1. P. I. Baranskii, Yu. N. Gavrilyuk, A. I. Elizarov and V. A. Kulik, Sov. Phys.-Semicond. 11 (1977) 916.
2. W. Bardsley, Progr. Semicond. 4 (1959) 156.
3. S. Cole, J. Mater. Sci. 15 (1980) 2591.
4. N. A. Goryunova, A. S. Borshevskii and D. N. Tretiakov, in ?Semiconductors and Semimetals?, Vol. 4, edited by R. K. Willardson and A. C. Beer (Academic Press, New York and London 1968) p. 3.
5. B. P. Koman and M. V. Pashovskii, Ukr. Fiz. Zh. 23 (1978) 58.