Interpretation of the effect of back surface etching on barrier height, carriers concentration and defects density of the CdTe solar cell devices

ORAL

Abstract

Thin film CdS/CdTe photovoltaic devices have shown a potential interest by the researchers due to the low fabrication cost and high device stability. Developing an appropriate back contact for CdTe solar cells is crucial to achieve good device performance. In this work, we explore the impacts of hydrogen iodide acid etching on the back surface of CdTe solar cell devices to remove the back oxides and chlorides formed during CdCl2 treatment and form a Te-rich back surface. The back barrier height, carrier density and defect states are measured by temperature dependence of current-voltage (J-V-T), capacitance-voltage (C-V-T), admittance spectroscopy (AS) and impedance spectroscopy (IS) measurements. In C-V measurements, an appropriate AC modulation voltage and frequency will be selected, and DC bias voltage will be scanned. In AS and IS measurements, carriers or defects emission induces by applying small AC modulation voltage to be trapped and detrapped at certain frequencies and temperatures. An obvious increase in carrier concentration, suggesting an increased copper doping in the device. Additionally, the HI-treatment eliminates another defect level at 0.41 eV with respect to the valance band. All these improvements lead to better device performance of CdTe solar cells.

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Presenters

  • Rasha A. Awni

    Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.

Authors

  • Rasha A. Awni

    Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.

  • Deng-Bing Li

    University of Toledo, Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.

  • Corey R. Grice

    Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.

  • Zhaoning Song

    Univ of Toledo, Wright Ctr for Photovoltaics Innovation and Commercialization, Sch. for Solar and Adv. Energy, Dept of Physics and Astronomy, Univ of Toledo, Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.

  • Randy J. Ellingson

    Wright Ctr for Photovoltaics Innovation and Commercialization, Sch. for Solar and Adv. Energy, Dept of Physics and Astronomy, Univ of Toledo, Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.

  • Michael J. Heben

    The University of Toledo, Wright Center for Photovoltaics Innovation and Commercialization, Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA, Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA., Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Department of Physics and Astronomy, Toledo, Ohio, 43606, USA

  • Jian V. V. Li

    Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 70101, Taiwan, and Department of Physics, and Material Science, Engineering, and Commercial

  • Yanfa Yan

    The University of Toledo, Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Wright Ctr for Photovoltaics Innovation and Commercialization, Sch. for Solar and Adv. Energy, Dept of Physics and Astronomy, Univ of Toledo, Department of Physics and Astronomy, The Wright Center for Photovoltaics Innovation and Commercialization (PVIC), University of Toledo, Toledo OH 43606, USA.