Advances in neuromorphic computing:Expanding horizons for AI development through novel artificial neurons and in-sensor computing

AI development has brought great success to upgrading the information age.At the same time,the large-scale artificial neural network for building AI systems is thirsty for computing power,which is barely satisfied by the conventional computing hardware.In the post-Moore era,the increase in computing power brought about by the size reduction of CMOS in very large-scale integrated circuits(VLSIC)is challenging to meet the growing demand for AI computing power.To address the issue,technical approaches like neuromorphic computing attract great attention because of their feature of breaking Von-Neumann architecture,and dealing with AI algorithms much more parallelly and energy efficiently.Inspired by the human neural network architecture,neuromorphic computing hardware is brought to life based on novel artificial neurons constructed by new materials or devices.Although it is relatively difficult to deploy a training process in the neuromorphic architecture like spiking neural network(SNN),the development in this field has incubated promising technologies like in-sensor computing,which brings new opportunities for multidisciplinary research,including the field of optoelectronic materials and devices,artificial neural networks,and microelectronics integration technology.The vision chips based on the architectures could reduce unnecessary data transfer and realize fast and energy-efficient visual cognitive processing.This paper reviews firstly the architectures and algorithms of SNN,and artificial neuron devices supporting neuromorphic computing,then the recent progress of in-sensor computing vision chips,which all will promote the development of AI.

Control of GaN inverted pyramids growth on c-plane patterned sapphire substrates

Growth of gallium nitride(GaN)inverted pyramids on c-plane sapphire substrates is benefit for fabricating novel devices as it forms the semipolar facets.In this work,GaN inverted pyramids are directly grown on c-plane patterned sapphire substrates(PSS)by metal organic vapor phase epitaxy(MOVPE).The influences of growth conditions on the surface morphol-ogy are experimentally studied and explained by Wulff constructions.The competition of growth rate among{0001},{1011},and{1122}facets results in the various surface morphologies of GaN.A higher growth temperature of 985 ℃ and a lowerⅤ/Ⅲratio of 25 can expand the area of{}facets in GaN inverted pyramids.On the other hand,GaN inverted pyramids with almost pure{}facets are obtained by using a lower growth temperature of 930℃,a higherⅤ/Ⅲratio of 100,and PSS with pattern arrangement perpendicular to the substrate primary flat.

Gallium nitride blue laser diodes with pulsed current operation exceeding 15 W in optical output power

Since Shuji Nakamura first demonstrated the nitride laser in 1996[1],the domain of semiconductor laser technology has undergone a period of remarkable growth[2,3].Al In Ga N-based diode lasers(LDs)have proven their exceptional capabilities across a spectrum of pivotal applications,including high-density data storage,laser displays,laser lighting,and quantum technology[4].

Photonics-assisted THz wireless communication enabled by wide-bandwidth packaged backilluminated modified uni-traveling-carrier photodiode

This paper presents a wide-bandwidth back-illuminated modified uni-traveling-carrier photodiode(MUTC-PD)packaged with standard WR-5 rectangular waveguide for high-speed wireless communications.With optimized epitaxy structure and coplanar waveguide electrodes,the fabricated 4-μm-diameter PD exhibits ultra-flat frequency response and high saturation power.Integrated passive circuits including low-loss bias-tee and E-plane probe are designed to package the PD into a compact module with waveguide output.The packaged PD module has demonstrated a flat frequency response with fluctuations within±2.75 d B over a broadband of 140–220 GHz and a high saturated output power of-7.8 d Bm(166μW)at 140 GHz.For wireless communication applications,the packaged PD is used to implement 1-m free space transmission at carrier frequencies of 150.5 and 210.5 GHz,with transmission rates of 75 and 90 Gbps,respectively.

Studies on the nucleation of MBE grown Ⅲ-nitride nanowires on Si

GaN and AlN nanowires（NWs） have attracted great interests for the fabrication of novel nano-sized devices. In this paper, the nucleation processes of GaN and AlN NWs grown on Si substrates by molecular beam epitaxy（MBE）are investigated. It is found that GaN NWs nucleated on in-situ formed Si3N4 fully release the stress upon the interface between GaN NW and amorphous Si3N4 layer, while AlN NWs nucleated by aluminization process gradually release the stress during growth. Depending on the strain status as well as the migration ability of Ⅲ group adatoms, the different growth kinetics of GaN and AlN NWs result in different NW morphologies, i.e., GaN NWs with uniform radii and AlN NWs with tapered bases.

