AVS 62nd International Symposium & Exhibition
    Thin Film Thursday Sessions
       Session TF-ThP

Paper TF-ThP28
Effect of a Substrate Temperature on the Properties of the RF-sputtered Indium Selenide Thin Films as a Buffer Layer for CIGS Photovoltaics

Thursday, October 22, 2015, 6:00 pm, Room Hall 3

Session: Thin Films Poster Session
Presenter: MyoungHan Yoo, Chosun University, Republic of Korea
Authors: M.H. Yoo, Chosun University, Republic of Korea
N.H. Kim, Chosun University, Republic of Korea
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CIGS, which has suitable optical absorption, tunable band gap, good electrothermal stability, and no toxic/hazardous pollutant, has been used in thin film solar cells with the conventional structure of glass/Mo/CIGS/buffer layer/TCO. Instead of the very noxious and polluting CdS buffer layer, Cd-free materials have been attracted great interest in the buffer layer for CIGS photovoltaic applications. The Cd-free buffer layers require some qualifications, such as a band gap energy between CIGS and TCO (typically zinc oxide, Eg ~ 3.4 eV ), an optical transmittance ≥ 80%, and a resistivity ≤ 104 Ω∙cm,[1] to replace the conventional CdS buffer layer. Indium selenides are III-VI semiconducting compounds with the wide deviation from stoichiometry, which were proposed for the Cd-free buffer layer in CIGS photovoltaics with several advantages including better heterointerface of the same elemental effusion with CIGS absorber layer. In the prior studies, indium selenides were prepared by using RF-magnetron sputtering method with InSe2 target and rapid thermal annealing. The variations in film thickness, stoichiometry, annealing duration, and annealing temperature did not affect the crystallization of indium selenide precursors in amorphous nature. Subsequently, the substrate temperature, which induces significant changes in the properties of indium selenide, was varied in the RF sputtering process. Rapid thermal annealing process was performed to transform the 50-nm-thickness indium selenide into the γ-phase In2Se3 at 700oC for 1 min. Some analyses were examined in the structural, optical and electrical properties of the RF-sputtered indium selenide thin films with the different substrate temperatures for the optimal buffer layer in CIGS photovoltaics. [1] J. H. Yoon, W. M. Kim, J. K. Park, Y. J. Baik, T. Y. Seong and J. Jeong, Prog. Photovolt: Res. Appl. 22, 69 (2014).