Residual defects in silicon after As⁺ion implantation at self-annealing regimes

Abstract

Rutherford backscattering (He⁺, 700 keV) and transmission electron microscopy were used to investigate the character of radiation damage in Si (001) after complete regrowth of the amorphous layer. Silicon samples were implanted with 120 keV As⁺ ions at a dose rate ∼ 50 mA/cm². It is shown that the formation and growth of inclusions takes place withing a depth of 35–150 nm from the surface at the fourth stage of high current density implantation. These inclusions are coherent with the single crystal matrix and have a wurtzite-type hexagonal structure with the lattice parameters a= 3.80 Å and c= 6.28 Å. Approximately 40 nm of the surface silicon layer retains its perfect single crystal structure after implantation. By the end of the third stage of high current density implantation silicon crystal contain very few point defects (less than 5%) within a depth between Rp and 2 Rp.