Charge-trap memory with high-κ dielectric materials is considered to be a promising candidate for next-generation memory devices. Ultrathin layered twodimensional (2D) materials like graphene and MoS2 have been receiving much attention because of their novel physical properties and potential applications in electronic devices. Here, we report on a dual-gate charge-trap memory device composed of a few-layer MoS2 channel and a three-dimensional (3D) Al2O3/HfO2/Al2O3 charge-trap gate stack. Owing to the extraordinary trapping ability of both electrons and holes in HfO2, the MoS2 memory device exhibits an unprecedented memory window exceeding 20 V. More importantly, with a back gate the window size can be effectively tuned from 15.6 to 21 V; the program/erase current ratio can reach up to 10 4 , far beyond Si-based flash memory, which allows for multi-bit information storage. Furthermore, the device shows a high mobility of 170 cm 2 V -1 s -1 , a good endurance of hundreds of cycles and a stable retention of ~28% charge loss after 10 years which is drastically lower than ever reported MoS2 flash memory. The combination of 2D materials with traditional high-κ charge-trap gate stacks opens up an exciting field of novel nonvolatile memory devices. KEYWORDS. Charge-trap memory, MoS 2 , Memory window, Dual gate, Memory characteristics 3 Atomically thin 2D materials like graphene and MoS 2 has been extensivelystudied recently because of their promising applications in optoelectronics 1, 2 , spintronics 3-7 , transparent and flexible devices [8][9][10][11][12] . Due to its remarkable properties, such as high carrier mobility and mechanical flexibility, graphene has been incorporated into nonvolatile memory structures serving as a floating gate 13,14 or a transparent channel 15 . However, owing to its zero band gap 16 , the graphene channeled memory devices typically possess a low program/erase current ratio, which significantly hinders its application in nonvolatile memory devices. Unlike graphene, MoS 2 has a transition from indirect band gap (1.2 eV) to a direct band gap (1.8 eV) in monolayer 17,18 . Its field effect transistors 19 show a high mobility of 200 cm 2 V -1 s -1 with a high on/off ratio approximately 10 8 . To potentially enhance the program/erase current ratio, attempts were made to replace graphene with MoS 2 as a channel material in a ferroelectric memory 20 or as a charge-trap layer in a graphene flash memory 21 . It was demonstrated that the monolayer MoS 2 is very sensitive to the presence of charges 14 . However, the relatively small memory window, the degraded mobility, and the insufficient trap capability in those devices require further improvement of the chargetrap stack in the MoS 2 memory device.

In this letter polarization fatigue in ferroelectric polymers has been reported. Experimental results indicate that the driving voltages with lower frequency and higher amplitude should correspond to higher fatigue rates. A universal scaling behavior with N∕f, where N is the number of switching cycles and f is the frequency, is found in the frequency dependence of polarization fatigue. The profile of driving voltages is also found to affect the fatigue behavior. It is believed that the trapped charges, injected from electrodes into films, should make the major contribution to polarization fatigue.

user and the environment in order to avoid any dangerous contact between the robot and the unwanted objects or obstacles. Currently several proximity sensors have been reported with sensing mechanisms relying on optical imaging, [2] ultrasound, [1b] triboelectric effect, [3] and change in capacitance. [4] The maximum sensing distance is a basic consideration for design of these proximity sensors. A large sensing distance usually means long response time for a robot to avoid unexpected collisions and consequent damage. The maximum sensing distance for capacitance-, triboelectric-, and ultrasound-type sensors can reach up to several tens of centimeters, [1b,3,4c,e] while it is only about 3 cm for electret-type sensors. [5] It is also noted that, when triboelectric effect was integrated with a p-type silicon-based field effect transistor (FET), the effective sensing distance was only about 80 µm. [6] Recently Wang et al. developed flexible proximity sensors based on organic crystal sheets. [7] Organic semiconductor rubrene nanobelts were synthesized by physical vapor transport method and then mechanically transferred to flexible poly(ethylene terephthalate) substrates to construct two-terminal devices. Such devices could perceive the approach of human finger, fiber, and even atomic force microscopy tip. However, their reported sensing distance is limited only to several millimeters, and the fabrication process of such devices is also expected to be further simplified. Since the appealing route for the fabrication of organic semiconducting films and related devices is usually solution based, including spin coating, [8] dip coating, [9] push coating, [10] solution shearing, [11] printing, [12] and so on, solution fabrication of organic semiconductor-based proximity sensors is highly expected.Here we reported the solution-based fabrication of organic semiconductor-based proximity sensors designed with FET configuration. Organic semiconducting poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno [3,2-b] thiophene)] (DPP-DTT) was used as the active layer which was deposited by the conventional spin-coating technique. Extended gate electrode was used as the sensing element. DPP-DTT has been widely studied in organic FET devices with high carrier mobility and good air stability. [13] Several reports have shown that mobility of DPP-DTT based FET devices was significantly In recent years human-machine interaction has become increasingly important in industrial applications and daily life. Proximity sensors are expected to become an important part of such systems. The mechanisms of these sensors are usually based on ultrasound, capacitance, triboelectric effect, optical imaging or semiconducting devices. The fabrication and sensing performance of solution-based organic transistor proximity sensors is reported. To enhance electrical performance, nanogroove templates are introduced to guide the oriented growth of organic semiconducting layer. The templates are realized by friction-transferri...

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In recent years ferroelectric polymers have attracted much attention due to their potentials in flexible electronics. To satisfy the requirements of low operation voltage and low power consumption, it is required to reduce the ferroelectric film thickness down to, for example, 100 nm. However, decreased film thickness results in low crystallinity and thus worse electrical performance. One possible solution is to realize the epitaxial growth of ferroelectric thin films via effective control of structure and orientation of ferroelectric crystals. Here we report our work on poly­(tetrafluoro­ethylene)-template-induced ordered growth of ferroelectric thin films. We focus on the study of thermal stability of ferroelectric phase in these ferroelectric films. Our work indicates that epitaxial growth effectively increases the crystallinity and the melting and ferroelectric phase transition temperatures and implies the extended application of ferroelectric devices at higher temperature.