1. W. E. Spear and P. G. LeComber, Solid State Comm., 17 (1975) 1193.
2. Y. Hamakawa, Sol. Energy Mater., IB (1982) 101.
3. K. Okuda, H. Okamoto and Y. Hamakawa, Jpn. J. Appl. Phys. Lett., 35 (1983) L605.
4. For example, Review is given in JARECT Vol.6, edited by Y. Hamakawa, “Amorphous Semiconductor - Technologies Devices”, Ohm-North Holland (1983).
5. H. Okamoto, Y. Nitta, T. Yamaguchi and Y. Hamakawa, Solar Energy Mat., 2 (1980) 313.