Annealing of Heavily Arsenic-Doped Silicon: Electrical Deactivation and a New Defect Complex

Ab initio total-energy calculations indicate that the formation of a new defect complex, a vacancy surrounded by four arsenic atoms, is responsible for electrical deactivation and for structural changes seen in measurements of extended x-ray-absorption fine structure when heavily arsenic-doped silicon is annealed. The $v-{\mathrm{As}}_4$ complex is energetically favored over both substitutional, isolated As in Si and substitutional $\mathrm{S}\mathrm{i}-{\mathrm{As}}_4$ configurations, and it is neutral and electrically inactive. The formation of such defects may be a widespread occurrence in silicon and in other semiconductors.