Neuromorphic computing has considerable potential in simulating the efficient information processing capabilities of the human brain. Implementing neuromorphic computing requires the development of artificial synaptic devices that mimic biological synapses, which are the basic for information processing, storage, and transmission in biological neural networks. Herein, we demonstrate a light-stimulated synaptic transistor (LSST) device based on graphene/hexagonal boron nitride (h-BN)/pentacene heterojunction for emulating the basic functions of the human brain. The LSST devices can detect light stimulus at a wavelength of 520 nm and exhibits a variety of typical synaptic properties, such as excitatory postsynaptic current, paired pulse facilitation, and transition from short-term memory to long-term memory. In addition, the LSST device is capable of simulating the learning and forgetting processes of the human brain. Based on the optically and electrically controlled conductivity modulation characteristics of the LSST device, we construct an artificial neural network for perform pattern recognition tasks, and recognition accuracy of handwritten digits is 88.5%. These results mean that our LSST devices have great potential for future applications in neuromorphic computing.
Influenced by the prominent progress of two-dimensional (2D) layered crystals, the fabrication of 2D nanostructures from non-layered materials has attracted more and more attention. Lead selenide (PbSe) is one of the superior candidate materials for photodetector with suitable bandgap and outstanding photoelectric properties. The growth and device preparation of PbSe supply great interest for the development of high-performance infrared photodetectors. Although a lot of efforts have been paid on preparing PbSe nanostructures for miniaturized detectors, it is challenging to synthesize excellent crystallinity and thin 2D PbSe nanosheets because of itsinherent rock salt nonlayered structure. In this work, we employ a catalyst-free facile physical vapor deposition (PVD) method for controllable synthesis of PbSe nanosheets by van der Waals epitaxy technology. By optimizing the growth temperature, PbSe nanosheets from triangular pyramid island to square 2D plane can be obtained. In addition, the 2D PbSe nanosheets detector has a responsivity of 3.03 A/W at the wavelength of 520 nm with the power density of 5.05 mW/cm2. This work provides a facile strategy to synthesize high-quality 2D PbSe nanosheets which have enormous potentials to fabricate high-performance miniaturized photodetector.
Due to the increasing demand for miniaturization and portability, the development of self-powered photodetectors that can work without external power supply has aroused great interest among researchers. As a group-10 layered transitional metal dichalcogenides, PtSe2 exhibits potential applications in photoelectric detection because of the unique properties such as high carrier mobility, tunable bandgap, and stability. However, its inherent large dark current hinders the further improvement of the performance of the PtSe2 photodetectors. In this paper, we fabricated a vertically aligned Two-dimensional (2D) van der Waals (vdWs) heterojunction composed of PtSe2 and MoSe2, which exhibits high sensitivity photoelectric detection performance in a wide band from visible light (405 nm) to near-infrared (1550 nm) without external bias. As a result, working in self-driving mode at room temperature, the responsivity and detectivity can reach 22.95 A W-1 and 9.27×1011 Jones with a fast response speed of 180/48 μs. This work is expected to provide a new idea for broadband, energy-efficient and high-performance miniaturized detectors.
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