Constructing high-toughness polyimide binder with robust polarity and ion-conductive mechanisms ensuring long-term operational stability of silicon-based anodes

Silicon-based materials have demonstrated remarkable potential in high-energy-density batteries owing to their high theoretical capacity.However,the significant volume expansion of silicon seriously hinders its utilization as a lithium-ion anode.Herein,a functionalized high-toughness polyimide(PDMI) is synthesized by copolymerizing the 4,4'-Oxydiphthalic anhydride(ODPA) with 4,4'-oxydianiline(ODA),2,3-diaminobenzoic acid(DABA),and 1,3-bis(3-aminopropyl)-tetramethyl disiloxane(DMS).The combination of rigid benzene rings and flexible oxygen groups(-O-) in the PDMI molecular chain via a rigidness/softness coupling mechanism contributes to high toughness.The plentiful polar carboxyl(-COOH) groups establish robust bonding strength.Rapid ionic transport is achieved by incorporating the flexible siloxane segment(Si-O-Si),which imparts high molecular chain motility and augments free volume holes to facilitate lithium-ion transport(9.8 × 10^(-10) cm^(2) s^(-1) vs.16 × 10^(-10) cm^(2) s~(-1)).As expected,the SiO_x@PDMI-1.5 electrode delivers brilliant long-term cycle performance with a remarkable capacity retention of 85% over 500 cycles at 1.3 A g^(-1).The well-designed functionalized polyimide also significantly enhances the electrochemical properties of Si nanoparticles electrode.Meanwhile,the assembled SiO_x@PDMI-1.5/NCM811 full cell delivers a high retention of 80% after 100 cycles.The perspective of the binder design strategy based on polyimide modification delivers a novel path toward high-capacity electrodes for high-energy-density batteries.

Silicon-based optoelectronic heterogeneous integration for optical interconnection

The performance of optical interconnection has improved dramatically in recent years.Silicon-based optoelectronic heterogeneous integration is the key enabler to achieve high performance optical interconnection,which not only provides the optical gain which is absent from native Si substrates and enables complete photonic functionalities on chip,but also improves the system performance through advanced heterogeneous integrated packaging.This paper reviews recent progress of silicon-based optoelectronic heterogeneous integration in high performance optical interconnection.The research status,development trend and application of ultra-low loss optical waveguides,high-speed detectors,high-speed modulators,lasers and 2D,2.5D,3D and monolithic integration are focused on.

Regulating the Solvation Structure of Li^(+) Enables Chemical Prelithiation of Silicon-Based Anodes Toward High-Energy Lithium-Ion Batteries

The solvation structure of Li^(+) in chemical prelithiation reagent plays a key role in improving the low initial Coulombic efficiency(ICE) and poor cycle performance of silicon-based materials. Never theless, the chemical prelithiation agent is difficult to dope active Li^(+) in silicon-based anodes because of their low working voltage and sluggish Li^(+) diffusion rate. By selecting the lithium–arene complex reagent with 4-methylbiphenyl as an anion ligand and 2-methyltetrahydrofuran as a solvent, the as-prepared micro-sized Si O/C anode can achieve an ICE of nearly 100%. Interestingly, the best prelithium efficiency does not correspond to the lowest redox half-potential(E_(1/2)), and the prelithiation efficiency is determined by the specific influencing factors(E_(1/2), Li^(+) concentration, desolvation energy, and ion diffusion path). In addition, molecular dynamics simulations demonstrate that the ideal prelithiation efficiency can be achieved by choosing appropriate anion ligand and solvent to regulate the solvation structure of Li^(+). Furthermore, the positive effect of prelithiation on cycle performance has been verified by using an in-situ electrochemical dilatometry and solid electrolyte interphase film characterizations.

Research Towards Terahertz Power Amplifiers in Silicon-Based Process

In view of the existing design challenges for Terahertz(THz)power amplifiers(PAs),the common design methods and the efforts of the State Key Laboratory of Millimeter Wave,Southeast University,China in the development of silicon-based THz PAs,mainly including silicon-based PAs with operating frequencies covering 100–300 GHz,are summarized in this paper.Particularly,we design an LC-balun-based two-stage differential cascode PA with a center frequency of 150 GHz and an output power of 14 dBm.Based on a Marchand balun,we report a 220 GHz three-stage differential cascode PA with a saturated output power of 9.5 dBm.To further increase the output power of THz PA,based on a four-way differential power combining technique,we report a 211–263 GHz dual-LC-tank-based broadband PA with a recorded 14.7 dBm Psat and 16.4 dB peak gain.All the above circuits are designed in a standard 130 nm silicon germanium(SiGe)BiCMOS process.

