Emulating key synaptic functions in electronic devices is quite significant in bioinspired applications. Artificial synaptic thin film transistors (TFT) offer a promising solution for efficient synapse simulation. Herein, artificial synapses based on indium–gallium–zinc oxide (IGZO) TFT are fabricated and the photoelectric plasticity is investigated. Versatile synaptic functions including paired‐pulse facilitation, paired‐pulse depression, and short‐term memory to long‐term memory transition are emulated. More importantly, these synaptic functions can be mediated by modulating the composition ratio of IGZO film. These achievements represent a major advance toward implementation of full synaptic functionality in neuromorphic hardware and the strategy that combines the photonics and the electrics has great prospects in optoelectronic applications.

The development of van der Waals heterostructures in 2D materials systems has attracted considerable interests for exploring new insights of (opto‐) electrical characteristics, device physics, and novel functional applications. Utilizing organic molecular material with strong electron withdrawing ability, charge transfer van der Waals interfaces are formed between 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) and MoS2, via which the modulation of the onset voltages and optimization of subthreshold swing values in MoS2‐based field effect transistors are realized. Charge transfer process and its functionality mechanisms are further verified and investigated with first‐principles calculation, scanning Kelvin probe microscope characterization, and temperature‐dependent electrical characterization. With the charge transfer effect between reducing gas molecules and F4TCNQ, NH3 gas sensor is proposed and fabricated with the sensitivity reaching higher than 1000% at 100 ppm, much more outstanding performance than those of any reported MoS2‐based NH3 gas sensors. The F4TCNQ‐MoS2 hybrid strategy might open up a pathway for tuning and optimizing the electrical properties, in addition to novel functional units designing and fabrications in electric devices based on low‐dimensional semiconducting systems.

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In article number https://doi.org/10.1002/aelm.201800556, Hong Wang, Ling Li and co‐workers successfully emulate versatile functions of a biological synapse based on indium–gallium–zinc oxide (IGZO) thin film transistors through a new design by combining photonic and electric stimuli. Meanwhile, the synaptic functions can be mediated by modulating the composition ratio of IGZO film. The work contributes to the development of neuromorphic electronics and the combination of photonics and electric has great prospects in optoelectronic applications.

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The cuprate superconductors distinguish themselves from the conventional superconductors in that a small variation in the carrier doping can significantly change the superconducting transition temperature ( ), giving rise to a superconducting dome where a pseudogap 1,2 emerges in the underdoped region and a Fermi liquid appears in the overdoped region. Thus a systematic study of the properties over a wide doping range is critical for understanding the superconducting mechanism. Here, we report a new technique to continuously dope the surface of Bi 2 Sr 2 CaCu 2 O 8+x through an ozone/vacuum annealing method. Using in-situ ARPES, we obtain precise quantities of energy gaps and the coherent spectral weight over a wide range of doping. We discover that the d-wave component of the quasiparticle gap is linearly proportional to the Nernst temperature that is the onset of superconducting vortices 3 , strongly suggesting that the emergence of superconducting pairing is concomitant with the onset of free vortices, with direct implications for the onset of superconducting phase coherence at and the nature of the pseudogap phenomena.Bi 2 Sr 2 CaCu 2 O 8+x (Bi2212) single crystals have been extensively studied by angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy (STS) 4,5 , two of the major experimental techniques for probing the cuprates. However, high-quality Bi2212 crystals can be only obtained within a narrow doping range. Moreover, surface cleaving, necessary for surface techniques such as ARPES and STS, posses a serious problem for quantitative comparisons from sample to sample due to variation of surface conditions. Realizing that the doping level in this material is solely controlled by the excess oxygen concentration, we use ozone/vacuum annealing to continuously change the doping level of the surface layers, which are subsequently measured by in-situ ARPES (Figs. 1a-c).

In atomically-thin two-dimensional (2D) semiconductors, the nonuniformity in current flow due to its edge states may alter and even dictate the charge transport properties of the entire device. However, the influence of the edge states on electrical transport in 2D materials has not been sufficiently explored to date. Here, we systematically quantify the edge state contribution to electrical transport in monolayer MoS 2 /WSe 2 field-effect transistors, revealing that the charge transport at low temperature is dominated by the edge conduction with the nonlinear behavior. The metallic edge states are revealed by scanning probe microscopy, scanning Kelvin probe force microscopy and first-principle calculations. Further analyses demonstrate that the edge-state dominated nonlinear transport shows a universal power-law scaling relationship with both temperature and bias voltage, which can be well explained by the 1D Luttinger liquid theory. These findings demonstrate the Luttinger liquid behavior in 2D materials and offer important insights into designing 2D electronics.

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