Development of ZnO:Al-based transparent contacts deposited at low-temperature by RF-sputtering on InN layers

Authors

  • S. Fernández,

    Corresponding author
    1. Departamento de Energías Renovables, Energía Solar Fotovoltaica, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avda. Complutense 22, 28040 Madrid, Spain
    • Phone: +34 913 466 039, Fax: +34 913 466 037
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  • F. B. Naranjo,

    1. Grupo de Ingeniería Fotónica, Departamento de Electrónica, Escuela Politécnica Superior, Universidad de Alcalá Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain
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    • Phone: +34 918 856 558, Fax: +34 918 856 540

  • O. de Abril,

    1. ISOM and Departamento de Física Aplicada, Escuela Técnica Superior de Ingenieros de Telecomunicación, Universidad Politénica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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  • S. Valdueza-Felip

    1. Grupo de Ingeniería Fotónica, Departamento de Electrónica, Escuela Politécnica Superior, Universidad de Alcalá Campus Universitario, 28871 Alcalá de Henares, Madrid, Spain
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Abstract

Nitride semiconductors (Al,Ga,In)N attain material properties that make them suitable for photovoltaic and optoelectronics devices to be used in hard environments. These properties include an energy gap continuously tuneable within the energy range of the solar spectrum, a high radiation resistance and thermal stability. The developing of efficient devices requires contacts with low resistivity and high transmittance in visible region. ZnO:Al (AZO) emerges as a feasible candidate for transparent contact to nitride semiconductors, taking advantage of its low resistivity, high transparency in visible wavelengths and a very low lattice mismatch with respect to nitride semiconductors. This work presents a study of the applications of AZO films deposited at low-temperature by RF magnetron sputtering as transparent contact for InN layers. The optimization of AZO conditions deposition lead to the obtaining of contacts which shows an ohmic behaviour for the as-deposited layer, regardless the thickness of the ZnO:Al contact layer. Specific contact resistances of 1.6 Ω·cm2 were achieved for the contact with 90 nm thick ZnO:Al layer without any post-deposition treatment (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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