Arsenic defect complexes atSiO2/Siinterfaces: A density functional theory study

Abstract

The behavior of arsenic defect complexes at amorphous ${\text{SiO}}_{2}/\text{Si}$(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 ${\text{SiO}}_{2}/\text{Si}$ interface region due to the interface-induced strain effect. We have identified three arsenic defect complex configurations, ${\text{As}}_{\text{i}t}$, ${\text{As}}_{2}{\text{I}}_{2I}$, and ${\text{As}}_{2}{\text{I}}_{2II}$, which exist only at ${\text{SiO}}_{2}/\text{Si}$ interface. These interface arsenic defect complexes are highly stabilized due to their unique bonding configurations at ${\text{SiO}}_{2}/\text{Si}$ 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.