Properties of intrinsic point defects in silicon determined by zinc diffusion experiments under nonequilibrium conditions

Abstract

The present paper deals with self- and foreign-atom diffusion processes in Si. We focus on the foreign-atom Zn whose diffusion behavior is shown to be influenced by intrinsic point defects like Si self-interstitials (I) and vacancies (V). Diffusion experiments with Zn in dislocation-free Si were carried out between 1208 and 870 \ifmmode^\circ\else\textdegree\fi{}C applying a special method to perform isothermal diffusion anneals as short as a few seconds. Concentration-depth profiles measured with the help of spreading-resistance analysis are completely described by simultaneous diffusion via the kickout and dissociative mechanism. The evolution of Zn diffusion with time is characterized by short-, intermediate-, and long-time diffusion regimes. Profiles belonging to the long-time regime are suitable to extract transport capacities of intrinsic defects given by the product of thermal equilibrium concentration and diffusion coefficient. Zn profiles after intermediate diffusion times are shown to be sensitive to the prevailing thermal equilibrium concentration of Si self-interstitials. Results are presented for the thermal equilibrium concentrations of self-interstitials and vacancies as well as their transport properties. From the temperature dependence of these quantities the formation and migration enthalpy of I and V are obtained. These data are compared to previous experimental results as well as theoretical calculations.