Fachbereich 11 - Physik
Institut für Materialphysik
Diffusion and Defects in Elementary and Compound Semiconductors

Interference between self- and dopant diffusion in
silicon isotope multilayer structures

This research topic concerns the simultaneous diffusion of self- and dopant atoms in silicon. Experiments on boron and arsenic diffusion in silicon isotope multilayer structures have been performed at temperatures between 850°C and 1100°C. Modelling of the simultaneous diffusion yields valuable information about the underlying mechanisms of dopant- and self-diffusion. Our experiments provide direct evidence that boron diffusion is mediated by neutral and singly positively charged self-interstitials. Simultaneous modelling of boron and silicon profiles yields data for the contributions of neutral and positively charged self-interstitials to self-diffusion. Moreover, the experiments indicate that boron diffusion is mainly mediated by the kick-out mechanism rather than by the interstitialcy mechanism which was recently proposed based on theoretical results. The simultaneous diffusion of arsenic and silicon reveals that neutral and singly negatively charged native defects mediate arsenic diffusion; no evidence of doubly charged defects was found. Additional diffusion experiments with phosphorus in silicon isotope multilayer structures are in progress to identify the nature of the native point defects which mediate self-diffusion under n-type doping.

Drittmittelgeber:

Alexander von Humboldt Foundation, State of California under the UC-SMART program, US National Science Foundation

Beteiligte Wissenschaftler:

HDoz. Dr. H. Bracht (project leader), Prof. Dr. E.E. Haller (project leader, Lawrence Berkeley National Laboratory and University of California at Berkeley, USA), Prof. Dr. A. Nylandsted Larsen (Institute of Physics and Astronomy, University of Aarhus, Denmark), Ian Sharp (Lawrence Berkeley National Laboratory and University of California at Berkeley, USA), Hughes Silvestri (Lawrence Berkeley National Laboratory and University of California at Berkeley, USA)

Veröffentlichungen:

E.E. Haller and H. Bracht: Self-diffusion in isotopically controlled semiconductors, Springer Proceedings in Physics 87 (2001) 1373-1376.

H.H Silvestri, I.D. Sharp, H. Bracht, S.P. Nicols, J.W. Beeman, J.L. Hansen, A. Nylandsted Larsen, E.E. Haller: Dopant and self-diffusion in extrinsic n-type silicon isotopically controlled heterostructures, Mat. Res. Soc. Symp. Proc. 719 (2002) F13.10.1-F13.10.6.

I.D. Sharp, H. Bracht, H.H Silvestri, S.P. Nicols, J.W. Beeman, J.L. Hansen, A. Nylandsted Larsen, E.E. Haller: Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures, Mat. Res. Soc. Symp. Proc. 719 (2002) F13.11.1-F13.11.6.

H. Bracht, H.H Silvestri, I.D. Sharp, S.P. Nicols, J.W. Beeman, J.L. Hansen, A. Nylandsted Larsen, E.E. Haller: Self- and dopant diffusion in Si isotope multilayer structures, Proceedings of the 26th. International Conference on the Physics of Semiconductors (Edinburgh, UK, 29 July - 2. August 2002), Institute of Physics Conference Series Number 171 (2003) C3.8.