Polarized Tunneling Transistor for Ultrafast Memory

Abstract

In today's information age, high performance nonvolatile memory devices have become extremely important. Despite their potential, existing devices suffer from limitations, such as low operation speed, low memory capacity, short retention time, and a complex preparation process. To overcome these limitations, advanced memory designs are required to improve speed, memory capacity, and retention time and reduce the number of preparation steps. Here, we present a nonvolatile floating-gate-like memory device based on a transistor that uses the polarization effect of ferroelectric material PZT (Pb[Zr 0.2 Ti 0.8 ]O 3 ) for regulating tunneling electrons for charging and discharging the MoS 2 channel layer. The transistor is defined as a polarized tunneling transistor (PTT) and does not require a tunnel layer or a floating-gate layer. The PTT demonstrates an ultrafast programming/erasing speed of 25/20 ns and a response time of 120/105 ns, which is comparable to the ultrafast flash memories based on van der Waals heterostructures. Additionally, the PTT has a high extinction ratio of 10 4 , a long retention time of 10 years, and a simple fabrication process. Our research provides future guidelines for the development of the next generation of ultrafast nonvolatile memory devices.

PZT-Enabled MoS2 Floating Gate Transistors: Overcoming Boltzmann Tyranny and Achieving Ultralow Energy Consumption for High-Accuracy Neuromorphic Computing

“…A detailed description of the PFGT preparation steps is provided in Figure S1. The ferroelectric property of PZT has been confirmed in recent research . The 2.8 nm thickness of MoS 2 (Figure c) indicates that it consists of approximately four layers.…”

“…Artificial synapses are primarily configured using either two-terminal memristors − or three-terminal transistors. − ,− However, memristor-based artificial synapses possess shared reading and writing terminals, leading to inevitable destructive weight updates, , and subsequent degradation of operational precision in neuromorphic computing systems. Three-terminal transistor-based artificial synapses, featuring separate writing (gate) and reading (drain) terminals, benefit from a nondestructive weight-update function and have attracted significant academic interest. − ,− The weight updates of these artificial synapses have been modulated using various charge-storage mechanisms, such as interfacial traps, ,− floating gates, , ferroelectric polarization switching, , ion intercalation, , and defects in dielectrics. , Artificial synapses are essential components of artificial neural networks (ANNs), and their high-precision computation relies on high-density conductance states stemming from the wide hysteresis window of three-terminal transistors. Consequently, optimizing device engineering to enhance the wide hysteresis window of three-terminal transistors has significant implications for the development of ANN-based neuromorphic computation systems.…”

Polarized Tunneling Transistor for Ultralow-Energy-Consumption Artificial Synapse toward Neuromorphic Computing

“…Figure c presents our PTT fabricated using a PZT-enabled MoS 2 FET, with detailed PTT preparation steps provided in Figure S1. The high-quality, wafer-level PZT film’s ferroelectric property has been verified in recent research . Optical image of the PTT is illustrated in Figure d, and its corresponding atomic force microscopy (AFM) image is shown in Figure e, which indicates that the MoS 2 thickness is 2.2 nm (approximately 3 layers).…”

“…The PZT exploits its inherent polarization properties to maintain stable prolonged program and erase states. Conversely, since Al 2 O 3 lacks the inherent polarization effect, employing it as a substitute for the PZT would lead to an inability to sustain the program and erase states over an extended period . As shown in Figure b, although the positive and negative voltage pulses have the same absolute voltage value, the negative voltage pulse generates the erasing electric field while the positive voltage pulse produces the programming electric.…”

A metastable small organic molecule for secure memory devices

“…6–16 As part of the family of electronic devices, organic electrical memory devices have attracted enormous attention. 17–33 Recently, stimuli-responsive materials have been introduced into organic electrical memory devices realizing novel performance. For example, Song and co-workers developed photoinduced multilevel memory devices whose performance could be easily tuned and controlled from bistable switching behaviour to tristable switching behaviour through UV light.…”