Crystalline Si samples were implanted at room temperature with 40 keV He ions at a dose of 5×1016 cm-2

and then subjected to thermal annealing at different temperatures. Various techniques

such as transmission electron microscopy(TEM)

thermal desorption spectroscopy(THDS) and photoluminescence(PL)

have been used to investigate damage creation

helium release

luminescence properties and their thermal evolutions. Our results clearly show that He ion implantation followed by annealing induces formation of a well-defined band of cavities. Helium thermal release occurs in two distinguished temperature regions

which correspond to helium release from smaller vacancy-like defects and cavities

respectively. Moreover

He ion implantation can also induce luminescence centers in silicon

which gives rise to photoluminescence bands centered at wavelengths of about 680 nm and 930 nm

respectively. The PL bands may be associated with the formation of silicon nano-clusters produced by the He ion implantation and subsequent thermal annealing.