Artificial visual systems can recognize desired objects and information from complex environments, and are therefore highly desired for pattern recognition, object detection, and imaging applications. However, state-o...Artificial visual systems can recognize desired objects and information from complex environments, and are therefore highly desired for pattern recognition, object detection, and imaging applications. However, state-of-the-art artificial visual systems with high recognition performances that typically consist of electronic devices face the challenges of requiring huge storage space and high power consumption owing to redundant data. Here, we report a terahertz(THz) frequency-selective surface using a graphene split-ring resonator driven by ferroelectric polarization for efficient visual system applications. The downward polarization of the ferroelectric material offers an ultrahigh electrostatic field for doping p-type graphene with an anticipated Fermi level. By optimizing the geometric parameters of the devices and modulating the carrier behaviors of graphene, our plasmonic devices exhibit a tunable spectral response in a range of 1.7–6.0 THz with continuous transmission values. The alloptical neural network using graphene plasmonic surfaces designed in this study exhibited excellent performance in visual preprocessing and convolutional filtering and achieved an ultrahigh recognition accuracy of up to 99.3% in training the Modified National Institute of Standards and Technology(MNIST) handwritten digit dataset. These features demonstrate the great potential of graphene plasmonic devices for future smart artificial vision systems.展开更多
Self-powered photodetectors can convert light into electrical signals without external power input and are widely used in applications such as imaging,sensing,communication,and security.The most popular approach for c...Self-powered photodetectors can convert light into electrical signals without external power input and are widely used in applications such as imaging,sensing,communication,and security.The most popular approach for constructing a self-powered photodetector is typically based on the fabrication of an asymmetric metal-semiconductor(MS)contact;however,this technique is seriously limited by the Fermi-level pinning effect.Here,we report a room-temperature photodetector based on multi-layer MoS_(2) sandwiched between two separated asymmetric graphene contacts.Our photodetector was driven by the built-in electric field generated by a van der Waals(vd W)contact instead of the traditional MS contact.Operating under zero-bias voltage,the highest photoresponsivity of 0.63 AW^(-1) and a specific detectivity of 7.71×10^(12) Jones were achieved at a wavelength of 450 nm with 0.08μW cm^(-2) incident power intensity.Compared with devices using symmetric contacts,a high ON/OFF current ratio of approximately 1520 and a fast response time on the order of microseconds were also observed in our asymmetric graphene contact device.Our experimental results may open a novel way toward the realization of vd W contacts for the fabrication of selfpowered photodetectors.展开更多
基金supported by the National Natural Science Foundation of China(Grant No. 62201096)the Engineering Research Center of Digital Imaging and Display, Ministry of Education, Soochow University(Grant No. SDGC2246)the Open Project Program of Shanxi Key Laboratory of Advanced Semiconductor Optoelectronic Devices and Integrated Systems(Grant No. 2023SZKF12)。
文摘Artificial visual systems can recognize desired objects and information from complex environments, and are therefore highly desired for pattern recognition, object detection, and imaging applications. However, state-of-the-art artificial visual systems with high recognition performances that typically consist of electronic devices face the challenges of requiring huge storage space and high power consumption owing to redundant data. Here, we report a terahertz(THz) frequency-selective surface using a graphene split-ring resonator driven by ferroelectric polarization for efficient visual system applications. The downward polarization of the ferroelectric material offers an ultrahigh electrostatic field for doping p-type graphene with an anticipated Fermi level. By optimizing the geometric parameters of the devices and modulating the carrier behaviors of graphene, our plasmonic devices exhibit a tunable spectral response in a range of 1.7–6.0 THz with continuous transmission values. The alloptical neural network using graphene plasmonic surfaces designed in this study exhibited excellent performance in visual preprocessing and convolutional filtering and achieved an ultrahigh recognition accuracy of up to 99.3% in training the Modified National Institute of Standards and Technology(MNIST) handwritten digit dataset. These features demonstrate the great potential of graphene plasmonic devices for future smart artificial vision systems.
基金supported by the National Natural Science Foundation of China(Grant No.61971108)Science and Technology Foundation of Sichuan Province(Grant No.2021YFS0311)。
文摘Self-powered photodetectors can convert light into electrical signals without external power input and are widely used in applications such as imaging,sensing,communication,and security.The most popular approach for constructing a self-powered photodetector is typically based on the fabrication of an asymmetric metal-semiconductor(MS)contact;however,this technique is seriously limited by the Fermi-level pinning effect.Here,we report a room-temperature photodetector based on multi-layer MoS_(2) sandwiched between two separated asymmetric graphene contacts.Our photodetector was driven by the built-in electric field generated by a van der Waals(vd W)contact instead of the traditional MS contact.Operating under zero-bias voltage,the highest photoresponsivity of 0.63 AW^(-1) and a specific detectivity of 7.71×10^(12) Jones were achieved at a wavelength of 450 nm with 0.08μW cm^(-2) incident power intensity.Compared with devices using symmetric contacts,a high ON/OFF current ratio of approximately 1520 and a fast response time on the order of microseconds were also observed in our asymmetric graphene contact device.Our experimental results may open a novel way toward the realization of vd W contacts for the fabrication of selfpowered photodetectors.
