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 Si+ 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 Si+ fluence of 5x10(15) cm(-2). Recovery of the carriers was studied by isothermal annealing at temperatures in the range of 550-800 degreesC. 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: -dn/dt=n(gamma)C exp(-E-a/kT), with E-a=2.3 eV and gamma=2.32. 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.