Segregation of nearest-neighbor donor-pair defects to Si∕SiO2 interfaces

Abstract

We perform first-principles density-functional calculations to study the stability of donor-pair defects at Si∕SiO2 interfaces. For P dopants, individual dopant atoms energetically favor Si lattice sites in the interface region, as compared to bulk Si. When dopant atoms aggregate to the interface region at very high dopant concentrations, dopant segregation occurs in form of electrically deactivating nearest-neighbor donor pairs that comprise two threefold coordinated dopant atoms. Our defect model explains both the redistribution and deactivation of dopant atoms observed at Si∕SiO2 interfaces.