Understanding the switching mechanism of oxygen-doped Sb phase-change material: Insights from first principles

Abstract

The crystalline–amorphous–crystalline transition process of an oxygen-tuned Sb phase-change material has been obtained by employing ab initio molecular dynamic calculations. By analyzing the local atomic arrangement and the electron structure of the SbO system, the intrinsic mechanism is explored to comprehend the material function: (1) ultrafast crystallization and difficulty in creating a glassy state of a pure Sb material might be caused by the resonance bonding of linear arrangement Sb atoms in the rhombohedral phase; (2) the impurity oxygen atoms break the medium and long-range linear arrangement of the Sb network by steric effects and change the electronic structure of these Sb atoms bonded to oxygen atoms, i.e., the obvious increase in electron localization and the great decrease in state distribution around the Fermi surface due to the high electronegativity of oxygen. These factors set an effective barrier for crystallization and improve the amorphous stability and, thus, data retention. The present research and scheme provide important insights into the engineering and manipulation of a phase-change material through first-principles calculations toward non-volatile phase change memory.