Ab initio calculations were made of point-defect clusters with phosphorus, arsenic and antimony in silicon; including mixed clusters. It was shown that these dopant species interacted; modifying their diffusion and activation. Most importantly, mixed clusters could exist in similar concentrations as pure clusters, reducing the fraction of active dopants. Furthermore, the influence of cluster composition upon the configurations and energetics was analyzed. Phosphorus and arsenic atoms took on similar roles in the cluster configurations, whereas antimony led to different configurations. The binding to self-interstitials was weaker for As than for P and weaker for Sb than for As. The binding to a vacancy was stronger for As than for P and stronger for Sb than for As. For all clusters with one vacancy and up to four dopant atoms, the constant binding energy per dopant atom was -1.17eV for P, −1.27eV for As, and −1.34eV for Sb. Finally, reaction enthalpies were deduced from the calculated formation energies.

Ab initio Calculations for Point Defect Clusters with P, As, and Sb in Si. B.Sahli, K.Vollenweider, W.Fichtner: Physical Review B, 2009, 80[7], 075208