Multifunctional silicon-based light emitting device in standard complementary metal oxide semiconductor technology

A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes： it can emit visible to near infra-red （NIR） light （the spectrum ranges from 500 nm to 1000 nm） in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light （the spectrum ranges from 900 nm to 1300 nm） in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.

Micro-Mechanism of Silicon-Based Waveguide Surface Smoothing in Hydrogen Annealing

The micro-mechanism of the silicon-based waveguide surface smoothing is investigated systematically to explore the effects of silicon-hydrogen bonds on high-temperature hydrogen annealing waveguides. The effect of silicon- hydrogen bonds on the surface migration movement of silicon atoms and the waveguide surface topography are revealed. The micro-migration from an upper state to a lower state of silicon atoms is driven by silicon- hydrogen bonding, which is the key to ameliorate the rough surface morphology of the silicon-based waveguide. The process of hydrogen annealing is experimentally validated based on the simulated parameters. The surface roughness declines from 1.523nm to 0.461 nm.

Design Technologies for Silicon-Based High-Efficiency RF Power Amplifiers:A Brief Overview

This paper presents a brief overview of several promising design technologies for high efficiency silicon-based radio frequency （RF） power amplifiers （PAs） as well as the use of these technologies in mobile broadband wireless communications. Four important aspects of PA design are addressed in this paper. First, we look at class-E PA design equations and provide an example of a class-E PA that achieves efficiency of 65-70% at 2.4 GHz. Then, we discuss state-of-the-art envelope tracking （ET） design for monolithic wideband RF mobile transmitter applications. A brief overview of Doherty PA design for the next-generation wireless handset applications is then given. Towards the end of the paper, we discuss an inherently broadband and highly efficient class-J PA design targeting future multi-band multi-standard wireless communication protocols.

Low insertion loss silicon-based spatial light modulator with high reflective materials outside Fabry–Perot cavity

The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth: their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.

High-performing silicon-based germanium Schottky photodetector with ITO transparent electrode

A near-infrared germanium(Ge)Schottky photodetector(PD)with an ultrathin silicon(Si)barrier enhancement layer between the indium-doped tin oxide(ITO)electrode and Ge epilayer on Si or silicon-on-insulator(SOI)is proposed and fabricated.The well-behaved ITO/Si cap/Ge Schottky junctions without intentional doping process for the Ge epilayer are formed on the Si and SOI substrates.The Si-and SOI-based ITO/Si cap/Ge Schottky PDs exhibit low dark current densities of 33 mA/cm2 and 44 mA/cm2,respectively.Benefited from the high transmissivity of ITO electrode and the reflectivity of SOI substrate,an optical responsivity of 0.19 A/W at 1550 nm wavelength is obtained for the SOI-based ITO/Si cap/Ge Schottky PD.These complementary metal–oxide–semiconductor(CMOS)compatible Si(or SOI)-based ITO/Si cap/Ge Schottky PDs are quite useful for detecting near-infrared wavelengths with high efficiency.

Comparison of commercial silicon-based anode materials for the design of a high-energy lithium-ion battery

Silicon(Si)is considered a potential alternative anode for next-generation Li-ion batteries owing to its high theoretical capacity and abundance.However,the commercial use of Si anodes is hindered by their large volume expansion(~300%).Numerous efforts have been made to address this issue.Among these efforts,Si-graphite co-utilization has attracted attention as a reasonable alternative for high-energy anodes.A comparative study of representative commercial Si-based materials,such as Si nanoparticles,Si suboxides,and Si−Graphite composites(SiGC),was conducted to characterize their overall performance in high-energy lithium-ion battery(LIB)design by incorporating conventional graphite.Nano-Si was found to exhibit poor electrochemical performance,with severe volume expansion during cycling.Si suboxide provided excellent cycling stability in a full-cell evaluation with stable volume variation after 50 cycles,but had a large irreversible capacity and remarkable volume expansion during the first cycle.SiGC displayed a good initial Coulombic efficiency and the lowest volume change in the first cycle owing to the uniformly distributed nano-Si layer on graphite;however,its long-term cycling stability was relatively poor.To complement each disadvantage of Si suboxide and SiGC,a new combination of these Si-based anodes was suggested and a reasonable improvement in overall battery performance was successfully achieved.

