Sodium-ion implantation into silicon

The results of various detailed studies of the processes of implantational doping of silicon by sodium are reported. This review deals with following items: solubility and diffusion of sodium, radiation damage effect on diffusion of implanted sodium atoms, electrical characteristics of doped layers, specific features of defect annealing, interaction of sodium atoms with point defects, and sodium-ion implantation in the manufacture of semiconductor devices. Results show that both sodium and lithium implanted into silicon exhibit similar properties. They create in the forbidden band a single donor level with practically equal ionization energies. Their diffusion parameters are also close in the value but the slopes of the diffusion coefficients D as functions of the temperature show that the ratio DLi/DNa decreases with rising temperature