Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-13T06:48:22.619Z Has data issue: false hasContentIssue false

Study of Band Alignment at CBD-CdS/Cu(In1-xGax)Se2 (x = 0.2 - 1.0) Interfaces by Photoemission and Inverse Photoemission Spectroscopy

Published online by Cambridge University Press:  01 February 2011

Shimpei Teshima
Affiliation:
bt202049@ms.kagoshima-u.ac.jp, Kagoshima University, Nano-structure and Advanced Materials, 1-21-40, Korimoto, Kagoshima, 890-0065, Japan
Hirotake Kashiwabara
Affiliation:
ee01016@h13.eee.kagoshima-u.ac.jp, Kagoshima University, Nano-structure and Advanced Materials, 1-21-40, Korimoto, Kagoshima, 890-0065, Japan
Keimei Masamoto
Affiliation:
bt202075@ms.kagoshima-u.ac.jp, Kagoshima University, Nano-structure and Advanced Materials, 1-21-40, Korimoto, Kagoshima, 890-0065, Japan
Kazuya Kikunaga
Affiliation:
ee01023@h13.eee.kagoshima-u.ac.jp, Kagoshima University, Nano-structure and Advanced Materials, 1-21-40, Korimoto, Kagoshima, 890-0065, Japan
Kazunori Takeshita
Affiliation:
bt202049@ms.kagoshima-u.ac.jp, Kagoshima University, Nano-structure and Advanced Materials, 1-21-40, Korimoto, Kagoshima, 890-0065, Japan
Tetsuji Okuda
Affiliation:
okuda@eee.kagoshima-u.ac.jp, Kagoshima University, Nano-structure and Advanced Materials, 1-21-40, Korimoto, Kagoshima, 890-0065, Japan
Keiichiro Sakurai
Affiliation:
k-sakurai@aist.go.jp, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, 1-1-1, Umezono, Tsukuba, 305-8568, Japan
Shogo Ishizuka
Affiliation:
shogo-ishizuka@aist.go.jp, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, 1-1-1, Umezono, Tsukuba, 305-8568, Japan
Akimasa Yamada
Affiliation:
a.yamada@aist.go.jp, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, 1-1-1, Umezono, Tsukuba, 305-8568, Japan
Koji Matsubara
Affiliation:
koji.matsubara@aist.go.jp, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, 1-1-1, Umezono, Tsukuba, 305-8568, Japan
Shigeru Niki
Affiliation:
shigeru-niki@aist.go.jp, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, 1-1-1, Umezono, Tsukuba, 305-8568, Japan
Yukio Yoshimura
Affiliation:
yosiyuki@kagoshima-it.go.jp, Kagoshima Prefectural Institute of Industrial Technology, 1445-1, Oda, Hayato, Kirishima, 899-5105, Japan
Norio Terada
Affiliation:
terada@eee.kagoshima-u.ac.jp, Kagoshima University, Nano-structure and Advanced Materials, 1-21-40, Korimoto, Kagoshima, 890-0065, Japan
Get access

Abstract

Dependence of band alignments at interfaces between CdS by chemical bath deposition and Cu(In1-xGax)Se2 by conventional 3-stage co-evaporation on Ga substitution ratio x from 0.2 to 1.0 has been systematically studied by means of photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). For the specimens of the In-rich CIGS, conduction band minimum (CBM) by CIGS was lower than that of CdS. Conduction band offset of them was positive about +0.3 ~ +0.4 eV. Almost flat conduction band alignment was realized at x = 0.4 ~ 0.5. On the other hand, at the interfaces over the Ga-rich CIGS, CBM of CIGS was higher than that of CdS, and CBO became negative. The present study reveals that the decrease of CBO with a rise of x presents over the wide rage of x, which results in the sign change of CBO around 0.4 ~ 0.45. In the Ga-rich interfaces, the minimum of band gap energy, which corresponded to energy spacing between CBM of CdS and valence band maximum of CIGS, was almost identical against the change of band gap energy of CIGS. Additionally, local accumulation of oxygen related impurities was observed at the Ga-rich samples, which might cause the local rise of band edges in central region of the interface.

