Radiation Effect on the Electron Transport Properties of SiO2/Si Interface: Role of Si Dangling-Bond Defects and Oxygen Vacancy

Radiation effect of electronic devices is a complex issue that attracted a lot of interest in the area of aviation industry and nuclear engineering. In order to investigate the relationship between structure damage and electrical performance of electronic devices, first-principle modeling and calculations were carried out to link SiO2/Si interfacial defect states and electron transport properties of electronic devices. We found that the oxygen vacancy (VO) is much more easier to form than silicon vacancy ($\textbf{V}_{\mathbf {Si}}$) under the radiation environment. The band structure shows that two defect levels were localized inside the band gap of the SiO2/Si interface, approximately 0.19 eV and 0.25 eV below the conduction band minimum (CBM) as electronic traps, which were induced by a Si dangling bond defects. The $\textbf{V}_{\mathbf {O\, }}$ as the donor defect makes the interface restructuring and chemical bond changing, which leads to the defect level crossing the Fermi level ($E_{\mathbf {F}}$). Oxygen atoms of SiO2 at the interface act as a potential well to keep electrons from tunneling. The barrier for carriers disappear after oxygen atom being moved, which will reduce the electrical gain and breakdown strength of devices. Our results gave a physical interpretation to the relationship between defects and electrical performance of electronic materials and indicated that the dangling bonds and $\textbf{V}_{\mathbf {O}}$textbf at the interface are needed to be suppressed generating in order to harden the electronic devices.