A new class of defects in highly n-doped silicon

Abstract

Electron channeling experiments performed on individually scanned, single columns of atoms show that in highly n-type Si grown at low temperatures the primary electrically deactivating defect cannot belong to either the widely accepted class of donor–vacancy clusters or a recently proposed class of donor pairs (DPs). First-principles calculations suggest a new class of defects consisting of two dopant donor atoms near a displaced Si atom, which forms a vacancy–interstitial pair. These complexes are consistent with the present experimental results, the measured open volume of the defects, the observed electrical activity as a function of dopant concentration, and the enhanced diffusion of impurities in the presence of deactivated dopants.