Theoretical studies on intrinsic electron traps in strained amorphous silica

Abstract

Charge trapping in amorphous silica (a-SiO2) dielectric layer can degrade electrical performances of semiconductor devices. Earlier studies demonstrate that a SiO4 tetrahedra unit with a wide O-Si-O angle (≥132.0∘) 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∘) and a long Si-O bond (≥1.660Å) 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.