Hostname: page-component-8448b6f56d-42gr6 Total loading time: 0 Render date: 2024-04-20T14:48:05.867Z Has data issue: false hasContentIssue false
  • English
  • Français

Diffusion Behavior and Microstructural Properties of the CBD-ZnS/CIGS Interface Boundary

Published online by Cambridge University Press:  21 March 2011

Tokio Nakada
Tokio Nakada*
Affiliation:
Department of Electrical Engineering and electronics, Aoyama Gakuin University Setagaya-ku, Tokyo 157-8572, Japan
Get access

Abstract

The diffusion behavior and microstructural properties of the CBD-ZnS/Cu(In,Ga)Se2 (CIGS) interface of high-efficiency Cd-free CIGS thin film solar cells with efficiencies exceeding 17 % have been investigated using energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). CBD-ZnS thin layers are found to grow with small polycrystalline grains that consist of sphalerite and wurtzite phases. This is in sharp contrast to CBD-CdS layers which grow epitaxially on CIGS grains. Micro-EDX analysis revealed Zn indiffusion into the CIGS thin layer a distance of approximately 40 nm from the CBD-ZnS/CIGS interface boundary after air-annealing at 200°C, whereas no diffusion of Zn was observed before annealing. These results suggest that the main role of the air-annealing process is not substitution of Se vacancies by oxygen atoms but the diffusion of Zn into CIGS which may result in the formation of a pn homojunction. On the other hand, negligible Zn-diffusion into a CuGaSe2 thin film was found at the CBD-ZnS/CuGaSe2 interface boundary even after air-annealing. The cell performance of CBD-ZnS/CIGS thin film solar cells is discussed in connection with the Ga/(In+Ga) atomic ratio, conduction band-offset and Zn-diffusion.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 668: Symposium H – II-IV Compound Semiconductor Photovoltaic Materials , 2001 , H7.1
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Ramanathan, K., Wiesner, H., Asher, S., Nieles, D., Bhattacharya, R. N., Keane, J., Contreras, M. A., and Noufi, R.: Proc. 2nd WCPEC (1998) pp.477–481.Google Scholar
2. Wada, T., Hayashi, S., Hashimoto, Y., Nishiwaki, S., Sato, T., Negami, T. and M. Nishitani: Proc. 2nd WCPEC (1998) pp.403–408.Google Scholar
3. Nakada, T. and Kunioka, A.: Appl. Phys. Lett. Vol.74 No.12, 2444–2446 (1999).Google Scholar
4. Nakada, T., Kume, T., Mise, T., and Kunioka, A.: Jpn. J. Appl. Phys. Vol. 37, L499–L501 (1998).Google Scholar
5. Yamamoto, T.: Private communication.Google Scholar
6. Nakada, T. and M. Mizutani: Proc. 28th IEEE Photovoltaic Specialists Conf., (2000, Anchorage)529–534.Google Scholar
7. JCPDS Powder Diffraction File Card No. 23–209, Joint Committee on Powder Diffraction Standards, Swarthmore, PA, (1984).Google Scholar
8. JCPDS Powder Diffraction File Card No. 35–1100, Joint Committee on Powder Diffraction Standards, Swarthmore, PA, (1984).Google Scholar
9. Tell, B., Wagner, Sigurd, and Bridenbaugh, P.M.: Appl. Phys. Lett. Vol. 28, No. 8 (1976) 454–455.Google Scholar
10. Tell, B. and Bridenbaugh, P. M.: J. Appl. Phys. Vol. 48, No. 6 (1977) 2477–2480.Google Scholar
11. Sugiyama, T., Chaisitsak, S., Yamada, A., Konagai, M., Kudriavtsev, Y., Godines, A., Villegas, A. and Asomaza, R.: Jpn. J. Appl. Phys. Vol. 39 (2000)4816–4819.Google Scholar