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Evidence for reversible oxygen ion movement during electrical pulsing: enabler of the emerging ferroelectricity in binary oxides
doi: 10.1088/2752-5724/ad3bd5
Evidence for reversible oxygen ion movement during electrical pulsing: enabler of the emerging ferroelectricity in binary oxides
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摘要: Ferroelectric HfO2-based materials and devices show promising potential for advancing emerging information technology but face challenges with inadequate electrostatic control, degraded reliability, and serious variation for EOT (effective oxide thickness) scaling. We demonstrate a novel interface-type switching strategy to realize ferroelectric characteristics in atomic-scale amorphous binary oxide films, which are formed in oxygen-deficient conditions by atomic layer deposition (ALD) at low temperatures. This approach can avoid the shortcomings of reliability degradation and gate leakage increment in scaling poly-crystalline doped HfO2-based films. Through theoretical modeling and experimental characterization, we show that: 1) Emerging ferroelectricity exists in the ultrathin oxide system due to microscopic ion migration in the switching process. 2) These ferroelectric binary oxide films are governed by the interface-limited switching mechanism, which can be attributed to the oxygen vacancy migration and the surface defect related to electron (de)trapping. 3) Transistors featuring ultrathin amorphous dielectrics, used for nonvolatile memory applications with an operating voltage reduced to ±1 V, have also been experimentally demonstrated. These findings suggest that the strategy is a promising approach to realizing the next-generation CMOS with scalable ferroelectric material.Abstract: The performance of red InP and blue ZnTeSe-based quantum dots (QDs) and corresponding QD light emitting diodes (QLEDs) has already been improved significantly, whose external quantum efficiencies (EQEs) and luminances have exceeded 20% and 80,000 cd m-2, respectively. However, the inferior performance of the green InP-based device hinders the commercialization of full-color Cd-free QLED technology. The ease of oxidation of the highly reactive InP cores leads to high non-radiative recombination and poor photoluminescence quantum yield (PL QY) of the InP-based core/shell quantum dots (QDs), limiting the performance of the relevant QLEDs. Here, we proposed a fluoride-free synthesis strategy to in-situ passivate the InP cores, in which zinc myristate reacted with phosphine dangling bonds to form Zn-P protective layer and protect InP cores from the water and oxygen in the environment. The resultant InP/ZnSe/ZnS core/shell QDs demonstrated a high PL QY of 91%. The corresponding green-emitting electroluminescence devices exhibited a maximum EQE of 12.74%, along with a luminance of over 175,000 cd m-2 and a long T50@100 cd m-2 lifetime of over 20,000 h.
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Key words:
- Ferroelectric /
- Binary oxide /
- Mobile ion /
- Amorphous dielectric /
- Nonvolatile memory
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