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  1. Thickness-dependent reliability in 3D-Cap HfO2-based FeRAM capacitors has been studied. Results show endurance larger than 1011 cycles and >10 years of extrapolated retention time. A significant polarization gain was made possible due to trenched capacitors that enhanced the effective areas. A major cause of the endurance failure is the dielectric breakdown after numerous cycles, which is linked to the gate leakage currents. Our temperature-dependent study of I-V characteristics has revealed Fowler-Nordheim tunneling at low temperatures and Frenkel-Poole conduction at room-to-high temperatures as the culprits. Such findings will be helpful for future commercialization of this technology.
  2. Naeemi, A.J. (Ed.)
    Apparent ‘Negative Capacitance’ (NC) effects have been observed in some ferroelectric-dielectric (FE-DE) bilayers by pulse measurements, and the associated results have been published that claim to be direct evidence to support the quasi-static ‘negative capacitance’ (QSNC) idea. However, the ‘NC’ effects only occur when sufficiently high voltage is applied, and even exist in stand-alone FE capacitors. These results contradict the QSNC theory, as it predicts that once stabilized (requires a DE layer), the FE remains in the ‘NC’ state regardless of the applied voltage. In this letter, by the use of Nucleation-Limited-Switching (NLS) model, we present our results obtained frommore »simulation of pulse measurements on samples that are similar to the published ones. The simulation results indicate that reverse polarization switching occurs upon the falling edge of the pulses, which leads to the apparent hysteresis-free NC effect. This work provides an alternative interpretation of the experimental results without invoking the QSNC theory.« less
  3. Liu, M. (Ed.)
    This work presents the design and experimental demonstration of a novel dual-storage-portnonvolatile SRAM based on back-end-of-the-line processed Hf0.5Zr0.5O2-based metal-ferroelectric-metalcapacitors, which offers significant advantages over the conventional single-storage-port version withoutarea penalty, and paves the way for implementing our proposed selector-free 3D cross-point memory.
  4. We introduce an accurate and efficient method for characterizing surface wetting and interfacial properties, such as the contact angle made by a liquid droplet on a solid surface, and the vapor–liquid surface tension of a fluid. The method makes use of molecular simulations in conjunction with the indirect umbrella sampling technique to systematically wet the surface and estimate the corresponding free energy. To illustrate the method, we study the wetting of a family of Lennard-Jones surfaces by water. For surfaces with a wide range of attractions for water, we estimate contact angles using our method, and compare them with contactmore »angles obtained using droplet shapes. Notably, our method is able to capture the transition from partial to complete wetting as surface–water attractions are increased. Moreover, the method is straightforward to implement and is computationally efficient, providing accurate contact angle estimates in roughly 5 nanoseconds of simulation time.« less
  5. Free, publicly-accessible full text available January 1, 2022