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Color separation enhancement of pixn diodes by optimizing absorption regions of a-SiGe:H/a-SiC:H alloys and using a low reflective Al-doped ZnO cathode

Published online by Cambridge University Press:  07 June 2012

Andreas Bablich ,
Krystian Watty ,
Christian Merfort  and
Markus Boehm
Andreas Bablich
Affiliation:
Institute for Microsystem Technologies, Siegen University, Hoelderlinstrasse 3, 57076 Siegen, Germany.
Krystian Watty
Affiliation:
Institute for Microsystem Technologies, Siegen University, Hoelderlinstrasse 3, 57076 Siegen, Germany.
Christian Merfort
Affiliation:
Institute for Microsystem Technologies, Siegen University, Hoelderlinstrasse 3, 57076 Siegen, Germany.
Markus Boehm
Affiliation:
Institute for Microsystem Technologies, Siegen University, Hoelderlinstrasse 3, 57076 Siegen, Germany.
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Abstract

Security imaging systems working with crystalline silicon CCD or CMOS detectors are not able to distinguish colorimetrically between a large number of dangerous chemical substances, for example whitish powders [1]. In order to offer an alternative to expensive and destructive chemical methods of analysis, we developed optimized hydrogenated amorphous silicon (a-Si:H) multicolor photodiodes with different spectral response characteristics for a reliable, fast, cheap and non-destructive identification of potentially dangerous substances. Experimental optical, C-V and I-V studies were performed to explore the effect of combining linear graded a‑SiC:H-/a‑SiGe:H layers with low-reflective ZnO:Al back-contacts. Typically, a-Si:H with profiled energy gaps can be found in tandem solar cells to optimize the collection of incoming photons [2,3]. We determined the absorption coefficients of a group of a-SiC:H and a-SiGe:H graded and non-graded layers to calculate the penetration depth of photons at different energies into the device structure. Knowing the indices of absorption, refraction and extinction, it is possible to engineer diodes in such a way that accumulations of charge carriers are generated precisely at varying device depths. Common chromium back reflectors avoid a sharp falling edge of the sensitivity towards longer wavelengths and lead to interference fringes in the spectral response [4]. By combining linear graded absorption zones and ZnO:Al back contacts, we designed an optimized device with a highly precise adjustment of the spectral sensitivity reaching from 420 nm to 560 nm and reduced interference fringes at a very low reverse bias voltage of maximum -2.5 V. Similar three terminal devices allow a shift from 440 nm to 630 nm, however, at a much higher reverse bias of -11 V at 560 nm [4]. Present research efforts concentrate on the development of fast and high dynamic front illumination device structures which ensure a continuous narrow-band shift of the spectral photosensitivity and an optimum adaption to a predetermined light source-/sample measurement configuration.

Keywords

absorptionamorphousdevices
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1426: Symposium A – Amorphous and Polycrystalline Thin-Film Silicon Science and Technology—2012 , 2012 , pp. 181 - 186
Copyright
Copyright © Materials Research Society 2012

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References

REFERENCES

Bohnert, M. and Werp, J., Rechtsmedizin, 9, 218–221 (1999).CrossRefGoogle Scholar
Yang, J., Ross, R., Glatfelter, T., Mohr, R. and Guha, S., Mat. Res. Soc. Symp. Proc., 149, 435–440(1989).CrossRefGoogle Scholar
Yunaz, I.A., Hashizume, K., Miyajima, S., Yamada, A., Konagai, M., PVSC, 33, 1–5 (2008).Google Scholar
Bablich, A., Watty, K., Merfort, C., Seibel, K., Böhm, M., Mat. Res. Soc. Proc., 1305, (2011).CrossRefGoogle Scholar
Allan, D., LeComber, P. G. and Spear, W.E., Int. Conf. on Amorphous and Liquid Semiconductors Proc, 7, 323, (1977).Google Scholar
Howard, J. A. and Street, R. A., Phys. Rev. B, 44, 7935, (1991).CrossRefGoogle Scholar
Carlson, D. E., Wronski, C. R., Appl. Phys. Lett., 28, 671–673, (1976).CrossRefGoogle Scholar
Gidon, P., Giffard, B., Moussy, N., Parrein, P. and Poupinet, L., Phys. Status sol., 207 (3), 704–707, (2010).CrossRefGoogle Scholar
Koch, C., Ito, M. and Schubert, M. B., Solar Energy Mat. and Sol. Cells, 68, 227–236, (2001).CrossRefGoogle Scholar
Grove, A. S., Phys. and Techno. of Semicond. Dev., J. Wiley & Sons, 180, (1967).Google Scholar
Bayer, B. E., US Patent No.3971065 (1976).Google Scholar
Rieve, P., Giehl, J., Zhu, Q. and Boehm, M., 420, 159–164 (1996)Google Scholar
Karg, F., Kruhler, W., Moller, M. and von Klitzing, K. J., J. Appl. Phys., 60, 2016, (1986).CrossRefGoogle Scholar
Catalano, A., Newton, J. and Rothwarf, A., IEEE T. Electron. Dev., 37, 391, (1990).CrossRefGoogle Scholar
Nebel, C. E., Weller, H. C. and Bauer, G. H., Mat. Res. Soc. Symp. Proc., 118, 507, (1989).CrossRefGoogle Scholar
Mursal, A., Supu, I., Usman, T., Winata, , Sukirno, and Barmawi, M., Ind. Jounal of Physics 15 (2), 39–42, (2004).Google Scholar
Wang, Q., Schiff, E. A. and Li, Y.-M., Mat. Res. Soc. Symp. Proc., 297, 419, (1993).CrossRefGoogle Scholar
Schropp, R. E. I. and Zeman, M., M., Kluwer Academic Publishers, (1998).Google Scholar