Electric field reduced charging energies and two-electron bound excited   states of single donors in silicon
  We present atomistic simulations of the D0 to D- charging energies of a gated donor in silicon as a function of applied fields and donor depths and find good agreement with experimental measure- ments. A self-consistent field large-scale tight-binding method is used to compute the D- binding energies with a domain of over 1.4 million atoms, taking into account the full bandstructure of the host, applied fields, and interfaces. An applied field pulls the loosely bound D- electron towards the interface and reduces the charging energy significantly below the bulk values. This enables formation of bound excited D-states in these gated donors, in contrast to bulk donors. A detailed quantitative comparison of the charging energies with transport spectroscopy measurements with multiple samples of arsenic donors in ultra-scaled FinFETs validates the model results and provides physical insights. We also report measured D-data showing for the first time the presence of bound D-excited states under applied fields. 
R. Rahman, G. P. Lansbergen, J. Verduijn, G. C. Tettamanzi, S. H.   Park, N. Collaert, S. Biesemans, G. Klimeck, L. C. L. Ho...
cond-mat.mes-hall