Modeling dynamic clustering of arsenic including non-negligible concentrations of arsenic-point defect pairs

The time dependent deactivation of RTA-activated arsenic-doped samples was studied for chemical concentrations from 2·10²⁰ cm^-3 to 1·10²¹ cm^-3 in the temperature range from 700°C to 900°C using a newly developed experimental set-up. It is based on the use of homogeneously doped SOI material which helped to avoid experimental problems, allowed a repeated usage of the same samples, and simplified the interpretation of the electrical measurements. The dependence of the active concentrations after long-time anneals on the total concentration indicated that the deactivation behavior can be described by a simple cluster law. But even at low concentrations it was reported in the literature that the electron concentration is significantly below the total arsenic concentration. This was attributed to pair formation between arsenic atoms and intrinsic point defects. Intended as an engineering model, the model proposed here combines both approaches and gives a consistent dynamical description of the electrically active arsenic concentration from low to high concentrations