1. Yu. V. Shmartsev and M. Mirzabaev, Fiz. Tekh. Poluprovodn.,5, No. 11, 2245 (1971).
2. E. V. Kozeev and E. A. Makarov, in: Semiconductor Physics and Engineering [in Russian], Izd. NéTI, Novosibirsk (1968).
3. S. Masakazu and M. Hiroyoki, Jap. J. Appl. Phys.,11, No. 5, 767 (1972).
4. I. P. Zhad'ko, V. A. Romanov, and B. K. Serdega, Prib. Tekh. éksp., No. 5, 215 (1972).
5. V. L. Kon'kov and Z. I. Islamov, Izv. Vyssh. Uchebn. Zaved., Fiz., No. 4, 91 (1970).