First-principles supercell calculations for simulating a shallow donor state in Si

Abstract

We present first-principles simulations of As-doped Si carried out using several cubic supercells of up to 10 648 atoms. The 1s As donor level in each supercell splits into three states, which have A 1 , T 2 , and E symmetries, respectively. The 1 s ( A 1 ) wavefunction is well converged in the largest cell, and its spread is close to those of the effective-mass theories. However, the calculated binding energies are smaller than experimental values. This discrepancy would be due to the self-interaction error within the approximated exchange-correlation density functional used in this calculation. Therefore, we also show perturbative calculations based on an impurity potential without the self-interaction error to estimate the binding energies of the 1 s ( A 1 ) donor state. The estimated binding energy in the largest supercell agrees well with the experimental value.