High-dose MeV electron irradiation of Si-SiO2 structures implanted with high doses Si+

Abstract

The influence was studied of 22-MeV electron irradiation on Si-SiO₂ structures implanted with high-fluence Si⁺ ions. Our earlier works demonstrated that Si redistribution is observed in Si⁺-ion-implanted Si-SiO₂ structures (after MeV electron irradiation) only in the case when ion implantation is carried out with a higher fluence (10¹⁶ cm^-2). We focused our attention on the interaction of high-dose MeV electron irradiation (6.0×10¹⁶ cm^-2) with n-Si-SiO₂ structures implanted with Si⁺ ions (fluence 5.4×10¹⁶ cm^-2 of the same order magnitude). The redistribution of both oxygen and silicon atoms in the implanted Si-SiO₂ samples after MeV electron irradiation was studied by Rutherford back-scattering (RBS) spectroscopy in combination with a channeling technique (RBS/C). Our results demonstrated that the redistribution of oxygen and silicon atoms in the implanted samples reaches saturation after these high doses of MeV electron irradiation. The transformation of amorphous SiO₂ surface into crystalline Si nanostructures (after MeV electron irradiation) was evidenced by atomic force microscopy (AFM). Silicon nanocrystals are formed on the SiO₂ surface after MeV electron irradiation. The shape and number of the Si nanocrystals on the SiO₂ surface depend on the MeV electron irradiation, while their size increases with the dose. The mean Si nanocrystals height is 16-20 nm after irradiation with MeV electrons at the dose of 6.0×10¹⁶ cm^-2.