1. S. Y. Yoon, J. Y. Oh, C. O. Kim and J. Jang, J. Appl. Phys. 84 (1998) 6463.
2. P. Müller, W. M. Holber, R. Gat, W, Henrion, E. Nebauer, V. Schlosser, I. Sieber and W. Fuhs, in Proccedings of 2nd World Conference and Exhibition on Photovoltaic Solar Energy Conversion, edited by J. Smid, H.A. Ossenbrink P. Helm, Vienna, 6–10 July 1998, p. 804.
3. J. Guillet, S. C. Soha, B. Equer, J. E. Bouree, J. P. Kleider and C. Longeaud, 2nd world Conference and Exhibition on Photovoltaic Solar Energy Conversion, edited by J. Smid, H.A. Ossenbrink P. Helm, Vienna, 6–10 july 1998, 826.
4. Y. Matsumoto and Z. Yu, Japanese J. Appl. Phys. 40 (2001) 2110.
5. A. T. Voutsas, Vaccum Sci. Tech. 3 (2001) 173.