The charge transport mechanism and electron trap nature in thermal oxide on silicon

Abstract: The charge transport mechanism of electron via traps in amorphous SiO$2$ has been studied. Electron transport is limited by phonon-assisted tunneling between traps. Thermal and optical trap energies $W\mathrm{t}=1.6$ eV, $W_\mathrm{opt}=3.2$ eV, respectively, were determined. Charge flowing leads to oxygen vacancies generation, and the leakage current increases due to the increase of charge trap density. Long-time annealing at high temperatures decreased the leakage current to initial values due to oxygen vacancies recombination with interstitial oxygen. It is found that the oxygen vacancies act as electron traps in SiO$_2$.