ModelingIn−Seamorphous alloys

Abstract

The structure of amorphous ${\mathrm{In}}_{x}{\mathrm{Se}}_{y}$ $(a\text{\ensuremath{-}}{\mathrm{In}}_{x}{\mathrm{Se}}_{y})$ alloys has been studied by a first principles tight-binding molecular dynamics technique. The three-dimensional amorphous structures with different densities at different compositions were prepared by quick quenching from the liquid phase. The characteristics of short-range order, namely radial distribution functions, coordination numbers, bond angle distribution functions, and the electronic structure have been analyzed. The local bonding environments of different ${\mathrm{In}}_{x}{\mathrm{Se}}_{y}$ crystals (in particular, ${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$, InSe, and ${\mathrm{In}}_{4}{\mathrm{Se}}_{3}$) were found to be present in the amorphous phase. The average coordination number of indium is mainly four, whereas selenium is mostly two- or threefold coordinated. The majority of the bonds are heteropolar, but homopolar bonds are also present in $a\text{\ensuremath{-}}{\mathrm{In}}_{x}{\mathrm{Se}}_{y}$ so that they cannot be excluded from a realistic description of the amorphous structure. Larger content of indium in $a\text{\ensuremath{-}}{\mathrm{In}}_{x}{\mathrm{Se}}_{y}$ leads to an increased number of $\mathrm{In}\ensuremath{-}\mathrm{In}$ bonds, as expected.