EFFECT OF IMPURITY CORE SQUEEZING ON DONOR ENERGY-LEVELS IN SILICON

Using first principle Pseudo Impurity Theor) (PIT) and variational met hod, the binding energies of group V shallow donors in silicon are est imated incorporating the effect of core squeezing of the substitutiona l impurity atoms, with an empirical squeezing scheme of the core orbit als. Scaling factors are defined for various core states of the impuri ty atom to take explicit account of the varying degree of rigidity on squeezing. From the extent of squeezing required to reproduce the expe rimental binding energies of the donors, the local relaxation due to t he size difference between the host and donor atoms is deduced and com pared with experimental results and theoretical predictions available in literature. It is demonstrated that the squeezing scheme of the pre sent work combined with the First principle pseudo impurity theory cou ld deduce information about a purely local phenomenon such as lattice distortion reasonably well from the binding energy of the donor impuri ty.