Mechanism of formation of light-emitting silicon hexagonal phase 9R-Si

A method of photoluminescence (PL) spectroscopy has been used to study the mechanism of formation of light-emitting hexagonal 9R-Si phase by krypton ion implantation into thermally grown oxide layer on silicon substrate with subsequent annealing. The PL band at ∼ 1246 nm previously assigned to this phase appears at isochronous step-by-step annealing temperatures of 600 °C and higher as well as for one-step annealing. In addition, the PL bands at ∼1324 and ∼1408 nm previously observed in ion-implanted silicon and assigned to self-interstitial complexes are present in our case. The decrease in their intensities and simultaneous enhancement of the 9R-Si band are observed with increase in annealing temperature. It is concluded that the mechanical stresses arising in SiO₂/Si system during implantation are responsible for the formation of the 9R-Si phase. (paper)