ω cm, with an average optical transmittance in the visible region around 88%. Such results are equivalent to the properties of state-of-the-art ITO.

AB - Indium tin oxide (ITO) is the current standard state-of-the-art transparent conductive oxide (TCO), given its remarkable optical and electrical properties. However, the scarcity of indium carries an important drawback for the long-term application due to its intensive use in many optoelectronic devices such as displays, solar cells, and interactive systems. Zinc oxide-based TCOs can be a cost-effective and viable alternative, but the limitations imposed by their transmittance versus resistivity tradeoff still keep them behind ITO. In this work, an in-depth study of the structural and compositional material changes induced by specific postannealing treatments is presented, based on aluminum zinc oxide (AZO) and hydrogenated AZO (AZO:H) thin films grown by rf-magnetron sputtering at room temperature that allows an extensive understanding of the films' electrical/structural changes and the ability to tune their physical parameters to yield increasingly better performances, which put them in line with the best ITO quality standards. The present investigation comprises results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres and plasmas. Overall the study being performed leads to a decrease in resistivity above 40%, reaching ρ ≈ 3 × 10−4 Ω cm, with an average optical transmittance in the visible region around 88%. Such results are equivalent to the properties of state-of-the-art ITO.

KW - aluminum zinc oxide

KW - annealing maps

KW - electrical properties

KW - thin films

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