Photoluminescence from Si ion irradiated SiO2/Si/SiO2 films with elevated substrate temperature

Photoluminescence (PL) from the Si ion irradiated SiO2/Si/SiO2 layers on Si substrate at room temperature and elevated substrate temperatures has been studied to elucidate the luminescence origins. The irradiation of Si ions into SiO2/Si/SiO2 layers instead of SiO2 films was performed to improve the PL intensity by increasing the number of proper-sized Si nanocrystals. Before annealing at high temperature, a luminescence band around 450 nm is observed. This luminescence band was found to originate from the diamagnetic defect known as B2 band generated by Si ion irradiation. The intensity of this band increases when ion irradiation is carried out at high substrate temperature. After annealing at high temperature, the PL peaks originating from the B2 band disappear and a new PL peak appears around 700 nm. This luminescence band is associated with ∼5-nm sized Si nanocrystals. Also it can be found that the PL peak intensity around 700 nm is significantly increased with the high substrate temperature during ion irradiation. Therefore, it is concluded that ion irradiation into SiO2/Si/SiO2 layers is more effective than ion implantation into SiO2 films to obtain an intensive PL peak originating from Si nanocrystals.