Theoretical studies on intrinsic electron traps in strained amorphous silica

Charge trapping in amorphous silica (a-SiO2) dielectric layer can degrade electrical performances of semicon-ductor devices. Earlier studies demonstrate that a SiO4 tetrahedra unit with a wide O-Si-O angle (>= 132.0 degrees) can act as an electron trapping site in unstrained a-SiO2 cells. With first-principle calculations, in conjunction with molecular dynamic calculations, this work investigates the impacts of uniaxial tensile strain on one-electron trapping behaviors of a-SiO2, including atomic configurations and electronic properties. Stable states of strained a-SiO2 cells with an extra electron indicate that a SiO4 with a wide O-Si-O angle (>= 132.0 degrees) and a long Si-O bond (>= 1.660 for all) making up the angle can act as a novel intrinsic electron tap. An electron trapping on this trap can generate a stable defect complex with two components: a negatively charged non-bridging oxygen hole center and a neutral oxygen vacancy with an unpaired electron.