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Crystalline Semiconductor Boron Quantum Dots
摘要： Zero-dimensional boron structures have always been the focus of theoretical research owing to its abundant phase structures and special properties. Boron clusters have been reported extensively by combining structure searching theories and photoelectron spectroscopy experiments, however, crystalline boron quantum dots (BQDs) have rarely been reported. Here we report the preparation of large-scale and uniform crystalline semiconductor BQDs from the expanded bulk boron powders via a facile and efficient probe ultrasonic approach in acetonitrile solution. The obtained BQDs have 2.46 nm in an average lateral size and 2.81 nm in thickness. Optical measurements demonstrate that strong quantum confinement effect occurs in the BQDs, implying the increase of the bandgap from 1.80 eV for the corresponding bulk to 2.46 eV for the BQDs. By injecting the BQDs into polyvinylpyrrolidone as an active layer, a BQDs-based memory device is fabricated which shows a rewriteable nonvolatile memory effect with a low transition voltage of down to 0.5 V and a high ON/OFF switching ratio of 103 as well as a good stability.
关键词： ultrasound,quantum dots,nonvolatile memory device,quantum confinement effect,boron
更新于2025-11-14 15:23:50
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New Uses of Micro and Nanomaterials || The Atomic Layer Deposition Technique for the Fabrication of Memristive Devices: Impact of the Precursor on Pre-deposited Stack Materials
摘要： Atomic layer deposition (ALD) is a standard technique employed to grow thin-film oxides for a variety of applications. We describe the technique and demonstrate its use for obtaining memristive devices. The metal/insulator/metal stack is fabricated by means of ALD-grown HfO2, deposited on top of a highly doped Si substrate with an SiO2 film and a Ti electrode. Enhanced device capabilities (forming free, self-limiting current, non-crossing hysteretic current-voltage features) are presented and discussed. Careful analysis of the stack structure by means of X-ray reflectometry, atomic force microscopy, and secondary ion mass spectroscopy revealed a modification of the device stack from the intended sequence, HfO2/Ti/SiO2/Si. Analytical studies unravel an oxidation of the Ti layer which is addressed for the use of the ozone precursor in the HfO2 ALD process. A new deposition process and the model deduced from impedance measurements support our hypothesis: the role played by ozone on the previously deposited Ti layer is found to determine the overall features of the device. Besides, these ALD-tailored multifunctional devices exhibit rectification capability and long enough retention time to deserve their use as memory cells in a crossbar architecture and multibit approach, envisaging other potential applications.
关键词： ReRAM,nonvolatile memory,complementary resistive switching cell,forming free memristive device,atomic layer deposition,redox-based resistive random access memory
更新于2025-09-23 15:21:21
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Influence of blending ratio on resistive switching effect in donor-acceptor type composite of PCBM and PVK-based memory devices
摘要： The influence of blending ratio on resistive switching effect in donor-acceptor type composite of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly(N-vinylcarbazole) (PVK)-based memory devices are investigated. Current-voltage (I-V) curves for the ITO/PCBM + PVK/Al devices with 9 wt.% of PCBM showed a current bistability with a maximum OFF/ON resistance ratio of 9 × 104, which was 100 times larger than that of the device with 23 wt.% of PCBM and was 2000 times larger than that of the device with 41 wt.% of PCBM. Furthermore, the threshold voltage obviously decreased as the PCBM concentration increases. The retention time was above 105 s indicative of the memory stability of the as-fabricated devices. The I-V characteristics at OFF state dominantly comply with the rules of space-charge-limited-current behaviors, and I-V curve at ON state obey Ohmic laws. The proposed device suggests a promising approach for adjustale OFF/ON resistance ratio and threshold voltage in electronic memory devices.
