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

Radiation enhanced diffusion in silicon

Utilising isotopically controlled ²⁸Si/^natSi multilayer structures we performed experiments on silicon self-diffusion under proton irradiation. For these experiments we used the 5 MeV Van der Graaf accelerator of the Department of Physics and Astronomy at the University of Aarhus (Denmark). The concentrations of vacancies and self-interstitials obtained during proton irradiation exceed the concentration of the native defects under thermal equilibrium conditions. Secondary ion mass spectrometry (SIMS) was performed to determine the diffusion of ³⁰Si across the ²⁸Si/^natSi interfaces which are located at various distances from the surface. The SIMS analysis reveals enhanced Si diffusion with increasing depth. This enhancement is directly correlated to the native point defect concentrations established by irradiation. The magnitude of the enhancement reveals that the concentration of vacancies in thermal equilibrium is significantly higher than the thermal equilibrium concentration of self-interstitials. Detailed modelling of the radiation enhanced diffusion, which is based on numerical solutions of the underlying kinetic equations, enables us to solve the long-standing mystery of the formation and migration properties of vacancies in silicon at high temperatures.

Drittmittelgeber:

Deutscher Akademischer Austauschdienst (DAAD)

Beteiligte Wissenschaftler:

HDoz. Dr. H. Bracht (project leader), Dr. J. Fage-Pedersen (Institute of Physics and Astronomy, University of Aarhus, Denmark), Prof. Dr. A. Nylandsted Larsen (Institute of Physics and Astronomy, University of Aarhus, Denmark), Prof. Dr. E.E Haller (Lawrence Berkeley National Laboratory and University of California at Berkeley, USA)

Veröffentlichungen:

in preparation