Exploring the carbon distribution in carbon-doped Sb phase change materials: Insights into its microscopic mechanism for improving system thermal stability

Abstract

Through first-principles calculations and molecular dynamics simulations, we investigate carbon distribution in Sb phase-change materials and its thermal stabilization mechanism. Carbon atoms preferentially occupy Sb vacancies in crystalline states, evolving from chains to rings with increasing concentration. In amorphous phases, low-concentration carbon exists as isolated atoms/short chains, while high concentrations form graphene-like rings. Carbon doping induces shorter Sb-C/C-C bonds that distort local Sb structures, increasing three-coordinated Sb atoms and disrupting crystalline order. This structural modification suppresses crystallization and elevates crystallization temperatures. Additionally, carbon doping breaks resonant bonding in Sb, generating lone-pair electrons that enhance resistivity and reduce switching power. High-concentration carbon rings create stable van der Waals voids that fragment Sb domains, mimicking ultrathin Sb stabilization effects. Our findings demonstrate that carbon concentration controls atomic configurations in SbC materials, enabling optimized phase-change performance through tailored structural and electronic modifications.