1. E. W. Williams, Phys. Rev. 168, 922 (1968).
2. F. N. Vorobkalo, K. D. Glinchuk, and A. V. Prokhorovich, Fiz. Tekh. Poluprovodn. (Leningrad) 7, 896 (1973) [Sov. Phys. Semicond. 7, 610 (1973)].
3. H. G. Guislain, L. De Wolf, and P. Clauws, J. Electron. Mater. 7, 83 (1978).
4. N. S. Averkiev, A. A. Gutkin, E. B. Osipov, et al., Fiz. Tekh. Poluprovodn. (St. Petersburg) 26, 1269 (1992) [Sov. Phys. Semicond. 26, 708 (1992)].
5. A. A. Gutkin, M. A. Reshchikov, and V. E. Sedov, Fiz. Tekh. Poluprovodn. (St. Petersburg) 34, 1201 (2000) [Semiconductors 34, 1151 (2000)].