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Cluster Simulations of Amorfous Silicon, with and without an Impurity Boron Atom

  • A. Fortunelli
  • A. Desalvo
  • O. Salvetti
  • E. Albertazzi
Part of the NATO ASI Series book series (NSSB, volume 283)

Abstract

During the past several years there has grown an enormous experimental and theoretical activity on amorphous silicon (a-Si). This is based on the possibility of doping hydrogenated amorphous silicon, which opens the way to many interesting technological applications (solar cells, etc.), despite the limitations due to the difficulty of improving the efficiency of the doping process. On the theoretical side the main effort is aimed at obtaining an understanding of the mechanisms through which the dopant atoms become electrically active. To this purpose a knowledge of the energy levels of the impurity under different configurations is of particular interest. Several theoretical models have been developed to calculate the electronic stucture of amorphous silicon (for a general review see ref. [1]), and many of them use finite cluster models based on self-consistent quantum chemical methods. The main limitation of these models lies in the small size of the clusters utilized, which cannot be indefinitely increased because of the rapid growth of the computational expense. This can be circumvented by using appropriate boundary conditions, which simulate the surronding infinite medium. In the present paper the electronic structure of a-Si and a-Si doped with an impurity boron atom is studied through ab initio Hartree-Fockplus-correlation calculations on model clusters. The choice of cluster geometries and boundary conditions is discussed in detail.

Keywords

Silicon Atom Amorphous Silicon Boron Atom Angular Distortion Lower Excited State 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    D. G. Allan, and J. D. Joannopoulos, Theory of electronic structure, in: “The physics of hydrogenated amorphous silicon”, J. D. Joannopoulos and G. Lukovsky, eds., Springer Verlag, Berlin, (1984), vol. 2.Google Scholar
  2. 2.
    A. C. Kenton, and M. W. Ribarsky, Ab initio calculations on hydrogen-bounded silicon clusters, Phys. Rev. B, 23:2897 (1981).CrossRefGoogle Scholar
  3. 3.
    J. Robertson, Dopant states in a-Si:H. I. Tight-binding-model results, Phys. Rev. B, 28:4647(1983).CrossRefGoogle Scholar
  4. 4.
    J. Robertson, Dopant states in a-Si:H. III. Triply coordinated boron, Phys. Rev. B, 28:4666 (1983).CrossRefGoogle Scholar
  5. 5.
    C. S. Nichols, and C. Y. Fong, The effects of coordination and local disorder on impurity states in hydrogenated amorphous silicon, Mat. Res. Soc. Symp. Proc., 95:57 (1987).CrossRefGoogle Scholar
  6. 6.
    J. Bernholc, Impurity induced states in amorphous hydrogenated silicon, in: “13th Int. Conf. on defects in semiconductors”, L. C. Kimerlingh and J. M. Parsey Jr., eds., Metallurgical Society of AIME, New York (1984).Google Scholar
  7. 7.
    F. Wooten, and D. Weaire, Modelling tetrahedrally bounded random networks by computer, in: “Solid State Physics”, H. Ehrenreich and D. Turnbull, eds., Academic Press, New York (1987), vol. 40.Google Scholar
  8. 8.
    P. Steinhardt, R. Alben, and D. Weaire, Relaxed continuous random networks models, J. Non-Crystalline Solids, 15:199 (1974).CrossRefGoogle Scholar
  9. 9.
    P. N. Keating, Effects of invariance requirements on the elastic strain energy of crystals, with applications to the diamond structure, Phys. Rev., 145:637 (1966).CrossRefGoogle Scholar
  10. 10.
    G. G. DeLeo, W. B. Fowler, and G. D. Watkins, Theory of off-center impurities in silicon: substitutional nitrogen and oxygen, Phys. Rev. B, 29:3193 (1984).CrossRefGoogle Scholar
  11. 11.
    K. H. Johnson, H. J. Kolari, J. P. de Neufville and D. L. Morel, Theoretical models for the electronic structures of hydrogenated amorphous silicon, Phys. Rev. B, 21:643 (1980).CrossRefGoogle Scholar
  12. 12.
    B. G. Cartling, Localized description of the electronic structure of covalent semiconductors: I. Perfect crystals, J. Phys. C, 8: 3171; 1975CrossRefGoogle Scholar
  13. 12a.
    B. G. Cartling II. Imperfect crystals, ibidem, 8:3183 (1975).CrossRefGoogle Scholar
  14. 13.
    G. G. DeLeo, G. D. Watkins, and W. B. Fowler, Many-electron effects for interstitial transition-metal impurities in silicon, Phys. Rev. B, 25:4962 (1982).CrossRefGoogle Scholar
  15. 14.
    J. C. Phillips, 1973, “Bonds and bands in semiconductors”, Academic Press, New York (1973).Google Scholar
  16. 15.
    R. Colle, A. Fortunelli, and O. Salvetti, A valence-space-only approach to the calculation of the electronic structure of many electron systems, Molec. Phys., 57:1305 (1986).CrossRefGoogle Scholar
  17. 16.
    A. Fortunelli, O. Salvetti, and G. Villani, Chemisorption of Ag on the Si(lll) surface: a theoretical study, Surf. Sci., (1991), in press.Google Scholar
  18. 17.
    R. Poirier, R. Kari, and I. G. Csizmadia, “Handbook of Gaussian basis sets”, Elsevier, Amsterdam (1985).Google Scholar
  19. 18.
    R. Colle, and O. Salvetti, A general method for approximating the electron correlation energy in molecules and solids, J. Chem. Phys., 79:1404 (1983).CrossRefGoogle Scholar
  20. 19.
    R. Colle, A. Fortunelli, N. Re, and O. Salvetti, Theoretical investigation of the ground and a few excited states of the Co(Schiff base)Li complexes, J. Am. Chem. Soc., 110:8016 (1988).CrossRefGoogle Scholar
  21. 20.
    L. Ley, Photoemission and optical properties, in: “The physics of hydrogenated amorphous silicon”, J. D. Joannopoulos and G. Lukovsky, eds., Springer Verlag, Berlin, (1984) vol. 2.Google Scholar
  22. 21.
    L. Ley, S. Kowalczyk, R. Pollack and D. A. Shirley, X-ray photoemission spectra of crystalline and amorphous Si and Ge valence bands, Phys. Rev. Letters, 29:1088 (1972).CrossRefGoogle Scholar
  23. 22.
    S. Kivelson, and C. D. Gelatt Jr., Effective mass theory in non-crystalline solids, Phys. Rev. B, 19:5160 (1979).CrossRefGoogle Scholar
  24. 23.
    S. Kivelson, and C. D. Gelatt Jr., Impurity states in a disordered insulator: the Lloyd model, Phys. Rev. B, 20:4167 (1979).CrossRefGoogle Scholar
  25. 24.
    R. A. Smith, “Semiconductors”, University Press, Cambridge (1959).Google Scholar
  26. 25.
    D. Adler, Chemistry and physics of covalent amorphous semiconductors, in: “Physical properties of amorphous materials”, D. Adler, B. B. Schwartz and M. C. Steele, eds., Plenum Press, New York (1985).Google Scholar

Copyright information

© Plenum Press, New York 1992

Authors and Affiliations

  • A. Fortunelli
    • 1
  • A. Desalvo
    • 2
  • O. Salvetti
    • 1
  • E. Albertazzi
    • 3
  1. 1.Istituto di Chimica Quantistica del C.N.R.PisaItaly
  2. 2.Dipartimento di Chimica Applicata e Scienza dei MaterialiFacoltà di IngegneriaBolognaItaly
  3. 3.Istituto Lamel del C.N.R.BolognaItaly

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