Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014)
    Energy Harvesting & Storage Tuesday Sessions
       Session EH-TuP

Paper EH-TuP16
Effect of MoN Diffusion Barrier on High Temperature Selenization of Cu(In,Ga)

Tuesday, December 9, 2014, 4:00 pm, Room Mauka

Session: Energy Harvesting & Storage Poster Session
Presenter: Min-Su Kwon, Yeungnam University, Republic of Korea
Authors: M.-S. Kwon, Yeungnam University, Republic of Korea
H.-G. Kim, Yeungnam University, Republic of Korea
S.-H. Kim, Yeungnam University, Republic of Korea
C.-W. Jeon, Yeungnam University, Republic of Korea
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In commercial manufacturing of CIGS photovoltaic module, the absorber films are usually produced by sputtering and selenization/sulfurization process. During high temperature selenization above 450 ℃, the surface of Mo back contact is easily transformed to MoSe2, which is beneficial for ohmic contact formation in Mo/CIGS interface.[1] Although MoSe2 has a high resistance, because it is a semiconductor of having bandgap energy of 1.35~1.41 eV, the thin layer of 100nm or less does not adversely affect the characteristics of solar cell.[2] However, since MoSe2 may provide a current blocking capability when thicker than 200nm, it is necessary to control the thickness of the MoSe2. In this study, Mo/MoxN/Mo multi-layer back contact was selenized to evaluate capability of diffusion barrier of MoxN layer to prevent the excessive MoSe2 formation. The CIGS absorber films were obtained by solid state selenization, where a sputtered CuInGa alloy film on Mo/MoxN/Mo/glass was subsequently selenizated at 460~560 ℃ for 10 minutes by using Se vapor. Behavior of generated MoSe2 was analyzed by using XRD, SEM. The conducting compound of MoxN as a diffusion barrier against Se was deposited by a reactive sputtering. The thickness and N content of MoxN was found to be linearly proportional to N2 gas flow rate, which suggests that MoxN could be easily adjusted by a simple modification of Mo formation process. As a result of selenization, because of the formation of MoSe2, thickness of Mo mono-layer precursor was abruptly increased. But the thickness of multi-layered back contact with MoxN was not changed significantly. Therefore, as a diffusion barrier, MoxN was confirmed to be excellent diffusion barrier that is suited for a high temperature selenization process. The effect of MoxN layer on solar cell performance will be discussed. Acknowledgements This research was financially supported by the Ministry of Knowledge Economy(MKE), Korea Institute for Advancement of Technology(KIAT) and Dae-Gyeong Leading Industry Office through the Leading Industry Development for Economic Region). References [1] P.J. Rostan*, J.Mattheis, G.Bilger, U. Rau, J.H. Werner, Thin Solid Films Volume 480-481, Pages 67-70(2005). [2] SeJin Ahn, Ki hyun Kim, Jae Ho Yun, and Kyung Hoon Yoon, Journal of Applied Physics 105, 113533(2009)