Study on Cognition of Urban Residents on Haze Control and Their Willingness to Pay:A Case Study of Zhengzhou City and Jiaozuo City

Residents’payment is an important supplement to the government’s urban haze control costs.In this paper,Zhengzhou City and Jiaozuo City of Henan Province were taken as research objects.Through research methods such as data mining,questionnaire survey and model construction,the residents’cognition on haze control,willingness to pay and its influencing factors were deeply studied.Main research results were as below:residents in Zhengzhou and Jiaozuo have improved their awareness and satisfaction with haze control,but the growth rate was slow.In 2014,2018 and 2021,the expected values of willingness to pay for haze control in Zhengzhou were 79.94,85.52 and 47.20 yuan/month respectively,while they were 62.17,57.77 and 46.96 yuan/month in Jiaozuo City.Residents’haze awareness had the most significant effect on the willingness to pay for haze control,and there was positive correlation(P<0.05).Residents’cognition of haze control was the most important factor affecting their willingness to pay for haze control.Residents’income level and air pollution level had a positive effect on residents’willingness to pay,while residents’confidence in the government had a weak impact on their willingness to pay.

Recommendations for Emergency Management of Rural Major Infectious Diseases in Non-epicenter Areas:Taking Village B during COVID-19 as an Example

This paper analyzed the key issues and challenges confronted in the governance of Village B in the non-epicenter area in rural areas of China during the COVID-19 pandemic.It clarified the weak points in the prevention and control of infectious diseases in Village B.A triple emergency management mechanism of"people-materials-environment"in rural areas should be established.It came up with constructive recommendations for scientifically and effectively responding to public health emergencies in rural non-epicenter areas,which is helpful to improve the rationality,legality and scientific effectiveness of the construction of emergency response mechanisms in rural areas.

Simulation model optimization for bonnet polishing considering consistent contact area response

Simulation model optimization plays a crucial role in the accurate prediction of material removal function in bonnet polishing processes,but model complexity often poses challenges to the practical implementation and efficiency of these processes.This paper presents an innovative method for optimizing simulation model parameters,focusing on achieving consistent contact area and the accurate prediction of the material removal function while preventing increase in model complexity.First,controllable and uncontrollable factors in bonnet simulations are analyzed,and then a simplified contact model is developed and applied under constant force conditions.To characterize the bonnet's contact performance,a contact area response curve is introduced,which can be obtained through a series of single spot contact experiments.Furthermore,a rubber hyperelastic parameter optimization model based on a neural network is proposed to achieve optimal matching of the contact area between simulation and experiment.The average deviation of the contact area under different conditions was reduced from 22.78%before optimization to 3.43%after optimization,preliminarily proving the effectiveness of the proposed simulation optimization model.Additionally,orthogonal experiments are further conducted to validate the proposed approach.The comparison between the experimental and predicted material removal functions reveals a high consistency,validating the accuracy and effectiveness of the proposed optimization method based on consistent contact response.This research provides valuable insights into enhancing the reliability and effectiveness of bonnet polishing simulations with a simple and practical approach while mitigating the complexity of the model.

Double-cliff-layer uni-traveling-carrier photodiode with high responsivity and ultra-broad bandwidth

A novel backside-illuminated double-cliff-layer uni-traveling-carrier(DCL-UTC)photodiode with both high responsivity and ultra-broad bandwidth is designed and demonstrated.A thick absorption layer is adopted for high responsivity,and a depletion region with double cliff layers is proposed to alleviate the space charge effect and maintain overshoot electron velocity under large photocurrents.In addition,inductive coplanar waveguide electrodes are employed to enhance the frequency response performance.The 6-μm-diameter photodiode exhibits a high responsivity of 0.51 A/W and a large 3-dB bandwidth of 102 GHz.A high RF output power of 2.7 dBm is recorded at 100 GHz.

面向柔性光电子器件的低温外延技术

柔性光电子器件需要在金属、玻璃、塑料等柔性非单晶衬底上制作或承载光电转换薄膜,已有的实现柔性光电子器件的方法分为两大类:直接在非单晶衬底上沉积有机光电转换薄膜;或者将外延生长的无机光电转换薄膜从单晶衬底转移到非单晶衬底.前者无法在柔性非单晶衬底上制作无机光电子器件,后者存在大面积转移的困难.如果能够在非单晶的柔性衬底上直接外延生长无机光电子器件,将为柔性无机光电子器件开辟一条新的技术路线和研究方向.传统的无机光电子器件的外延生长通常需要足够高的外延生长温度和耐高温的单晶衬底,前者裂解反应物并向其提供原子表面迁移能力,后者提供无机光电转换薄膜的晶格排列方式.通过电磁场耦合降低外延生长所需的温度,则有可能在柔性非单晶衬底上直接外延生长无机光电子薄膜.本文综合分析了国际上的低温外延技术的研究现状,并着重介绍了本研究团队提出的低温外延方法——电感应耦合等离子体金属有机物化学气相外延(inductive coupled plasma metal organic vapor phase epitaxy,ICP-MOVPE),包括ICP-MOVPE的设计思路、反应腔内等离子体的模拟仿真和该设备进行III族氮化物半导体外延生长的初步结果.

