Arsenic defect complexes at SiO₂/Si interfaces: A density functional theory study

The behavior of arsenic defect complexes at amorphous SiO₂/Si (110) interfaces has been studied using density-functional theory calculation. We find that arsenic defect complexes that are stable in bulk Si show moderate energy gain in SiO₂/Si interface region due to the interface-induced strain effect. We have identified three arsenic defect complex configurations, As_it, As₂ I_2I, and As₂ I _2II, which exist only at SiO₂ /Si interface. These interface arsenic defect complexes are highly stabilized due to their unique bonding configurations at SiO₂ /Si interface. Therefore, they could contribute to arsenic segregation as both initial stage precursor and dopant trapping sites. Our calculation indicates that arsenic atoms trapped in such interface complexes are electrically inactive. Finally, the formation and evolution dynamics of interface arsenic defect complexes are discussed.