Sc-Centered Octahedron Enables High-Speed Phase Change Memory with Improved Data Retention and Reduced Power Consumption

Tuning the Crystallization Mechanism by Composition Vacancy in Phase Change Materials

Interface-influenced crystallization is crucial to understanding the nucleation- and growth-dominated crystallization mechanisms in phase-change materials (PCMs), but little is known. Here, we find that composition vacancy can reduce the interface energy by decreasing the coordinate number (CN) at the interface. Compared to growth-dominated GeTe, nucleation-dominated Ge2Sb2Te5 (GST) exhibits composition vacancies in the (111) interface to saturate or stabilize the Te-terminated plane. Together, the experimental and computational results provide evidence that GST prefers (111) with reduced CN. Furthermore, the (8 - n) bonding rule, rather than CN6, in the nuclei of both GeTe and GST results in lower interface energy, allowing crystallization to be observed at the simulation time in general PCMs. In comparison to GeTe, the reduced CN in the GST nuclei further decreases the interface energy, promoting faster nucleation. Our findings provide an approach to designing ultrafast phase-change memory through vacancy-stabilized interfaces.

Pt Modified Sb2Te3 Alloy Ensuring High-Performance Phase Change Memory

Phase change memory (PCM), due to the advantages in capacity and endurance, has the opportunity to become the next generation of general−purpose memory. However, operation speed and data retention are still bottlenecks for PCM development. The most direct way to solve this problem is to find a material with high speed and good thermal stability. In this paper, platinum doping is proposed to improve performance. The 10-year data retention temperature of the doped material is up to 104 °C; the device achieves an operation speed of 6 ns and more than 3 × 10⁵ operation cycles. An excellent performance was derived from the reduced grain size (10 nm) and the smaller density change rate (4.76%), which are less than those of Ge₂Sb₂Te₅ (GST) and Sb₂Te₃. Hence, platinum doping is an effective approach to improve the performance of PCM and provide both good thermal stability and high operation speed.

Improved thermal stability and power consumption performances of Ge1Sb9 phase change thin film via doping yttrium

The effect of yttrium doping on the phase transition properties and crystal structure of Ge1Sb9 thin films was studied. Y-doped Ge1Sb9 thin films have higher crystallization temperature (218 °C) and...

Y-Doped Sb2Te3 Phase-Change Materials: Toward a Universal Memory

The disadvantages of high power consumption and slow operating speed hinder the application of phase-change materials (PCMs) for a universal memory. In this work, based on a rigorous experimental scheme, we synthesized a series of Y_xSb_2-xTe₃ (0 ≤ x ≤ 0.333) PCMs and demonstrated that Y_0.25Sb_1.75Te₃ (YST) is an excellent candidate material for the universal phase-change memory. This YST PCM, even being integrated into a conventional T-shaped device, exhibits an ultralow reset power consumption of 1.3 pJ and a competitive fast set speed of 6 ns. The ultralow power consumption is attributed to the Y-reduced thermal and electrical conductivity, while the maintained crystal structure of Sb₂Te₃ and the grain refinement provide the competitive fast crystallization speed. This work highlights a novel way to obtain new PCMs with lower power consumption and competitive fast speed toward a universal memory.

Crystal-Like Glassy Structure in Sc-Doped BiSbTe Ensuring Excellent Speed and Power Efficiency in Phase Change Memory

Phase change memory (PCM) is regarded as a promising technology for storage-class memory and neuromorphic computing, owing to the excellent performances in operation speed, data retention, endurance, and controllable crystallization dynamics, whereas the high power consumption of PCM remains to be a short-board characteristic that limits its extensive applications. Here, Sc-doped Bi_0.5Sb_1.5Te₃ has been proposed for high-speed and low-power PCM applications. An operation speed of 6 ns and a threshold current of 0.7 mA have been achieved in 190 nm Sc_0.23Bi_0.5Sb_1.5Te₃ PCM, which consumes lower power than GeSbTe and ScSbTe PCM. A good endurance of 5 × 10⁵ has been achieved, which is attributed to the small volume change of 4% during phase change and a good homogeneity phase in the crystalline state. The structure of amorphous Sc_0.23Bi_0.5Sb_1.5Te₃ has been characterized by experimental and theoretical methods, showing the existence of a large amount of crystal-like structural factions, which can efficiently minimize the atomic movements required for crystallization and subsequently improve the operation speed and power efficiency. The low diffusivity of Sc and Bi at room temperature and the rapidly increased diffusivity of Bi at elevated temperatures are fundamental for the high data retention of 94 °C and the fast crystallization in Sc_0.23Bi_0.5Sb_1.5Te₃. The combination of high atomic mobility and minimized atomic movements during crystallization ensures the high speed and low power consumption of Sc_0.23Bi_0.5Sb_1.5Te₃ PCM, which can promote its application to energy-efficient systems, that is, AI chips and wearable electronics.