Electronic structure, charge distribution, and charge transfer in alpha- and beta-Si3N4 and at the Si (111)/Si3N4(001) interface

The electronic structure, charge distribution, and charge transfer in α- and β- $\rm Si_3N_4$ and at the $\rm Si(111)/Si_3N_4(001)$ interface have been studied using a self-consistent first-principles LCAO method. The calculated charge transfer suggests that both in α- and β-phases, the ionic formula may be written as $\rm Si_3^{+1.24}N_4^{-0.93}$. For the $\rm Si(111)/Si_3N_4(001)$ interface, the silicon atoms from the $\rm Si(111)$ side give some electrons to the N atoms of $\rm Si_3N_4$ forming the Si-N bonds at the interface. One Si-N bond is associated with a charge transfer of about 0.31 electrons