Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds...Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds to laser pulse and high-voltage signal while the metal coil generates an oscillating voltage pulseenvelope signal. The generation of this oscillating signal is not related to the input bias voltage of the PCSS, the pulsecircuit components, or the electrode structure of the PCSS, rather it is related to the output characteristic of the PCSS.This physical phenomenon can be explained using the current surge model in photoconducting antenna. Preparingohmic contact electrode on the silicon carbide material forms the PCSS, which generates a large number ofphotogenerated carriers when ultra-fast laser pulses irradiate the surface of the material and Simultaneously applies abias voltage signal between the electrode. At this time inside the PCSS the electric field causes the transient current,radiating electromagnetic wave to the metal coil to generate oscillating signal.展开更多
Integrated circuits(ICs)are the foundation of information technology development.The optimal design scheme of an analog IC is determined by iteratively running the simulation software and comparing the performance met...Integrated circuits(ICs)are the foundation of information technology development.The optimal design scheme of an analog IC is determined by iteratively running the simulation software and comparing the performance metrics.However,the simulation software of an analog IC is time-consuming,which leads to the low design efficiency.Due to the nonideal factors in analog ICs,the nonlinear relationship between design parameters and performance metrics cannot be well described by the deduced approximation equations.Inspired by the image and semantic recognition,a universal high-efficiency modeling method for analog ICs based on convolutional neural network(CNN)was proposed in the current work,named as CNN-IC.The sparse topology mapping method was proposed to map the design parameters into a sparse matrix,which includes the spatial and transistor characteristics of analog IC.The CNN model with three convolutional kernels was constructed to extract“transistor-circuit module-integrate circuit”features level by level,which can replace the simulation software to effectively improve the training efficiency and accuracy.Two typical analog ICs were selected to verify the effectiveness of the CNN-IC model.The results show that the accuracy of the CNN-IC model could reach over 99%and that its convergence rate was the fastest compared with the machine learning models in the state of the art.展开更多
Enhancement-mode(E-mode)GaN-on-Si radio-frequency(RF)high-electron-mobility transistors(HEMTs)were fabri-cated on an ultrathin-barrier(UTB)AlGaN(<6 nm)/GaN heterostructure featuring a naturally depleted 2-D electro...Enhancement-mode(E-mode)GaN-on-Si radio-frequency(RF)high-electron-mobility transistors(HEMTs)were fabri-cated on an ultrathin-barrier(UTB)AlGaN(<6 nm)/GaN heterostructure featuring a naturally depleted 2-D electron gas(2DEG)channel.The fabricated E-mode HEMTs exhibit a relatively high threshold voltage(VTH)of+1.1 V with good uniformity.A maxi-mum current/power gain cut-off frequency(fT/fMAX)of 31.3/99.6 GHz with a power added efficiency(PAE)of 52.47%and an out-put power density(Pout)of 1.0 W/mm at 3.5 GHz were achieved on the fabricated E-mode HEMTs with 1-μm gate and Au-free ohmic contact.展开更多
Perovskite materials,with their outstanding optoelectronic properties,low cost,solution‐processability,and scalability,haveemerged as promising candidates in the field of sensors.Despite extensive exploration into th...Perovskite materials,with their outstanding optoelectronic properties,low cost,solution‐processability,and scalability,haveemerged as promising candidates in the field of sensors.Despite extensive exploration into the photoelectric properties andtraditional applications(e.g.,gas sensing)of perovskite sensors,there has been limited focus on the fabrication processes thatdominate their performance and emerging application directions.The flourishing development of perovskite sensors shouldcomprehend the challenges in fabrication processes(e.g.,stability,uniformity,and scale‐up production)of perovskite sensorsand further improve the sensing performance in conjunction with the working principles,extending their application fields.Herein,a comprehensive overview primarily focuses on the significant challenges faced by perovskite sensors in emergingapplication fields,including performance enhancement and process optimization.The key performance parameters andworking principles of perovskite sensor are analyzed first.Then we review the effective design strategies and solutions proposedin recent research,while providing insights into optimizing sensor design to enhance sensing performance for precise detection.Moreover,some emerging applications of perovskite sensors,such as smart biomedical diagnosis,wearable devices,andartificial intelligence,are explored.Current challenges and future trends are also addressed,emphasizing the growing potentialof perovskite sensors in advancing sensor technology innovation and interdisciplinary applications.展开更多
