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(SiTe)2(Sb2Te3) n phase-change superlattices were investigated theoretically and experimentally. Ab-initio first principle simulations predicted that the (SiTe)2(Sb2Te3) n structures are stable and possess a Dirac semimetal-like band structure. Calculation of the Z2 invariant indicated that the structure was topologically nontrivial. (SiTe)2(Sb2Te3) n superlattice structures derived from first-principles were successfully fabricated on a Si substrate by RF-magnetron sputtering. XRD and TEM indicated that the superlattice films were highly oriented with the 00 X planes of Sb2Te3 and the superlattice normal to the substrate surface. The (SiTe)2(Sb2Te3) n superlattice is suggested as new material system for interfacial phase-change memory applications. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Phase‐change materials (PCMs) based on Ge–Sb–Te alloys are a strong contender for next‐generation memory technology. Recently, PCMs in the form of GeTe–Sb2Te3 superlattices (CSLs) have shown superior performance compared to ordinary PCM memory, which relies on switching between amorphous and crystalline phases. Although detailed atomic structure switching models have been developed with the help of ab‐initio simulations, there is still fierce scientific debate concerning the experimental verification of the actual crystal structures pertaining to the two CSL memory states. One of the strongest techniques to provide this information is (scanning) transmission electron microscopy ((S)TEM). The present article reviews the analyses of CSLs using TEM‐based techniques published during the last seven years since the seminal 2011 Nature Nanotechnology paper of Simpson et al., showing the superior performance of the CSL memory. It is critically reviewed what relevant information can be extracted from the (S)TEM results, also showing the impressive progress that has been achieved in a relatively short time frame. Finally, an outlook is given including several open questions. Although debate on actual switching mechanism in CSL memory is clearly not settled, still there is consensus in this field that CSL research has a bright future. Chalcogenide superlattices (CSLs) based on GeTe–Sb2Te3 have shown superior performance compared to ordinary phase‐change memory relying on GeSbTe alloys. Here, the authors critically review the structural characterization of CSLs that has been performed in recent years using transmission electron microscopy (TEM). Undoubtedly TEM‐based techniques will finally resolve the actual structures holding for the two CSL memory states. [ABSTRACT FROM AUTHOR]

Phase change memory (PCM) device physics comprehension represents an important chapter of future development of the PCM‐based architectures and their placement into the storage class memory (SCM) segment of the memory hierarchy. Here, a reduction of SET and RESET currents by more than 60% with respect to conventional GeTe–Sb2Te3 (GST) alloys is demonstrated by using phase change memory cells containing (GeTe–Sb2Te3)/Sb2Te3 super‐lattices (SL). Further, it is demonstrated that our SL PCM devices have similar characteristics in terms of the memory transition as conventional memory cells based on GST, even though showing reduced power consumption, indicative of an efficiency augmented SET‐to‐RESET transition. The reduced power consumption may be attributed to an increased thermal resistance of the SL with respect to the bulk GST alloy. This demonstrates that it is possible to engineer PCM with enhanced performance by employing SL structures, enlarging the possibility of employing SL as SCM players. A 60% reduction of currents in phase change memory (PCM) with super‐lattice (SL) active stacks is reported with respect to bulk stacks. Similarities between the electrical properties of SL and bulk PCM are pointed out in terms of programming curves and SET behavior, paving the way for a thermal‐based working principle in SL PCM as in the bulk counterpart. [ABSTRACT FROM AUTHOR]