Investigation of microstructure modification of C-doped a-SiO2/Si after Pb-ion irradiation

Abstract

Thermally grown amorphous SiO 2 (a-SiO 2 ) films were implanted at room temperature (RT) with 100 keV C-ions to 5.0×10 17 ions/cm 2 . These samples were irradiated at RT with 853 MeV Pb-ions to 1.0×10 12 and 5.0×10 12 ions/cm 2 . Then the samples were investigated using Transmission Electron Microscopy (TEM) at RT. Significant microstructure modifications were observed in C-doped a-SiO 2 /Si samples after high energy Pb-ion irradiations, and the formation of new structures depended strongly on the Pb-ion irradiation fluences. For example, tracks in high density were observed in a 1.0×10 12 Pb/cm 2 irradiated and C-doped sample. Additionally, the length of tracks grows, and a large number of 8H-SiC nanocrystals can be seen in the film when irradiation fluence is increased to 5.0×10 12 Pb/cm 2 . Possible modification processes of C-doped a-SiO 2 under swift heavy ion irradiations are briefly discussed. swift heavy ion irradiation, C-doped SiO 2 , Transmission Electron Microscopy (TEM) PACS number(s): 61.72.Ww, 61.80.Jh, 68.37.Lp Citation: Liu C B, Wei K F, Yao C F, et al. Investigation of microstructure modification of C-doped a-SiO 2 /Si after Pb-ion irradiation.Silicon or silicon dioxide based light-emitting material is compatible with modern silicon planar techniques and can be applied for highly luminescent solid electro-optical displays and light-emitting diodes. As a processing technique to significantly modify the surfaces and near-surface properties of materials, ion implantation has been widely used to vary the properties of silicon-based materials. For instance, Cu [1], Ge [2,3], Si [4,5], or C [6] ions implanted into amorphous SiO 2 (a-SiO 2 ) could be used in the synthesis of ultra fine clusters that can show unique electrical and optical properties. In recent years, swift heavy ion irradiations have also been used to investigate the modification of silicon-based materials, and various phenomena such as swift heavy ion irradiations induced blue-violet photoluminescence (PL) [7-9] and new chemical bonds formations [10] in C-doped a-SiO 2 were reported. However, data on micro-structure modifications and the relationships between the PL properties and new structures is still scarce.In the present work, we aim to experimentally study structural transformations in C-doped a-SiO 2 films after swift heavy ion irradiations [11][12][13]. For this purpose, high energy Pb ion irradiations are performed and Transmission Electron Microscopy (TEM) is used in the sample analysis. Combined with other analyses, the structural modifications in C-doped a-SiO 2 films induced by swift heavy ion irradiations are investigated, and then possible mechanisms are briefly discussed.