Ultrasonic imaging technology has advanced rapidly,the escalating demand for imaging quality has driven the continuous development of ultrasonic transducers featuring high-performance.Among them,the crucial factors co...Ultrasonic imaging technology has advanced rapidly,the escalating demand for imaging quality has driven the continuous development of ultrasonic transducers featuring high-performance.Among them,the crucial factors constraining the further enhancement of imaging quality are the frequency of the device and the intensity of the echo signal.Piezoelectric composites have become a hotspot for ultrasonic transducers and imaging applications due to their excellent properties.However,due to the limitations of the accuracy of the cutting process,the development of piezoelectric/polymer composites is often undermined by undesirable pseudo-vibrations,especially in high-frequency applications,which will significantly reduce energy conversion efficiency.In this study,a novel design method of 1e3 piezoelectric composites with gradient nanoparticle doped polymer is proposed to eliminate the undesired lateral vibrations.Based on the optimized composites,a high-performance composite ultrasonic transducer with a center frequency of 8.51 MHz is prepared.Compared with the traditional composite transducer,the optimized transducer improves the echo voltage amplitude significantly,reaching nearly 3 times.The above advantages are further verified in high-quality ultrasound and photoacoustic imaging.The optimization method has valuable guidance for the design of high-frequency composite transducers,which have great potential in ultrasonic and photoacoustic imaging applications.展开更多
基金supported by Major Projects of Shanxi Province (202101030201001)。
文摘Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered anew phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here thePCSS responds to laser pulse and high-voltage signal while the metal coil generates an oscillating voltage pulseenvelope signal. The generation of this oscillating signal is not related to the input bias voltage of the PCSS, the pulsecircuit components, or the electrode structure of the PCSS, rather it is related to the output characteristic of the PCSS.This physical phenomenon can be explained using the current surge model in photoconducting antenna. Preparingohmic contact electrode on the silicon carbide material forms the PCSS, which generates a large number ofphotogenerated carriers when ultra-fast laser pulses irradiate the surface of the material and Simultaneously applies abias voltage signal between the electrode. At this time inside the PCSS the electric field causes the transient current,radiating electromagnetic wave to the metal coil to generate oscillating signal.
基金supported by the Xidian University Specially Funded Project for Interdisciplinary Exploration(No:TZJH2024049)the National Natural Science Foundation of China of China(No:62090043,61934006)the National Key Research and Development Program of China(No:2022YFB4401300).
文摘Integrated circuits(ICs)are the foundation of information technology development.The optimal design scheme of an analog IC is determined by iteratively running the simulation software and comparing the performance metrics.However,the simulation software of an analog IC is time-consuming,which leads to the low design efficiency.Due to the nonideal factors in analog ICs,the nonlinear relationship between design parameters and performance metrics cannot be well described by the deduced approximation equations.Inspired by the image and semantic recognition,a universal high-efficiency modeling method for analog ICs based on convolutional neural network(CNN)was proposed in the current work,named as CNN-IC.The sparse topology mapping method was proposed to map the design parameters into a sparse matrix,which includes the spatial and transistor characteristics of analog IC.The CNN model with three convolutional kernels was constructed to extract“transistor-circuit module-integrate circuit”features level by level,which can replace the simulation software to effectively improve the training efficiency and accuracy.Two typical analog ICs were selected to verify the effectiveness of the CNN-IC model.The results show that the accuracy of the CNN-IC model could reach over 99%and that its convergence rate was the fastest compared with the machine learning models in the state of the art.
基金supported in part by the National Key Research and Development Program of China under Grant 2022YFB3604400in part by the Youth Innovation Promotion Association of Chinese Academy Sciences(CAS)+4 种基金in part by CAS-Croucher Funding Scheme under Grant CAS22801in part by National Natural Science Foundation of China under Grant 62074161,Grant 62004213,and Grant U20A20208in part by the Beijing Municipal Science and Technology Commission project under Grant Z201100008420009 and Grant Z211100007921018in part by the University of CASin part by IMECAS-HKUST-Joint Laboratory of Microelectronics.