关键词： Nonvolatile memory,Resistive switching,PVK,Organic memory,PCBM
更新于2025-09-23 15:21:21
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - 50mW Average Power Gas-Plasma THz Generation Driven by a Fiber Laser
摘要： Amorphous indium–gallium–zinc oxide (a-IGZO) thin-?lm transistor nonvolatile memory devices with an IGZO charge storage layer were evaluated for the ?rst time for multi-level cell memory applications. The pristine device was de?ned as the original state (OS), which can be switched to the programmed state (PS) after a positive gate voltage pulse (for example, 12 V for 10 ms), and to the erased state (ES) after a negative gate voltage pulse (for example, ?15 V for 10 ms). The writing mechanism was attributed to Fowler–Nordheim tunneling of electrons from the channel to the charge storage layer under a positive gate bias and inverse tunneling under a negative gate bias. The devices demonstrated superior electrical programmable and erasable characteristics. A memory window of 2.4 V between OS and PS was maintained after 100 programming/erasing cycles, and a memory window of 2.66 V between OS and ES as well. The memory windows relative to OS are equal to 1.91 and 1.30 V for PS and ES, respectively, for a retention time of 105 s.
关键词： nonvolatile memory,thin-?lm transistor,multi-level cell,In-Ga-Zn-O
更新于2025-09-23 15:21:01
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Flexible nonvolatile resistive switching memory devices based on Bi<sub>2</sub>Te<sub>3</sub> nanosheets films
摘要： Flexible nonvolatile resistive switching memory is a promising candidate for next generation storage technologies. Exploring new materials is of crucial importance to achieve further performances of flexible nonvolatile resistive switching memory. In this work, topological insulator bismuth telluride (Bi2Te3) nanosheets films were introduced into firstly, a typical sandwich construction of Ag/Bi2Te3/indium tin oxide/polyethylene terephthalate with good flexibility, which exhibits nonvolatile bipolar resistive switching characteristics of operation voltage, good mechanical flexibility, and good storage stability. Furthermore, trap-controlled space charge limited current, thermionic emission are the dominant conduction mechanisms in the carrier transport. This work will provide an opportunity for Bi2Te3 nanosheets to be used in flexible electronics application.
关键词： Resistive switching,Bismuth telluride,Flexible memory,Nonvolatile,Filtration
更新于2025-09-23 15:21:01
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Nonvolatile Programmable WSe <sub/>2</sub> Photodetector
摘要： Optoelectronic devices with nonvolatile memory are an important component in a wide variety of applications ranging from optoelectronic random-access-memories, with the advantage of using optical stimuli as an added parameter, to complex artificial neuromorphic networks that pretend to mimic the working schemes of the human brain. In the past few years, 2D materials have been proposed as attractive candidates to build such optoelectronic devices with memory due to their excellent optoelectronic properties and high sensitivity to external electric fields. Here, a WSe2 monolayer p–n junction working as a nonvolatile programmable photodetector is reported, that, enabled by a split-gate configuration with embedded charge-trapping layers, is capable of retaining custom responsivity values over time, prior configuration by the user. Once configured, this photodetector can operate without external applied bias voltage as a self-driven photodetector, as well as without external back-gate voltage thanks to the charge stored in the floating gates. Furthermore, the device shows a remarkable performance, with open-circuit voltage around 1 V at approximately 270 W m?2 white light, fill factor higher than 30%, and fast response times. This programmable photodetector sets a new concept as a building block in more complex image-sensing systems.
关键词： programmable photodetector,tungsten-diselenide,2D materials,photodetectors,floating gates,nonvolatile memories
更新于2025-09-23 15:19:57
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Enhanced memory characteristics of charge trapping memory by employing graphene oxide quantum dots
摘要： In this study, graphene oxide quantum dots (GOQDs) are embedded in the charge trapping layer of high-k material HfO2 for nonvolatile memory applications. The fabricated devices exhibit a large memory window of (cid:2)1.57 V under a 63.5 V applied sweeping voltage and show only (cid:2)13.1% of charge loss after a retention time of 1.2 (cid:3) 104 s. This excellent performance is attributed to the quantum well formed in the charge trapping layer. Defect traps in the HfO2 ?lm enhance the charge trapping ef?ciency and retention property of fabricated devices. This work implies that GOQDs embedded in high-k materials are promising for charge trapping memory applications.
