1. A. Kalb and V. Leute, Phys. Stat. Solidi5, K199 (1971).
2. S.L. Lehoczky, J.G. Broerman, D.A. Nelson, and C.R. Whitsett, Phys. Rev. B9, 1598 (1974).
3. B. Segall and D.T.F. Marple, inPhysics and Chemistry of II-VI Compounds, ed. by M. Aven and J.S. Premer, (North Holland Publishing Co., Amsterdam, Holland, 1967), p. 319.
4. L.M. Foster and J.F. Woods, J. Electrochem. Soc.118, 1175 (1971).
5. M.B. Panish and M. Ilegems, inProgress in Solid State Chemistry, ed. by H. Reiss and J.O. McCaldin, (Pergamon Press, Elmsford, N.Y., 1972), p. 39.