GaN基材料的低温外延技术

GaN基半导体材料的禁带宽度覆盖了整个可见光波段,且其具有优良的物理化学特性,因而被广泛应用于光电子器件、电力电子器件及射频微波器件的制备.传统的GaN基材料通常是利用金属有机物化学气相沉积、分子束外延或氢化物气相外延等在蓝宝石、硅或碳化硅等耐高温的单晶衬底上外延生长得到.这些外延生长技术通常采用高温来裂解参与反应的前驱体.随着信息化和智能化的变革不断深入,催生出了对核心光(电)子器件的低成本和柔性化等共性需求.廉价且易于大面积制备的非晶衬底(玻璃、塑料、金属、聚对苯二甲酸乙二醇酯(polyethylene terephthalate,PET)、聚二甲基硅氧烷(polydimethylsiloxane,PDMS)等)是较为理想的选择,但非晶衬底的一个显著缺点是不能耐受较高的生长温度.由此催生出了GaN基材料低温外延的需求,即需要一类在低温下可以利用外电场能量裂解反应前驱体的外延设备.到目前为止,人们基于物理气相沉积和化学气相沉积的基本原理已经开发出了多种低温外延技术,取得了初步的研究结果.本文分别对这两类低温外延技术进行详细介绍,包括设备结构、工作条件和相关的外延生长结果,总结各类技术的特点.最后,对低温外延技术的发展前景作了展望,指出未来研究需要关注的重点.

Wideband thin-film lithium niobate modulator with low half-wave-voltage length product

A novel thin-film lithium niobate(TFLN) electro-optic modulator is proposed and demonstrated. LiNbO_(3)-silica hybrid waveguide is adopted to maintain low optical loss for an electrode spacing as narrow as 3 μm, resulting in a low halfwave-voltage length product of only 1.7 V·cm. Capacitively loaded traveling-wave electrodes are employed to reduce the microwave loss, while a quartz substrate is used in place of a silicon substrate to achieve velocity matching. The fabricated TFLN modulator with a 5-mm-long modulation region exhibits a half-wave voltage of 3.4 V and a merely less than 2 d B roll-off in an electro-optic response up to 67 GHz.

Laser annealing of SiO2 film deposited by ICPECVD for fabrication of silicon based low loss waveguide

Laser annealing of silicon dioxide （SiO2） film formed by inductively coupled plasma enhanced chemical vapor deposition （ICPECVD）is studied for the fabrication of low loss silicon based waveguide. The influence of laser annealing on ICPECVD-deposited SiO2 film is investigated. The surface roughness, refractive index, and etch rate of annealed samples are compared with those of SiO2 film obtained by thermal oxidation. It is demonstrated that the performance of ICPECVD-deposited SiO2 film can be significantly improved by laser annealing. Al2O3/SIO2 waveguide has been fabricated on silicon substrate with the SiO2 lower cladding formed by ICPECVD and laser annealing process, and its propagation loss is found to be comparable with that of the waveguide with thermally oxidized lower cladding.

Size-dependent optical properties of InGaN quantum dots in GaN nanowires grown by MBE

Quantum dots in nanowires （DINWs） are considered as important building blocks for novel nanoscale semiconductor optoelectronic devices. In this paper, pure axial heterojunction InGaN/GaN DINWs are grown by using plasma-assisted molecular beam epitaxy （PA-MBE） system. The InGaN quantum dots （QDs） are disk-like observed by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The diameter of QDs can be controlled by the growth conditions of nanowires （NWs）, while the thickness of QDs can be controlled by the growth time of lnGaN. Temperature-dependent photoluminescence （TDPL） measurements demonstrate that the PL peak of DINWs with small and uniform sizes shows a general red shift with increasing temperature. However, the PL peak of D1NWs with non-uniform sizes shows an abnormal blue shift with increasing temperature, which is due to different internal quantum efficiencies of the DINWs with different sizes.

Simple dynamic energy core equivalent rays method to design freeform surface for extended source

A simple method is proposed to design free- form surface for Lambertian extended source. In this method, it can take advantage of the designing method for point source via substituting each incident ray with a dynamically calculated equivalent ray. For each facet on the freeform surface, the equivalent ray emits from the energy weighted average-emitting-position for the corre- sponding incident beam, and redirects into the direction which is determined by a source-to-target mapping. The results of the designing examples show that the light distributions＇ uniformities can be improved by this method, e.g., even the improvement of 59% can be achieved.