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- metal vacancies, VII (a2t2) [11]. In ZnSe, the interstitial Such a model should apply for all semiconductors.

, 1999, 41, . 830 G.D. Watkins explanation for the large lattice configurational changes References currently often being predicted in modern state-of-the-art [1] G. Feher. Phys. Rev. 103, 834 (1956).

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diamond [18] and VSi in 3CSiC [19]. However, there is an [4] G. Feher, J.C. Hensel, E.A. Gere. Phys. Rev. Lett. 5, important difference. For their a2t2 configuration, Hunds (1960).

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so far have the ability to properly include thewe multiplet Commun. 73, 393 (1990).

effects, must also beware.

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[10] G.D. Watkins. In: Deep Centers in Semiconductors / Ed. by S. Pantelides. Gordon and Breach, N.Y. (1986). Ch. 3. (This II. Present and Future provides a detailed description of the properties of the vacancy in silicon.) Intensive EPR studies continue today and will in the [11] G.D. Watkins. In: Electronic Structure and Properties of future, particularly in probing defects in the wide bandgap Semiconductors / Ed. by W. Schrter. Materials Science semiconductors of high current interest today for visible/UV and Technology. Vol. 4. VCH, Weinheim (1991). Ch. 4.

(This includes a review of vacancies and interstitials in all light emitting and high temperature electronic applications.

semiconductors.) To the arsenal of conventional EPR and ENDOR techniques [12] G.D. Watkins. In: Defects and Diffusion in Silicon Processing / discussed above have been added the powerful and greatly Ed. by T.D. de la Rubia, S. Coffa, P.A. Stolk, C.S. Rafferty.

increased sensitivity optical and electrical detection methods.

MRS Symp. Proc. Vol. 469. Pittsburgh (1997). P. 139. (This For example, the only EPR detection of an isolated interstitial is a concise review of vacancies and interstitials in silicon.) in any semiconductor has been that of the zinc interstitial [13] G.A. Baraff, E.O. Kane, M. Schlter. Phys. Rev. B21, in ZnSe, performed by optical detection methods [20,21].

(1980).

Here at the Ioffe Institute, important studies using the optical [14] E. Tarnow. Europhys. Lett. 16, 449 (1991).

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and Baranov, and much of the pioneering studies of electrical Def. Semicond. / Ed. by L.C. Kimeling and J.M. Parsey, Jr., detection have been made by Vlasenko. In addition, a great Metallurgical Soc. of AIME, Warrendale (1985). P. 269.

[16] Y. Bar-Yam, J.D. Joannopoulos. In: 13th Conf. Def. Semicond. / deal of excitement is currently centered on the possibility Ed. by L.C. Kimeling and J.M. Parsey, Jr., Metallurgical Soc.

of combining some of the various microscopic scanning of AIME, Warrendale (1985). P. 261.

techniques (optical, STM, AFM, magnetic cantilever) with [17] T.A. Kennedy, N.D. Wilsey, J.J. Krebs, G.H. Strauss. Phys. Rev.

the increased sensitivity EPR techniques to spatially resolve Lett. 50, 1281 (1983).

single defects. Promising recent success in this regard has [18] J. Isoya, H. Kanda, Y. Uchida, S.C. Lawson, S. Yamasaki, been reported by et Gruber et al [22]. Using optical confocal H. Itoh, Y. Morita. Phys. Rev. B45, 1436 (1992).

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isolated nitrogen-vacancy pair defects in diamond.

NS37, 1732 (1990).

EPR will always remain a uniquely powerful tool for [20] F. Rong, G.D. Watkins. Phys. Rev. Lett. 58, 1486 (1987).

defect identification and electronic and lattice structure [21] K.H. Chow, G.D. Watkins. Phys. Rev. Lett. 81, 2084 (1998).

[22] A. Gruber, A. Drbenstedt, C. Tietz, L. Fleury, J. Wrachtrup, determination. As new semiconducting materials and device C. von Borczyskowski. Science 276, 2012 (1997).

structures emerge in the future, it will therefore continue to play a vital role, particularly as promising new and more sensitive techniques for its detection evolve.

Acknowledgments Support for the preparation of this review was provided by the National Science Foundation under Grant N DMR92-094114, and the U.S. Navy Office of Naval Research (Electronic and Solid State Sciences Program) under Grant N N00014-94-1-0117.

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