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.

Brain-inspired neuromorphic computing has shown great promise beyond the conventional Boolean logic. Nanoscale electronic synapses, which have stringent demands for integration density, dynamic range, energy consumption, etc., are key computational elements of the brain-inspired neuromorphic system. Ferroelectric tunneling junctions have been shown to be ideal candidates to realize the functions of electronic synapses due to their ultra-low energy consumption and the nature of ferroelectric tunneling. Here, we report a new electronic synapse based on a three-dimensional vertical Hf0.5Zr0.5O2-based ferroelectric tunneling junction that meets the full functions of biological synapses. The fabricated three-dimensional vertical ferroelectric tunneling junction synapse (FTJS) exhibits high integration density and excellent performances, such as analog-like conductance transition under a training scheme, low energy consumption of synaptic weight update (1.8 pJ per spike) and good repeatability (>103 cycles). In addition, the implementation of pattern training in hardware with strong tolerance to input faults and variations is also illustrated in the 3D vertical FTJS array. Furthermore, pattern classification and recognition are achieved, and these results demonstrate that the Hf0.5Zr0.5O2-based FTJS has high potential to be an ideal electronic component for neuromorphic system applications.

Semiconductive transition metal dichalcogenides (TMDs) have been considered as next generation semiconductors, but to date most device investigations are still based on microscale exfoliation with a low yield. Wafer scale growth of TMDs has been reported but effective doping approaches remain challenging due to their atomic thick nature. In this work, we report the synthesis of wafer-scale continuous few-layer PtSe 2 films with effective doping in a controllable manner. Chemical component analyses confirm that both n-and pdoping can be effectively modulated through the controlled selenization process. We systematically study the electrical properties of PtSe 2 films by fabricating top-gated field effect transistors (FETs). The device current on/off ratio is optimized in two-layer PtSe 2 FETs, and four-terminal configuration displays a reasonably high effective field effect mobility (14 and 15 cm 2 V -1 s -1 for p-and n-type FETs, respectively) with a nearly symmetric p-and n-type performance. Temperature dependent measurement reveals that the variable range hopping is dominant at low temperature. To further establish the feasible application based on controllable doping of PtSe 2 , a logic inverter and vertically stacked p-n junction arrays are demonstrated. These results validate that PtSe 2 is a promising candidate among the family of TMDs for future functional electronic applications.

To construct an artificial intelligence system with high efficient information integration and computing capability like the human brain, it is necessary to realize the biological neurotransmission and information processing in artificial neural network (ANN), rather than a single electronic synapse as most reports. Because the power consumption of single synaptic event is ∼10 fJ in biology, designing an intelligent memristors-based 3D ANN with energy consumption lower than femtojoule-level (e.g., attojoule-level) and faster operating speed than millisecond-level makes it possible for constructing a higher energy efficient and higher speed computing system than the human brain. In this paper, a flexible 3D crossbar memristor array is presented, exhibiting the multilevel information transmission functionality with the power consumption of 4.28 aJ and the response speed of 50 ns per synaptic event. This work is a significant step toward the development of an ultrahigh efficient and ultrahigh-speed wearable 3D neuromorphic computing system.

