1. For a review of defect-related phenomena in semiconductors, see, for example, Deep Centers in Semiconductors, edited by S. T. Pantelides, (Gordon and Breach Science Publishers, New York, 1986) or
2. Imperfections in III/V Materials, edited by E. R. Weber (Academic Press, New York, 1993).
3. J. Dabrowski and M. Scheffler, Phys. Rev. Lett. 60, 2183 (1988).
4. D. J. Chadi and K. J. Chang, Phys. Rev. Lett. 60, 2187 (1988).
5. D. J. Chadi and K. J. Chang, Phys. Rev. Lett. 61, 873 (1988).