Type
Research Article
Copyright
Copyright © Materials Research Society 2007

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

1. Voorwinden, G., Kniese, R. and Powalla, M., Thin Solid Films 431-432, 538 (2003).Google Scholar
2. Contreras, M. A., Tuttle, J., Gabor, A., Tennant, A., Ramanathan, K., Asher, S., Franz, A., Keane, J., Wang, L. and Noufi, R., Sol. Energy Mater. Sol. Cells 41/42, 231 (1996).Google Scholar
3. Minemoto, T., Hashimoto, Y., Kolahi, W. S., Satoh, T., Negami, T., Takakura, H. and Hamakawa, Y., Sol. Energy Mater. Sol. Cells 75, 121 (2003).Google Scholar
4. Ramanathan, K., Contreras, M. A., Perkins, C. L., Asher, S., Hasoon, F. S., Keane, J., Young, D., Romero, M., Metzger, W., Ward, J. and Duda, A., Prog. Photovoltaics. Res. Appl. 11, 225 (2003).Google Scholar
5. Siebentritt, S., Thin Solid Films 403-404, 1 (2002).Google Scholar
6. Černivec, G., Krč, J., Smole, F. and Topič, M., Thin Solid Films 511-512, 60 (2006).Google Scholar
7. Minemoto, T., Hashimoto, Y., Satoh, T., Negami, T., Takakura, H. and Hamakawa, Y., J.Appl. Phys. 89, 8327 (2001).Google Scholar
8. Schmid, D., Ruckh, M. and Schock, H. W., Sol. Energy Mater. Sol. Cells 41/42, 281 (1996).Google Scholar
9. Rau, U. and Schock, H. W., Appl. Phys. A. 69, 131 (1999).Google Scholar
10. Hashimoto, Y., Takeuchi, K. and Ito, K., Appl. Phys. Lett. 67, 980 (1995).Google Scholar
11. Morkel, M., Weinhardt, L., Lohmuller, B., Heske, C., Umbach, E., Riedl, W., Zweigart, S. and Karg, F., Appl. Phys. Lett. 79, 4482 (2001).Google Scholar
12. Weinhardt, L., Fuchs, O., Grofl, D., Storch, G., Umbach, E., Dhere, N. G., Kadam, A. A., Kulkami, S. S. and Heske, C., Appl. Phys. Lett. 86, 062109 (2005).Google Scholar
13. Kong, S. H., Kashiwabara, H., Ohki, K., Itoh, K., Okuda, T., Niki, S., Sakurai, K., Yamada, A., Ishizuka, S. and Terada, N., Materials Research Society Symposium 865, 155 (2005).Google Scholar
14. Terada, N., Widodo, R. T., Itoh, K., Kong, S. H., Kashiwabara, H., Okuda, T., Obara, K., Niki, S., Sakurai, K., Yamada, A. and Ishizuka, S., Thin Solid Films 480-481, 183 (2005).Google Scholar
15. Sakurai, K., Hunger, R., Scheer, R., Kaufmann, C. A., Yamada, A., Baba, T., Kimura, Y., Matsubara, K., Fons, P., Nakanishi, H. and Niki, S., Prog. Photovoltaics. Res. Appl. 12, 219 (2004).Google Scholar
16. Nakada, T. and Kunioka, A., Appl. Phys. Lett. 74, 2444 (1999).Google Scholar
17. Tuttle, J. R., Contreras, M., Bode, M. H., Niles, D., Albin, D. S, Matson, R., Gabor, A. M., Tennant, A., Duda, A. and Noufi, R., J. Appl. Phys. 77, 153 (1995).Google Scholar
18. Padam, G. K., Malhotra, G. and Gupta, S. K., Solar Energy Mater. 22, 303 (1991).Google Scholar
19. Cahen, D. and Noufi, R., Sol. Cells 30, 53 (1991).Google Scholar
20. Dirnstorfer, I., Burkhardt, W., Kriegseis, W., Österreicher, I., Alves, H., Hofmann, D. M., Ka, O., Polity, A., Meyer, B. K. and Braunger, D., Thin Solid Films 361-362, 400 (2000)Google Scholar