Structure, stability, and diffusion of arsenic-silicon interstitial pairs

• Published in: Applied physics letters 2005-12, Vol.87 (23), p.231905-231905-3
• Main Authors: Harrison, Scott A., Edgar, Thomas F., Hwang, Gyeong S.
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.2130398

Recent experimental studies [ A. Ural , P. B. Griffin , and J. D. Plummer , J. Appl. Phys. 85 , 6440 ( 1999 ) ; R. Kim , T. Hirose , T. Shano , H. Tsuji , and K. Taniguchi , Jpn. J. Appl. Phys. 41 , 227 ( 2002 ) ; S. Solmi , M. Ferri , M. Bersani , D. Giubertoni , and V. Soncini , J. Appl. Phys. 94 , 4950 ( 2003 ) ] have suggested the importance of Si interstitials in As transient enhanced diffusion during p n junction formation in silicon. Using density functional theory calculations within the generalized gradient approximation, we have examined the structure, stability and diffusion of As - Si i pairs. For the negatively charged As - Si i pair, we find a minimum energy structure in which the As atom bridges two approximate lattice Si atoms, while for the neutral and positively charged As - Si i we find the lowest energy structure is comprised of an As and Si i pair that is aligned in the [110] direction while sharing a lattice site. Our results suggest that in n -type extrinsic regions the diffusion of − 1 charged As - Si i pairs will be prevailing with an overall activation energy of 3.1 - 3.4 eV , while under intrinsic conditions the neutral and − 1 charged pairs will both contribute to arsenic diffusion. The predicted activation energies are similar to experimental observations for As diffusion and previous calculations for As-vacancy complex diffusion. These results clearly support that interstitials can contribute significantly to As transient enhanced diffusion, particularly in the region where interstitials exist in excess.