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Band Alignment at CdS/wide-band-gap Cu(In,Ga)Se2 Hetero-junction by using PES/IPES

  • Kong, Sok-Hyun (HDD program Team, Material & Devices Research Center, Samsung Advanced Institute of Technology) ;
  • Kima, Kyung-Hwan (Department of Electrical Information Engineering, KyungWon University)
  • 발행 : 2005.10.01

초록

Direct characterization of band alignment at chemical bath deposition $(CBD)-CdS/Cu_{0.93}(In_{1-x}Ga_x)Se_2$ has been carried out by photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). Ar ion beam etching at the condition of the low ion kinetic energy of 400 eV yields a removal of surface contamination as well as successful development of intrinsic feature of each layer and the interfaces. Especially interior regions of the wide gap CIGS layers with a band gap of $1.4\~1.6\;eV$ were successfully exposed. IPES spectra revealed that conduction band offset (CBO) at the interface region over the wide gap CIGS of x = 0.60 and 0.75 was negative, where the conduction band minimum of CdS was lower than that of CIGS. It was also observed that an energy spacing between conduction band minimum (CBM) of CdS layer and valance band maximum (VBM) of $Cu_{0.93}(In_{0.25}Ga_{0.75})Se_2$ layer at interface region was no wider than that of the interface over the $Cu_{0.93}(In_{0.60}Ga_{0.40})Se_2$ layer.

키워드

참고문헌

  1. G. Voorwinden, R. Kiese, and M. Powalla, 'In-line Cu(In,Ga)$Se_2$ co-evaporation processes with graded band gaps on large substrates', Thin Solid Films, Vol. 431-432, p. 538, 2003 https://doi.org/10.1016/S0040-6090(03)00258-X
  2. M. A. Contreras, J. Tuttle, A. Gabor, A. Tennant, K. Ramanathan, S. Asher, A. Franz, J. Keane, L. Wang, and R. Noufi, 'High efficiency graded bandgap thin-film polycrystalline Cu(In,Ga) $Se_2$-based solar cells', Sol. Energy Mater. Sol. Cells, Vol. 41/42, p. 231, 1996
  3. T. Minemoto, Y. Hashimoto, W. S. Kolahi, T. Satoh, T. Negmi, H. Takakura, and Y. Hamakawa, 'Control of conduction band offset in wide-gap Cu(In,Ga)$Se_2$ solar cells', Sol. Energy Mater. Sol. Cell, Vol. 75, p. 121, 2003
  4. R. Herberholz, V. Nadenau, U. Ruhle, C. Koble, H. W. Schock, and B. Dimmeler, 'Prospects of wide-gap chalcopyrites for thin film photovoltaic modules', Sol. Energy Mater. Sol. Cell, Vol. 49, p. 227, 1997
  5. T. Minemoto, Y. Hashimoto, T. Satoh, T. Negami, H. Takakura, and Y. Hamakawa, 'Cu(In,Ga)Se[sub2] solar cells with controlled conduction band offset of window/Cu(In,Ga)Se[sub2] layers', J. Apply. Phys., Vol. 89, p. 8327, 2001 https://doi.org/10.1063/1.1339859
  6. D. Schmid, M. Ruckh, and H. W. Schock, 'A comprehensive characterization of the interfaces in Mo/CIS/CdS/ZnO solar cell structures', Sol. Energy Mater. Sol. Cell, Vol. 41-42, p. 281,1996 https://doi.org/10.1016/0927-0248(95)00107-7
  7. T. Schulmeyer, R. Hunger, A. Klein, W. Jaegermann, and S. Niki, 'Photoemission study and band alignment of the CuInSe[sub2](001)/CdS heterojunction', Appl. Phys. Lett, Vol. 84, p. 3067, 2004
  8. L. Kronik, L. Burstein, M. Leibovitch, Y. Shapira, D. Gal, E. Moons, J. Beier, G. Hodes, D. Cahen, D. Hariskos, R. Klenk, and H. W. Schock, 'Band diagram of the polycrystalline CdS/Cu(In,Ga) Se[sub2] heterojunction', Appl. Phys. Lett., Vol. 67, p. 1405, 1995
  9. M. Morkel, L. Weinhardt, R. Lohmuller, C. Heske, E. Umbach, W. Riedl, S. Zweigart, and F. Karg, 'Flat conduction-band alignment at the CdS/CuInSe[sub2] thin-film solar-cell heterojunction', Appl. Phys. Lett., Vol. 79, p. 4482, 2001.
  10. N. Terada, R. T. Widodo, K. Itoh, S. H. Kong, H. Kashiwabara, T. Okuda, K. Obara, S. Niki, K. Sakurai, A. Yamada, and S. Ishizuka, 'Characterization of interface nature and band alignment in CBD-CdS/Cu(In,Ga)$Se_2$bi-layer structure by photoemission and inverse photoemission spectroscopy', Thin Solid Films, Vol. 480-481, p. 183, 2005
  11. B. Canava, J. Vigneron, A. Etcheberry, D. Guimard, P. P. Grand, J.-F. Guillemoles, D. Licot, S. Ould Saad Hamatly, Z. Djebbour, and D. Mencaraglia, 'Studies of buried interfaces Cu(In,Ga)$Se_2$/CdS XPS and electrical investigations', Thin Solid Films, Vol.431-432, p. 289, 2003 https://doi.org/10.1016/S0040-6090(03)00273-6
  12. G. K. Padam, G. Malhotra, and S. K. Gupta, 'Study of intrinsic defects in vacuum/air annealed $CuInSe_2$', Solar Energy Materials, Vol. 22, p. 303, 1991
  13. D. Cahen and R. Noufi, 'Surface passivation of polycrystalline, chalcogenide based photovoltaic cells', Solar Cells, Vol. 30, p. 53, 1991
  14. I. Dirnstorfer, W. Burkhardt, W. Kriegseis, I. Osterreicher, H. Alves, D. M. Hofmann, O. Ka, A. Polity, B. K. Meyer, and D. Braunger, 'Annealing studies on CuIn(Ga)$Se_2$: the influence of gallium', Thin Solid Films, Vol.361-362, p. 400, 2000