Visible-light stimulated synaptic plasticity in amorphous indium−gallium−zinc oxide enabled by monocrystalline double perovskite for high-performance neuromorphic applications

Photoelectric synaptic devices have been considered as one of the key components in artificial neuromorphic systems due to their excellent capability to emulate the functions of visual neurons,such as light perception and image processing.Herein,we demonstrate an optically-stimulated artificial synapse with a clear photoresponse from ultraviolet to visible light,which is established on a novel heterostructure consisting of monocrystalline Cs2AgBiBr6 perovskite and indium–gallium–zinc oxide(IGZO)thin film.As compared with pure IGZO,the heterostructure significantly enhances the photoresponse and corresponding synaptic plasticity of the devices,which originate from the superior visible absorption of single-crystal Cs2AgBiBr6 and effective interfacial charge transfer from Cs2AgBiBr6 to IGZO.A variety of synaptic behaviors are realized on the fabricated thin-film transistors,including excitatory postsynaptic current,paired pulse facilitation,short-term,and long-term plasticity.Furthermore,an artificial neural network is simulated based on the photonic potentiation and electrical depression effects of synaptic devices,and an accuracy rate up to 83.8%±1.2%for pattern recognition is achieved.This finding promises a simple and efficient way to construct photoelectric synaptic devices with tunable spectrum for future neuromorphic applications.

Oxidation Resistance Coatings of Ir-Zr and Ir by Double Glow Plasma

Oxidation resistance coatings of Ire40 at.% Zr and Ir were produced onto Mo substrates by double glow plasma technology. The oxidation resistances of the coatings were evaluated at high temperature. Ire Zr coating consisted of two layers: the primary layer close to the substrate was composed of dense columnar grains and the second layer was composed of dense grains of nanometric size. The mass gain of Ir coating above 800 C was about 1.35% due to the formation of solid IrO2. The mass loss of Ir coating was about 5.3% due to the formation of gaseous oxide IrO3when being held at 1227 C for 30 min. The substrate was protected more effectively by multilayer than monolayer coating of Ir in oxidizing environment. The Ire Zr coating was well bonded to the substrate after oxidation at 800 C. After oxidation at 1000 C, the Ire Zr coating was poorly bonded to the substrate. The oxidation resistance of Ire Zr coating was poor due to high content of Zr.

Efficiently band-tailored type-Ⅲ van der Waals heterostructure for tunnel diodes and optoelectronic devices

Broken-gap(type-Ⅲ)two-dimensional(2D)van der Waals heterostructures(vdWHs)offer an ideal platform for interband tunneling devices due to their broken-gap band offset and sharp band edge.Here,we demonstrate an efficient control of energy band alignment in a typical type-ⅢvdWH,which is composed of vertically-stacked molybdenum telluride(MoTe2)and tin diselenide(SnSe2),via both electrostatic and optical modulation.By a single electrostatic gating with hexagonal boron nitride(hBN)as the dielectric,a variety of electrical transport characteristics including forward rectifying,Zener tunneling,and backward rectifying are realized on the same heterojunction at low gate voltages of±1 V.In particular,the heterostructure can function as an Esaki tunnel diode with a room-temperature negative differential resistance.This great tunability originates from the atomicallyflat and inert surface of h-BN that significantly suppresses the interfacial trap scattering and strain effects.Upon the illumination of an 885 nm laser,the band alignment of heterojunction can be further tuned to facilitate the direct tunneling of photogenerated charge carriers,which leads to a high photocurrent on/off ratio of>105 and a competitive photodetectivity of 1.03×1012 Jones at zero bias.Moreover,the open-circuit voltage of irradiated heterojunction can be switched from positive to negative at opposite gate voltages,revealing a transition from accumulation mode to depletion mode.Our findings not only promise a simple strategy to tailor the bands of type-ⅢvdWHs but also provide an in-depth understanding of interlayer tunneling for future low-power electronic and optoelectronic applications.