Ab initio shallow impurity level calculations in semiconductors

Binding energies of B, Al, Ga, In and Tl shallow acceptors in bulk Si were calculated using a GW + Semi-empirical procedure. Within the procedure, both density functional theory calculation within local density approximation (LDA) and GW calculation were performed. In the LDA calculation, a large supercell containing tens of thousands of Si atoms and the center impurity atom was constructed from a potential patching procedure. The central potential of this system was further corrected by 64 atom GW calculations. The folded spectrum method was used to calculate the eigen energies of this large supercell containing the center impurity. The calculated binding energies show good agreement with experimental impurity binding energies. This procedure represents an efficient approach to study shallow impurity levels which are important for semiconductor devices.