Abstract
Recently the authors have demonstrated that compensated or “midgap” intrinsic hydrogenated microcrystalline silicon (μc-Si:H), as deposited by the Very High Frequency Glow Discharge (VHF-GD) technique, can be used as active layer in p-i-n solar cells. Compared to amorphous silicon (a-Si:H), μc-Si:H was found to have a significantly lower energy bandgap ofaround 1 eV. The combination of both materials (two absorbers with different gap energies) leads to a “real” tandem cell structure, which was called the “micromorph” cell. Micromorph cells can make better use of the sun's spectrum in contrast to conventional double-stacked a-Si:H / a-Si:H tandems.
The present study will show that the compensation technique (involving boron “microdoping”) used sofar for obtaining midgap μc-Si:H can be replaced by the application of a gas purifier. The use of this gas purifier has a beneficial influence on the transport properties of undoped intrinsic μc-Si:H. By this procedure, increased cell efficiencies in both, single microcrystalline silicon p-i-n as well as micromorph cells could be obtained. In the first case 7.7 % stable, and in the second case 13.1% initial efficiency could be achieved under AMI.5 conditions. Preliminary light-soaking experiments performed on the tandem cells indicate that microcrystalline silicon could contribute to an enhancement of the stable efficiency performance. Micromorph cell manufacturing is fully compatible to a-Si:H technology; however, its deposition rate is still too low. With further increase of the rate, a similar cost reduction potential like in a-Si:H technology can be extrapolated.
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References
H. Curtins, N. Wyrsch, A. Shah, Electron. Lett. 23, (1987), p. 228.
R. Flückiger, J. Meier, H. Keppner, M. Götz, A. Shah, Proc. 23rd IEEE PVSC (1993), p. 839.
H. Keppner, U. Kroll, J. Meier, A. Shah, Solid State Phenomena 44–46, (1995), pp. 97–126.
F. Finger, P. Hapke, M. Luysberg, R. Carius, H. Wagner, Appl. Phys. Lett. 65, (1994), p. 2588.
R. Flückiger, J. Meier, G. Crovini, F. Demichelis, F. Giorgis, C. F. Pirri, E. Tresso, J. Pohl, V. Rigato, S. Zandolin, F. Caccavale, Mat. Res. Soc. Symp. Proc. 358, (1995), p. 751.
S. Grebner, F. Wang, and R. Schwarz, Mat. Res. Soc. Symp. Proc. 283, (1992), p.513.
F. Wang, H.N. Liu, Y.L. He, A. Schweiger, R. Schwarz, J. Non-Cryst. Solids 137&138, (1991), p. 511.
G. Willeke, thesis (1983), Univ. of Dundee.
C. Wang, G. Lucowsky, 21th IEEE (1990), p. 1614; and M.J. Williams, C. Wang, G. Lucovsky, J. Non-Cryst. Solids 137&138, (1991), p. 737.
P. Torres, H. Keppner, R. Flückiger, J. Meier, A. Shah, H. Kiess, Proc. 12th EC PVSEC (1994), p. 705.
H. Keppner, P. Torres, R. Flückiger, J. Meier, A. Shah, C. Fortmann, P. Fath, G. Willeke, K. Happle, H. Kiess, Solar Energy Materials and Solar Cells 34, (1994), p. 201.
R. Flückiger, J. Meier, M. Goetz, A. Shah, J. Appl. Phys. 77, (1995), p. 712.
J. Meier, R. Flückiger, H. Keppner, A. Shah, Appl. Phys. Lett. 65, (1994), p. 860.
J. Meier, S. Dubail, R. Flückiger, D. Fischer, H. Keppner, A. Shah, Proc. 1st WCPEC (1994), p. 409.
J. Meier, R. Flückiger, H. Keppner, M. Götz, A. Shah, Proc. 12th EC PVSEC (1994), p. 1237.
J. Meier, S. Dubail, J.A. Anna Selvan, N. Pellaton Vaucher, R. Platz, C. Hof, R. Flückiger, U. Kroll, N. Wyrsch, P. Torres, H. Keppner, A. Shah, K.D. Ufert, Proc. 13th Europ., (Nice 1995), p. 1445.
N. Beck, J. Meier, J. Fric, Z. Remes, A. Poruba, R. Fliickiger, J. Pohl, A. Shah, M. Vanecek, 16th ICAS (Kobe 1995), to be published in J. Non-Cryst. Solids.
M.A. Green, M. J. Keevers, Progress in Photovoltaics: Research and Applications 3, (1995), p. 189.
R. Flückiger, J. Meier, A. Shah, A. Catana, M. Brunei, H.V. Nguyen, R.W. Collins, R. Carius, Mat. Res. Soc. Symp. Proc. 336, (1994), p. 511.
U. Kroll, J. Meier, H. Keppner, A. Shah, S.D. Littlewood, I.E. Kelly, P. Giannoulès, J. Vac. Sci. Technol. A 13, (1995), p. 2742.
U. Kroll, J. Meier, H. Keppner, A. Shah, S.D. Littlewood, I.E. Kelly, P. Giannoulès, Mat. Res. Soc. Symp. Proc. 377, (1995), p. 39.
J.A. Anna Selvan, H. Keppner, M. Götz, A. Shah, this conference.
P. van den Berg, H. Calwer, P. Marklsdorfer, R. Meckes, F. W. Schulze, K.-D. Ufert, H. Vogt, Solar Energy Materials and Solar Cells 31, (1993), p. 253.
R. Platz, D. Fischer, C. Hof, S. Dubail, U. Kroll, J. Meier, A. Shah, this conference.
D. Fischer, A. Shah, Appl. Phys. Lett. 65, (1994), p. 986.
P. Torres et al., to be submitted to Appl. Phys. Lett.
M.H. Brodsky, M. Cardona, J.J. Cuomo, Phys. Rev. B 16, (1977), p. 3556.
G. Lucovsky, R.J. Nemanich, J.C. Knights, Phys. Rev. B 19, (1979), p. 2064.
H. Wagner, W. Beyer, Solid State Commun. 48, (1983), p. 587.
Y.J. Chabal, E.E. Chaban, S.B. Christman, J. Electron Spectr. and Rel. Phenom. 29, (1983), p. 35.
Y.J. Chabal, Phys. Rev. Lett. 50, (1983), p. 1850.
T. Satoh, A. Hiraki, Jpn. J. Appl. Phys. 24, (1985), p. L491.
U. Kroll, J. Meier, A. Shah, S. Mikhailov, J. Weber, submitted to J. Appl. Phys.
F. Finger, K. Prasad, S. Dubail, A. Shah, X.-M. Tang, J. Weber, W. Beyer, Mat. Res. Soc. Symp. Proc. 219, (1991), p. 383.
N. Wyrsch, M. Goerlitzer, N. Beck, J. Meier, A. Shah, this conference.
T. Baba, T. Matsuyama, S. Tsuge, K. Wakisaka, S. Tsuda, Proc. 13th Europ. PVSEC, (Nice 1995), p. 1708.
J. Yang, X. Xu, S. Guha, Mat. Res. Soc. Symp. Proc. 336, (1994), p. 687.
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This work was supported by Swiss Federal Research Grant EF-REN (93)032.
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Meier, J., Torres, P., Platz, R. et al. On the Way Towards High Efficiency Thin Film Silicon Solar Cells by the “Micromorph” Concept. MRS Online Proceedings Library 420, 3–14 (1996). https://doi.org/10.1557/PROC-420-3
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DOI: https://doi.org/10.1557/PROC-420-3