Enhancement of refresh time in quasi-nonvolatile memory by the density of states engineering

The recently reported quasi-nonvolatile memory based on semi-floating gate architecture has attracted extensive attention thanks to its potential to bridge the large gap between volatile and nonvolatile memory.However,the further extension of the refresh time in quasi-nonvolatile memory is limited by the charge leakage through the p-n junction.Here,based on the density of states engineered van der Waals heterostructures,the leakage of electrons from the floating gate to the channel is greatly suppressed.As a result,the refresh time is effectively extended to more than 100 s,which is the longest among all previously reported quasi-nonvolatile memories.This work provides a new idea to enhance the refresh time of quasi-nonvolatile memory by the density of states engineering and demonstrates great application potential for high-speed and low-power memory technology.

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The recently reported quasi-nonvolatile memory based on semi-floating gate architecture has attracted extensive attention thanks to its potential to bridge the large gap between volatile and nonvolatile memory.However,the further extension of the refresh time in quasi-nonvolatile memory is limited by the charge leakage through the p-n junction.Here,based on the density of states engineered van der Waals heterostructures,the leakage of electrons from the floating gate to the channel is greatly suppressed.As a result,the refresh time is effectively extended to more than 100 s,which is the longest among all previously reported quasi-nonvolatile memories.This work provides a new idea to enhance the refresh time of quasi-nonvolatile memory by the density of states engineering and demonstrates great application potential for high-speed and low-power memory technology.

Electronics based on two-dimensional materials:Status and outlook

Since Moore’s law in the traditional semiconductor industry is facing shocks,More Moore and More than Moore are proposed as two paths to maintain the development of the semiconductor industry by adopting new architectures or new materials,in which the former is committed to the continued scaling of transistors for performance enhancement,and the latter pursues the realization of functional diversification of electronic systems.Two-dimensional(2D)materials are supposed to play an important role in these two paths.In More Moore,the ultimate thin thickness and the dangling-bond-free surface of 2D channels offer excellent gate electrostatics while avoiding the degradation of carrier mobility at the same time,so that the transistors can be further scaled down for higher performance.In More than Moore,devices based on 2D materials can well meet the requirements of electronic systems for functional diversity,like that they can operate at high frequency,exhibit excellent sensitivity to the changes in the surroundings at room temperature,have good mechanical flexibility,and so on.In this review,we present the application of 2D materials in More Moore and More than Moore domains of electronics,outlining their potential as a technological option for logic electronics,memory electronics,radio-frequency electronics,sensing electronics,and flexible electronics.

Ultrafast flash memory with large self-rectifying ratio based on atomically thin MoS_(2)-channel transistor

Flash memory with high operation speed and stable retention performance is in great demand to meet the requirements of big data.In addition,the realisation of ultrafast flash memory with novel functions offers a means of combining heterogeneous components into a homogeneous device without considering impedance matching.This report proposes a 20 ns programme flash memory with 10^(8) self-rectifying ratios based on a 0.65 nm-thick MoS_(2)-channel transistor.A high-quality van der Waals heterojunction with a sharp interface is formed between the Cr/Au metal floating layer and h-BN tunnelling layer.In addition,the large rectification ratio and low ideality factor(n=1.13)facilitate the application of the MoS_(2)-channel flash memory as a bit-line select transistor.Finally,owing to the ultralow MoS_(2)/h-BN heterojunction capacitance(50 fF),the memory device exhibits superior performance as a high-frequency(up to 1 MHz)sine signal rectifier.These results pave the way toward the potential utilisation of multifunctional memory devices in ultrafast two-dimensional NAND-flash applications.