文摘Enhancement-mode(E-mode)GaN-on-Si radio-frequency(RF)high-electron-mobility transistors(HEMTs)were fabri-cated on an ultrathin-barrier(UTB)AlGaN(<6 nm)/GaN heterostructure featuring a naturally depleted 2-D electron gas(2DEG)channel.The fabricated E-mode HEMTs exhibit a relatively high threshold voltage(VTH)of+1.1 V with good uniformity.A maxi-mum current/power gain cut-off frequency(fT/fMAX)of 31.3/99.6 GHz with a power added efficiency(PAE)of 52.47%and an out-put power density(Pout)of 1.0 W/mm at 3.5 GHz were achieved on the fabricated E-mode HEMTs with 1-μm gate and Au-free ohmic contact.
基金supported by the National Key Research and Development Program of China(2021YFA0715600,2021YFA0717700)the NationalNatural Science Foundation of China(22308268,22478318,62274127,62374128).
文摘Perovskite materials,with their outstanding optoelectronic properties,low cost,solution‐processability,and scalability,haveemerged as promising candidates in the field of sensors.Despite extensive exploration into the photoelectric properties andtraditional applications(e.g.,gas sensing)of perovskite sensors,there has been limited focus on the fabrication processes thatdominate their performance and emerging application directions.The flourishing development of perovskite sensors shouldcomprehend the challenges in fabrication processes(e.g.,stability,uniformity,and scale‐up production)of perovskite sensorsand further improve the sensing performance in conjunction with the working principles,extending their application fields.Herein,a comprehensive overview primarily focuses on the significant challenges faced by perovskite sensors in emergingapplication fields,including performance enhancement and process optimization.The key performance parameters andworking principles of perovskite sensor are analyzed first.Then we review the effective design strategies and solutions proposedin recent research,while providing insights into optimizing sensor design to enhance sensing performance for precise detection.Moreover,some emerging applications of perovskite sensors,such as smart biomedical diagnosis,wearable devices,andartificial intelligence,are explored.Current challenges and future trends are also addressed,emphasizing the growing potentialof perovskite sensors in advancing sensor technology innovation and interdisciplinary applications.
基金supported by the National Natural Science Foundations of China(No.62304165)the Fundamental Research Funds for the Central Universities(No.ZYTS25224,ZYTS25214)+4 种基金the China postdoctoral science foundation(No.2023M732745,No.2024T170691)Shaanxi Province Postdoctoral Scientific Research Project Grant(No.30102230001)Macao Young Scholars Program of the China postdoctoral science foundation(No.AM2024013)the Natural Science Foundation of Liaoning Province-Joint Open Fund of State Key Laboratory of Robotics(No.2022-KF-22-03)Natural Science Fundamental Research Project of Shaanxi Province of China(No.2023-JC-QN-0709).
文摘Ultrasonic imaging technology has advanced rapidly,the escalating demand for imaging quality has driven the continuous development of ultrasonic transducers featuring high-performance.Among them,the crucial factors constraining the further enhancement of imaging quality are the frequency of the device and the intensity of the echo signal.Piezoelectric composites have become a hotspot for ultrasonic transducers and imaging applications due to their excellent properties.However,due to the limitations of the accuracy of the cutting process,the development of piezoelectric/polymer composites is often undermined by undesirable pseudo-vibrations,especially in high-frequency applications,which will significantly reduce energy conversion efficiency.In this study,a novel design method of 1e3 piezoelectric composites with gradient nanoparticle doped polymer is proposed to eliminate the undesired lateral vibrations.Based on the optimized composites,a high-performance composite ultrasonic transducer with a center frequency of 8.51 MHz is prepared.Compared with the traditional composite transducer,the optimized transducer improves the echo voltage amplitude significantly,reaching nearly 3 times.The above advantages are further verified in high-quality ultrasound and photoacoustic imaging.The optimization method has valuable guidance for the design of high-frequency composite transducers,which have great potential in ultrasonic and photoacoustic imaging applications.