关键词： nonvolatile memory,graphene oxide quantum dots,HfO2,charge trapping memory
更新于2025-09-23 15:19:57
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Modeling Electrical Switching of Nonvolatile Phase-Change Integrated Nanophotonic Structures with Graphene Heaters
摘要： Progress in integrated nanophotonics has enabled large-scale programmable photonic integrated circuits (PICs) for general-purpose electronic-photonic systems on a chip. Relying on the weak, volatile thermo-optic or electro-optic effects, such systems usually exhibit limited reconfigurability along with high energy consumption and large footprints. These challenges can be addressed by resorting to chalcogenide phase-change materials (PCMs) such as Ge2Sb2Te5 (GST) that provide substantial optical contrast in a self-holding fashion upon phase transitions. However, current PCM-based integrated photonic applications are limited to single devices or simple PICs due to the poor scalability of the optical or electrical self-heating actuation approaches. Thermal-conduction heating via external electrical heaters, instead, allows large-scale integration and large-area switching, but fast and energy-efficient electrical control is yet to show. Here, we model electrical switching of GST-clad integrated nanophotonic structures with graphene heaters based on the programmable GST-on-silicon platform. Thanks to the ultra-low heat capacity and high in-plane thermal conductivity of graphene, the proposed structures exhibit a high switching speed of ~80 MHz and high energy efficiency of 19.2 aJ/nm3 (6.6 aJ/nm3) for crystallization (amorphization) while achieving complete phase transitions to ensure strong attenuation (~6.46 dB/μm) and optical phase (~0.28 π/μm at 1550 nm) modulation. Compared with indium tin oxide and silicon p-i-n heaters, the structures with graphene heaters display two orders of magnitude higher figure of merits for heating and overall performance. Our work facilitates the analysis and understanding of the thermal-conduction heating-enabled phase transitions on PICs and supports the development of the future large-scale PCM-based electronic-photonic systems.
关键词： graphene,nonvolatile,reconfigurable photonics,phase-change materials,silicon photonics,integrated nanophotonic structures
更新于2025-09-23 15:19:57
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Gatea??Couplinga??Enabled Robust Hysteresis for Nonvolatile Memory and Programmable Rectifier in Van der Waals Ferroelectric Heterojunctions
摘要： Ferroelectric field-effect transistors (FeFETs) are one of the most interesting ferroelectric devices; however, they, usually suffer from low interface quality. The recently discovered 2D layered ferroelectric materials, combining with the advantages of van der Waals heterostructures (vdWHs), may be promising to fabricate high-quality FeFETs with atomically thin thickness. Here, dual-gated 2D ferroelectric vdWHs are constructed using MoS2, hexagonal boron nitride (h-BN), and CuInP2S6 (CIPS), which act as a high-performance nonvolatile memory and programmable rectifier. It is first noted that the insertion of h-BN and dual-gated coupling device configuration can significantly stabilize and effectively polarize ferroelectric CIPS. Through this design, the device shows a record-high performance with a large memory window, large on/off ratio (107), ultralow programming state current (10?13 A), and long-time endurance (104 s) as nonvolatile memory. As for programmable rectifier, a wide range of gate-tunable rectification behavior is observed. Moreover, the device exhibits a large rectification ratio (3 × 105) with stable retention under the programming state. This demonstrates the promising potential of ferroelectric vdWHs for new multifunctional ferroelectric devices.
关键词： nonvolatile memory,programmable rectifiers,ferroelectrics,dual-gated coupling,van der Waals heterostructures,2D
更新于2025-09-23 15:19:57
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Symmetric Ultrafast Writing and Erasing Speeds in Quasi-Nonvolatile Memory via van der Waals Heterostructures
摘要： Due to the large gap in timescale between volatile memory and nonvolatile memory technologies, quasi-nonvolatile memory based on 2D materials has become a viable technology for filling the gap. By exploiting the elaborate energy band structure of 2D materials, a quasi-nonvolatile memory with symmetric ultrafast write-1 and erase-0 speeds and long refresh time is reported. Featuring the 2D semifloating gate architecture, an extrinsic p–n junction is used to charge or discharge the floating gate. Owing to the direct injection or recombination of charges from the floating gate electrode, the erasing speed is greatly enhanced to nanosecond timescale. Combined with the ultrafast write-1 speed, symmetric ultrafast operations on the nanosecond timescale are achieved, which are ≈106 times faster than other memories based on 2D materials. In addition, the refresh time after a write-1 operation is 219 times longer than that of dynamic random access memory. This performance suggests that quasi-nonvolatile memory has great potential to decrease power consumption originating from frequent refresh operations, and usher in the next generation of high-speed and low-power memory technology.
关键词： symmetric ultrafast operations,van der Waals heterostructures,quasi-nonvolatile memory
更新于2025-09-19 17:15:36