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The development of efficient methods for the enantioselective oxidation of organic molecules continues to be an important goal in organic synthesis; in particular, the use of earthabundant metal catalysts and environmentally friendly oxidants in catalytic asymmetric oxidation reactions has attracted significant interest over the last several decades. In nature, metalloenzymes catalyze a wide range of oxidation reactions by activating dioxygen under mild conditions. Inspired by selective and efficient oxidation reactions catalyzed by metalloenzymes, researchers have developed a number of synthetic model compounds that mimic the functionality of metalloenzymes. Among the reported biomimetic model compounds, tetradentate aminopyridine (N4) ligands have emerged as appealing frameworks because of their easy synthesis and facile diversification, and their complexes with metals such as Fe and Mn have proven to be versatile and powerful catalysts for a variety of (enantioselective) oxidation reactions. In this Account, we describe our efforts on the design of chiral N4 ligands and the use of their manganese and iron complexes in asymmetric oxidation reactions with H 2 O 2 as the terminal oxidant, aiming to show general strategies for asymmetric oxidation reactions that can guide the rational design of ligands and relevant metal catalysts. In studies of manganese catalysts, the arylsubstituted (R,R)-mcp [mcp = N,N′-dimethyl-N,N′-bis(pyridine-2-ylmethyl)cyclohexane-1,2-diamine] manganese complexes exhibited high enantioselectivity in the asymmetric epoxidation (AE) of various olefins with H 2 O 2 while requiring stoichiometric acetic acid as an additive for the activation of H 2 O 2 . To address this issue, we established bulkier N4 ligands for this catalytic system in which a catalytic amount of sulfuric acid enables the manganese-complex-catalyzed AE with improved stereocontrol and efficiency. In addition, this system was found to be active for the oxidative kinetic resolution of secondary alcohols. Further exploration of the structure−reactivity relationships has shown that aminobenzimidazole N4 ligands derived from L-proline, in which the conventional pyridine donors are replaced by benzimidazoles, act as promising ligands. These novel C 1 -symmetric manganese catalysts showed dramatically improved activities with unprecedented turnover numbers in the AE reactions. Notably, this class of manganese complexes can catalyze the oxidation of the C−H bonds of spirocyclic hydrocarbons and spiroazacyclic compounds in a highly enantioselective manner, providing ready access to chiral spirocyclic β,β′-diketones and spirocyclic alcohols. Remarkably, iron catalysts with these chiral N4 ligands are effective for AE of olefins, enabling rare examples of highly enantioselective syntheses of epoxides by the iron catalysts. Finally, mechanistic studies provide valuable insights into the roles of the carboxylic acid and sulfuric acid in the catalytic oxidation reactions. Thus, the results described in this Account have demonstrated the ...

With the development and application of artificial intelligence, there is an appeal to the exploitation of various sensors and memories. As the most important perception of human beings, vision occupies more than 80% of all the received information. Inspired by biological eyes, an artificial retina based on 2D Janus MoSSe was fabricated, which could simulate functions of visual perception with electronic/ion and optical comodulation. Furthermore, inspired by human brain, sensing, memory, and neuromorphic computing functions were integrated on one device for multifunctional intelligent electronics, which was beneficial for scalability and high efficiency. Through the formation of faradic electric double layer (EDL) at the metal-oxide/electrolyte interfaces could realize synaptic weight changes. On the basis of the optoelectronic performances, light adaptation of biological eyes, preprocessing, and recognition of handwritten digits were implemented successfully. This work may provide a strategy for the future integrated sensing-memory-processing device for optoelectronic artificial retina perception application.

The Rp1-D gene for resistance to maize common rust (Puccinia sorghi) is a member of a complex locus (haplotype) composed of Rp1-D and approximately eight other gene homologs. The identity of Rp1-D was demonstrated by using two independent gene-tagging approaches with the transposons Mutator and Dissociation. PIC20, a disease resistance (R) gene analog probe previously mapped to the rp1 locus, detected insertion of Dissociation in an Rp1-D mutation and excision in three revertants. Independent libraries probed with the PIC20 or Mutator probes resulted in isolation of the same gene sequence. Rp1-D belongs to the nucleotide binding site, leucine-rich repeat class of R genes. However, unlike the rust resistance genes M and L6 from flax, the maize Rp1-D gene does not encode an N-terminal domain with similarity to the signal transduction domains of the Drosophila Toll protein and mammalian interleukin-1 receptor. Although the abundance of transcripts of genes from the rp1 complex changed with leaf age, there was no evidence of any change due to inoculation with avirulent or virulent rust biotypes. A set of 27 Rp1-D mutants displayed at least nine different deletions of Rp1-D gene family members that were consistent with unequal crossing-over events. One mutation (Rp1-D*-24) resulted in deletion of all but one gene family member. Other unique deletions were observed in the disease lesion mimic Rp1-D*-21 and the partially susceptible mutant Rp1-D*-5. Different rp1 specificities have distinct DNA fingerprints (haplotypes). Analysis of recombinants between rp1 specificities indicated that recombination had occurred within the rp1 gene complex. Similar analyses indicated that the rust R genes at the rp5 locus, 2 centimorgans distal to rp1, are not closely related to Rp1-D.