Bonding Nature and Optical Properties of As₂Te₃ Phase-Change Material

Chalcogenide phase-change materials (PCMs) are a promising candidate for advanced memory and computing technologies. PCM-based random access memories have entered the global memory market as storage-class memory. In these products, the element arsenic plays an essential role in the selector layers, but how arsenic stabilizes the thermal stability of the chalcogenide glass remains elusive. Herein, thorough ab initio simulations are carried out to understand the chemical bonding, electronic structure, and optical properties of an important arsenic alloy As₂Te₃ in both crystalline and amorphous forms. In comparison with the homologue alloy Sb₂Te₃, the importance of homopolar bonds in stabilizing the amorphous phase of As₂Te₃ is revealed. Also, a strategy for the design of As_xSb_2−xTe₃ alloys with optimal material properties for nonvolatile photonic phase-change applications is proposed.