Recovery of the carrier density in arsenic-doped silicon after high energy 2 MeV Si¿ implantation

Carrier density and mobility measurements were performed on heavily arsenic-doped silicon-on-insulator specimens after 2 MeV implantation of Si1 ions. It is found that implantation induces a marked reduction of the electron density, which increases with the concentration of active dopant, and approaches saturation for a Si1 fluence of 531015 cm22. Recovery of the carriers was studied by isothermal annealing at temperatures in the range of 550-800 °C. It is shown that this phenomenon can be separated by As deactivation, which takes place at the same time, and that the kinetics of carrier recovery can be expressed by the rate equation: 2dn/dt5ngC exp(2Ea /kT), with Ea52.3 eV and g52.32. The recovery rate increases with As concentration, and values of C that account for this phenomenon are reported. These results and the annealing behavior of the carrier mobility in the damaged and undamaged reference samples indicate that the decrease of the carrier density upon irradiation can be attributed to acceptor centers, probably due to point defects clusters.