Unraveling the optical contrast in Sb2Te and AgInSbTe phase-change materials

arXiv (Cornell University)

Abstract

Chalcogenide phase-change materials (PCMs) show a significant contrast in optical reflectivity and electrical resistivity upon crystallization from the amorphous phase and are leading candidates for non-volatile photonic and electronic applications. In addition to the flagship Ge2Sb2Te5 phase-change alloy, doped Sb2Te alloys, in particular AgInSbTe used in rewritable optical discs, have been widely investigated for decades, and nevertheless the theoretical insights on the optical properties of this important family of PCMs are scarce. Here, we carry out thorough ab initio simulations to gain an atomistic understanding of the optical properties of Sb2Te and AgInSbTe. We show that the large optical contrast between the amorphous and crystalline phase stems from the change in bond type in the parent compound Sb2Te. Ag and In impurities serve mostly the purpose of stabilization of the amorphous phase, and have marginal impact on the large variation in the dielectric function upon the phase transitions.

Authors 6

1. Shehzad Ahmed

   Xi'an Jiaotong University

   Affiliation as printed

   Center for Alloy Innovation and Design (CAID) , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China

2. Xudong Wang

   Xi'an Jiaotong University

   Affiliation as printed

   Center for Alloy Innovation and Design (CAID) , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China

3. Yuxing Zhou

   Xi'an Jiaotong University

   Affiliation as printed

   Center for Alloy Innovation and Design (CAID) , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China

4. Liang Sun
5. Riccardo Mazzarello Aachen Institute for Theoretical Solid State Physics

   RWTH Aachen University · Sapienza University of Rome · Jülich Aachen Research Alliance

   Affiliation as printed

   Department of Physics , Sapienza University of Rome , 00185 Rome , Italy

   Institute for Theoretical Solid-State Physics , JARA-FIT and JARA-HPC , RWTH Aachen University , 52056 Aachen , Germany

6. Wei Zhang

   Xi'an Jiaotong University

   Affiliation as printed

   Center for Alloy Innovation and Design (CAID) , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China

   Pazhou Lab , Guangzhou , 510320 , China