Silicon-based four-mode division multiplexing for chip-scale optical data transmission in the 2 μm waveband

Based on a silicon platform, we design and fabricate a four-mode division(de)multiplexer for chip-scale optical data transmission in the 2 μm waveband for the first time, to the best of our knowledge. The(de)multiplexer is composed of three tapered directional couplers for both mode multiplexing and demultiplexing processes. In the experiment, the average crosstalk for four channels is measured to be less than-18 dB over a wide wavelength range(70 nm) from 1950 to 2020 nm, and the insertion losses are also assessed. Moreover, we further demonstrate stable 5 Gbit/s direct modulation data transmission through the fabricated silicon photonic devices with nonreturn-to-zero on–off keying signals. The experimental results show clear eye diagrams, and the penalties at a bit error rate of 3.8 × 10-3 are all less than 2.5 dB after on-chip data transmission. The obtained results indicate that the presented silicon four-mode division multiplexer in the mid-infrared wavelength band might be a promising candidate facilitating chip-scale high-speed optical interconnects.

Influence of Al-doping on electroluminescence of silicon-based films

A series of Al-doped silicon-rich silica (AlSiO) composite films have been prepared by a dual ion beam co-sputtering method with a Al, Si and SiO2 composite target. The content of Al and Si in the films can be adjusted by changing the surface area of Al and Si of the target. Visible electroluminescence (EL) from the samples is found to have only one luminescence band peaked at 510 nm (2.4 eV). Experimental results show that the doping of Al is beneficial to reducing the onset voltage and to increasing the intensity of EL.

A Silicon-based Imidazolium Ionic Liquid Iodide Source for Dye-Sensitized Solar Cells

Room temperature molten salt 1-methyl-3-（trimethylsilyl）methyl-imidazolium iodide （MSII） was used for io-dide sources in dye-sensitized solar cells with an organic sensitizer 2-cyano-3-[5-[4-[3-[4-（4-（N,N-bis（4-methoxy-phenyl）amino）phenyl）phenyl]-2,5-di-n-butyl-pyrrolo[3,4-c]pyrrole-1,4-dione]phenyl] furan-2-yl] acrylic acid （DPP-I） as light harvester. With an optimized electrolyte （MSII ： I2 ： BI ： GuNCS=24 ： 2 ： 2 ： 0.4, BI and GuCNS are short for benzimidazole and guanidine thiocyanate, respectively）, photovoltaic parameters （Jsc, Voc, and ff） of device are 8.97 mA·cm^-2, 600 mV and 0.61, respectively, yielding a maximum overall photo-to-energy con-version efficiency （17） of 3.23%. And then the charge-transfer mechanism of devices was deeply analyzed with elec- trochemical impedance spectroscopy （EIS） in the dark.

Silicon-based optoelectronics for general-purpose matrix computation:a review

Conventional electronic processors,which are the mainstream and almost invincible hardware for computation,are approaching their limits in both computational power and energy efficiency,especially in large-scale matrix computation.By combining electronic,photonic,and optoelectronic devices and circuits together,silicon-based optoelectronic matrix computation has been demonstrating great capabilities and feasibilities.Matrix computation is one of the few general-purpose computations that have the potential to exceed the computation performance of digital logic circuits in energy efficiency,computational power,and latency.Moreover,electronic processors also suffer from the tremendous energy consumption of the digital transceiver circuits during high-capacity data interconnections.We review the recent progress in photonic matrix computation,including matrix-vector multiplication,convolution,and multiply–accumulate operations in artificial neural networks,quantum information processing,combinatorial optimization,and compressed sensing,with particular attention paid to energy consumption.We also summarize the advantages of siliconbased optoelectronic matrix computation in data interconnections and photonic-electronic integration over conventional optical computing processors.Looking toward the future of silicon-based optoelectronic matrix computations,we believe that silicon-based optoelectronics is a promising and comprehensive platform for disruptively improving general-purpose matrix computation performance in the post-Moore’s law era.

Electric field dependence of spin qubit in a Si-MOS quantum dot

Valley, the intrinsic feature of silicon, is an inescapable subject in silicon-based quantum computing. At the spin–valley hotspot, both Rabi frequency and state relaxation rate are significantly enhanced. With protection against charge noise, the valley degree of freedom is also conceived to encode a qubit to realize noise-resistant quantum computing.Here, based on the spin qubit composed of one or three electrons, we characterize the intrinsic properties of valley in an isotopically enriched silicon quantum dot(QD) device. For one-electron qubit, we measure two electric-dipole spin resonance(EDSR) signals which are attributed to partial occupation of two valley states. The resonance frequencies of two EDSR signals have opposite electric field dependences. Moreover, we characterize the electric field dependence of the upper valley state based on three-electron qubit experiments. The difference of electric field dependences of the two valleys is 52.02 MHz/V, which is beneficial for tuning qubit frequency to meet different experimental requirements. As an extension of electrical control spin qubits, the opposite electric field dependence is crucial for qubit addressability,individual single-qubit control and two-qubit gate approaches in scalable quantum computing.

