Abstract
Doping is indispensable to tailor phase-change materials (PCM) in optical and electronic data storage. Very few experimental studies, however, have provided quantitative information on the distribution of dopants on the atomic-scale. Here, we present atom-resolved images of Ag and In dopants in Sb2Te-based (AIST) PCM using electron microscopy and atom-probe tomography. Combing these with DFT calculations and chemical-bonding analysis, we unambiguously determine the dopants’ role upon recrystallization. Composition profiles corroborate the substitution of Sb by In and Ag, and the segregation of excessive Ag into grain boundaries. While In is bonded covalently to neighboring Te, Ag binds ionically. Moreover, In doping accelerates the crystallization and hence operation while Ag doping limits the random diffusion of In atoms and enhances the thermal stability of the amorphous phase.
Highlights
Doping is indispensable to tailor phase-change materials (PCM) in optical and electronic data storage
The atomically resolved high-angle annular dark-field (HAADF) images in Fig. 1a show that crystalline AIST annealed at 200 °C is stacked by both bilayer and quintuple-layer units
The observed atomic arrangement remains the same as that observed in Fig. 1, which suggests that the crystalline structure of AIST is barely affected by the annealing time
Summary
Doping is indispensable to tailor phase-change materials (PCM) in optical and electronic data storage. We present atom-resolved images of Ag and In dopants in Sb2Te-based (AIST) PCM using electron microscopy and atom-probe tomography. Combing these with DFT calculations and chemical-bonding analysis, we unambiguously determine the dopants’ role upon recrystallization. 1234567890():,; Over the last 50 years, computers have revolutionized almost every aspect of modern life, in particular communication, education, entertainment, and science, too Today, they face increasing demands for faster data access and larger storage capacity, which are both severely limited by the presently available memory (fast, volatile, small) and storage (slow, non-volatile, large) hierarchies[1,2]. AIST is capable of recrystallizing on the nanosecond time scale from an amorphous-crystalline rim This enables growth-dominated recrystallization behavior[11,12], which offers increased potential for DRAM/SRAM-like phase-change memory applications
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