Atomistic structure of amorphous silicon nitride from classical molecular dynamics simulations

Abstract

By means of molecular dynamics simulations based on the Billeter et al. [S.\nR. Billeter, A. Curioni, D. Fischer, and W. Andreoni, Phys. Rev. B {\\bf 73},\n155329] environment-dependent classical force field we studied the structural\nfeatures of SiN$_x$ samples at various stoichiometries. Our results are in good\nagreement with experimental data and are able to reproduce some features which\nso far were not reproduced by simulations. In particular, we identified units\ncontaining N--N bonds, which are thought to be responsible for an unassigned\npeak in the radial distribution function obtained from neutron diffraction data\nand signals observed in electron spin resonance, X-ray photoemission\nspectroscopy, electron-energy-loss spectroscopy and optical absorption\nexperiments.\n We have identified defects which are thought to be the responsible for the\nhigh concentration of charge traps that makes this material suitable for\nbuilding non-volatile memory devices. We analyzed the dependency of the\nconcentration of these defects with the stoichiometry of the sample.\n