Enhanced electrochemical performance of Si/C electrode through surface modification using SrF_(2) particle

The silicon-based material exhibits a high theoretical specific capacity and is one of the best anode for the next generation of advanced lithium-ion batteries(LIBs).However,it is difficult for the silicon-based anode to form a stable solid-state interphase(SEI)during Li alloy/de-alloy process due to the large volume change(up to 300%)between silicon and Li4.4Si,which seriously limits the cycle life of the LIBs.Herein,we use strontium fluoride(SrF_(2))particle to coat the silicon-carbon(Si/C)electrode(SrF_(2)@Si/C)to help forming a stable and high mechanical strength SEI by spontaneously embedding the SrF_(2) particle into SEI.Meanwhile the formed SEI can inhibit the volume expansion of the silicon-carbon anode during the cycle.The electrochemical test results show that the cycle performance and the ionic conductivity of the SrF_(2)@Si/C anode has been significantly improved.The X-ray photoelectron spectroscopy(XPS)analysis reveals that there are fewer electrolyte decomposition products formed on the surface of the SrF_(2)@Si/C anode.This study provides a facile approach to overcome the problems of Si/C electrode during the electrochemical cycling,which will be beneficial to the industrial application of silicon-based anode materials.

Si/Cu3_Si@C Composite Encapsulated in CNTs Network as High Performance Anode for Lithium Ion Batteries

Si/Cu3Si@C composites encapsulated in CNTs network(SCC-CNTs) were synthesized via the combination of ball-milling and CVD methods. SCC-CNTs consist of conductive Cu3Si, amorphous carbon layer, cross-linked CNTs, and the etched pores, which can play the synergistic effects on the improvement of electronic conductivity and Li^+ diffusion. The volume expansion of Si anode is also suppressed during the electrochemical process. The SCC-CNTs composites demonstrate a remarkably improved electrochemical performance compared with pure Si, which can deliver a discharge capacity of 2 171 mAh·g^-1 at 0.4 A·g^-1 with ICE of 85.2%, and retain 1197 mAh· g^-1 after 150 cycles. This work provides a facile approach to massively produce the high-performance Si-based anode materials for next-generation LIBs.

Silicon photonic transceivers for application in data centers

Global data traffic is growing rapidly,and the demand for optoelectronic transceivers applied in data centers(DCs)is also increasing correspondingly.In this review,we first briefly introduce the development of optoelectronics transceivers in DCs,as well as the advantages of silicon photonic chips fabricated by complementary metal oxide semiconductor process.We also summarize the research on the main components in silicon photonic transceivers.In particular,quantum dot lasers have shown great potential as light sources for silicon photonic integration—whether to adopt bonding method or monolithic integration—thanks to their unique advantages over the conventional quantum-well counterparts.Some of the solutions for highspeed optical interconnection in DCs are then discussed.Among them,wavelength division multiplexing and four-level pulseamplitude modulation have been widely studied and applied.At present,the application of coherent optical communication technology has moved from the backbone network,to the metro network,and then to DCs.

Effect of dark soliton on the spectral evolution of bright soliton in a silicon-on-insulator waveguide

The spectral evolution of bright soliton in a silicon-on-insulator optical waveguide is numerically simulated using the split-step Fourier method.The power and input chirp of the dark soliton and the second-order dispersion are varied to investigate the effect of dark soliton on the spectrum of bright soliton.The simulations prove that the dark soliton modifies the spectral shape of the bright soliton.Further,the variation in the power of dark soliton affects the splitting of bright soliton.Furthermore,the chirped dark soliton can improve the spectral width and flatness.The variation in the dispersion of dark soliton modifies the phase matching of the bright soliton and the dispersive wave emission,thereby affecting the spectral evolution.

Propagation characteristics of parallel dark solitons in silicon-on-insulator waveguide

The propagation characteristic of two identical and parallel dark solitons in a silicon-on-insulator(SOI)waveguide is simulated numerically using the split-step Fourier method.The parallel dark solitons imposed by the initial chirp are investigated mainly by changing their power,their relative time delay.The simulation shows that the time delay deforms the parallel dark soliton pulse,forming a bright-like soliton in the transmission process and making the transmission quality down.By increasing the power of one dark soliton,the energy of the other dark soliton can be increased,and larger increase in a soliton’s power leads to larger increase in the energy of the other.When the initial chirp is introduced into one of the dark solitons,higher energy consumption is observed.In particular,positive chirps resulting in pulse broadening width while negative chirps narrowing,with an obvious compression effect on the other dark soliton.Finally,large negative chirps are found to have a profound impact on parallel and nonparallel dark solitons.