1. A. V. Oleinich-Lysyuk, N. P. Beshlei, and I. M. Fodchuk, Fiz. Tekh. Poluprovodn. (St. Petersburg) 37, 1337 (2003) [Semiconductors 37, 1299 (2003)].
2. O. G. Vlokh, A. V. Kityk, O. M. Mokryi, and V. G. Gribik, Fiz. Tverd. Tela (Leningrad) 33, 312 (1991) [Sov. Phys. Solid State 33, 181 (1991)].
3. B. F. Borisov, T. Kraevskii, A. K. Radzhabov, and E. V. Charnaya, Fiz. Tverd. Tela (St. Petersburg) 35, 241 (1993) [Phys. Solid State 35, 127 (1993)].
4. V. G. Eremenko and V. I. Nikitenko, Phys. Status Solidi A 14, 317 (1972).
5. P. Pirouz, R. Chaim, and J. Samuels, Izv. Akad. Nauk SSSR, Ser. Fiz. 51, 753 (1987).