Two-Dimensional WSe₂/Organic Acceptor Hybrid Nonvolatile Memory Devices Based on Interface Charge Trapping

Abstract

Two-dimensional (2D) materials, with atomic thickness and unique electronic structure, hold great potentials in electronic device applications. Charge transfer at the interface of 2D materials further provides a versatile platform for applications in electronics. Here, we report nonvolatile memory devices based on interface charge trapping between 2D WSe 2 and organic electron acceptors. The 2D WSe 2 −organic acceptor hybrid structure exhibits a high storage performance, such as large gate memory windows, high on/off ratios (>10 3 ), and long retention time (>1000 s). Further analysis revealed that organic acceptors with a stronger electron affinity (i.e., higher redox potential) have a larger electron-trapping ability and hence a better memory performance.

A generic method to control hysteresis and memory effect in Van der Waals hybrids

“…We find a very low cycle to cycle variability in the memory ratio, defined as the ratio of the on and off state current, demonstrating the reliability of these non-volatile memory devices (inset of figure 3(d)). Furthermore, the memory ratio in our devices, which can be as high as 10 8 , is comparable to state of the art sensors fabricated with two-dimensional materials, that have reported in literature (Supplementary section C.2) [52][53][54][55][56][57][58][59]. Additionally, the low bias requirements and program state current value makes the device power efficient with an observed power dissipation of ≈10pW in the program state in our MoS 2 based memory devices [51].…”

Tunable Intermediate-Logic Ternary Circuits based on MoSe2-WSe2 Heterojunction

“…40,41 As shown in Figure 2c, a memory window was originated from a large amount of charge stored in the PEDOT:PSS charge trap layer. When VErase is swept toward a positive bias, the electron carriers enter the PEDOT: PSS floating-gate through the TDL Al2O3 layer by the mechanism of Fowler-Nordheim tunneling (FNT) 42 and trap-assisted tunneling (TAT) 43 (Figure 2i and 2j) increases. It must be emphasized that the proposed inverter exhibits 100% VOUT swing with VDD-to-GND (Figure 2k).…”

Interlayer-Exciton Based Nonvolatile Valleytronic Memory

“…The energy difference of the two peaks is about 20 meV, which is consistent with the splitting energy of the conduction band of WS2 24,25 , strongly suggesting the occurrence of spintriplet excitons 26,27 . This peculiar phenomenon can be understood from the chemicaldoping 21,22 induced band-filling effect 5,28 , as depicted in Fig. 2e and 2f.…”

“…The energy difference of the two peaks is about 20 meV that is consistent with the splitting energy of the conduction band of WS 2 22,23 , strongly suggesting the occurrence of dark excitons. This peculiar phenomenon can be understood from the chemical-doping 20,21 induced bandlling effect 5,24 . Due to the type-II band alignment, electrically-doped electrons and holes reside only in the WS 2 and WSe 2 layer respectively, as illustrated in Fig.…”

“…Meanwhile, the PL intensity of 0V-2 is weaker than 0V-3 with a contrast ratio of about 1.7. It is worth to mention that the light intensity changes non-monotonously as Vg decreases from 0 V to −60 V, indicating the occurrence of chemical doping [21][22][23] , which will be discussed in the following.…”