Low temperature formation of luminescent Si nanocrystals with combined process of excimer UV-light irradiation and RTA

Abstract

Si ion implantation was widely used to synthesize specimens of SiO2 containing supersaturated Si and subsequent high temperature annealing induces the formation of embedded luminescent Si nanocrystals. In this work, the potentialities of excimer UV-light (172nm, 7.2eV) irradiation and rapid thermal annealing (RTA) to achieve low temperature (below 1000°C) formation of luminescent Si nanocrystals in SiO2 have been investigated. The Si ions were introduced at acceleration energy of 180keV to fluences of 7.5×1016 and 1.5×1017ions/cm2. The implanted samples were subsequently irradiated with an excimer-UV lamp for 2h. After the process, the samples were rapidly thermal annealed at 1050°C for 5min before furnace annealing (FA) at 900°C. Photoluminescence spectra were measured at various stages at the process. Effective visible photoluminescence is found to be observed even after FA at 900°C, only for specimens treated with excimer-UV lamp and RTA, prior to a low temperature FA process. Based on our experimental results, we discuss the mechanism for the initial formation process of the luminescent Si nanocrystals in SiO2, together with the effects with excimer lamp irradiation and RTA process on the luminescence.