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.

Comparative coherence between layered and traditional semiconductors: unique opportunities for heterogeneous integration

As Moore’s law deteriorates,the research and development of new materials system are crucial for transitioning into the post Moore era.Traditional semiconductor materials,such as silicon,have served as the cornerstone of modern technologies for over half a century.This has been due to extensive research and engineering on new techniques to continuously enrich silicon-based materials system and,subsequently,to develop better performed silicon-based devices.Meanwhile,in the emerging post Moore era,layered semiconductor materials,such as transition metal dichalcogenides(TMDs),have garnered considerable research interest due to their unique electronic and optoelectronic properties,which hold great promise for powering the new era of next generation electronics.As a result,techniques for engineering the properties of layered semiconductors have expanded the possibilities of layered semiconductor-based devices.However,there remain significant limitations in the synthesis and engineering of layered semiconductors,impeding the utilization of layered semiconductor-based devices for mass applications.As a practical alternative,heterogeneous integration between layered and traditional semiconductors provides valuable opportunities to combine the distinctive properties of layered semiconductors with well-developed traditional semiconductors materials system.Here,we provide an overview of the comparative coherence between layered and traditional semiconductors,starting with TMDs as the representation of layered semiconductors.We highlight the meaningful opportunities presented by the heterogeneous integration of layered semiconductors with traditional semiconductors,representing an optimal strategy poised to propel the emerging semiconductor research community and chip industry towards unprecedented advancements in the coming decades.

Heterogeneous integration of GaAs pHEMT and Si CMOS on the same chip

In this work,we demonstrate the technology of wafer-scale transistor-level heterogeneous integration of Ga As pseudomorphic high electron mobility transistors（p HEMTs） and Si complementary metal–oxide semiconductor（CMOS） on the same Silicon substrate.Ga As p HEMTs are vertical stacked at the top of the Si CMOS wafer using a wafer bonding technique,and the best alignment accuracy of 5 μm is obtained.As a circuit example,a wide band Ga As digital controlled switch is fabricated,which features the technologies of a digital control circuit in Si CMOS and a switch circuit in Ga As p HEMT,15% smaller than the area of normal Ga As and Si CMOS circuits.

Heterogeneous integration of InP HEMTs on quartz wafer using BCB bonding technology

Heterogeneous integrated InP high electron mobility transistors(HEMTs)on quartz wafers are fabricated successfully by using a reverse-grown InP epitaxial structure and benzocyclobutene(BCB)bonding technology.The channel of the new device is In_(0.7)Ga_(0.3)As,and the gate length is 100 nm.A maximum extrinsic transconductance gm,max of 855.5 mS/mm and a maximum drain current of 536.5 mA/mm are obtained.The current gain cutoff frequency is as high as 262 GHz and the maximum oscillation frequency reaches 288 GHz.In addition,a small signal equivalent circuit model of heterogeneous integration of InP HEMTs on quartz wafer is built to characterize device performance.

Heterogeneous integration of GaSb layer on(100)Si substrate by ion-slicing technique

Integration of the high-quality Ga Sb layer on an Si substrate is significant to improve the Ga Sb application in optoelectronic integration.In this work,a suitable ion implantation fluence of 5×10^(16)-cm^(-2)H ions for Ga Sb layer transfer is confirmed.Combining the strain change and the defect evolution,the blistering and exfoliation processes of Ga Sb during annealing is revealed in detail.With the direct wafer bonding,the Ga Sb layer is successfully transferred onto a(100)Si substrate covered by 500-nm thickness thermal oxide SiO_(2)layer.After being annealed at 200℃,the Ga Sb layer shows high crystalline quality with only 77 arcsec for the full width at half maximum(FWHM)of the x-ray rocking curve(XRC).

Engineering applications and technical challenges of active array microsystems

In the post-Moore era,the development of active phased array antennas will inevitably trend towards active array microsystems.In this paper,the characteristics and composition of the active array antenna are briefly described.Owing to the high efficiency,low profile,and light weight of the active array microsystems,the application prospects and advantages in the engineering of multi-functional airborne radar,spaceborne radar,and communication systems are analyzed.Moreover,according to the characteristics of the post-Moore era of integrated circuits,scientific and technological problems in the active array microsystems are presented,including multi-scale,multi-signal,and multi-physics field coupling.The challenges are also discussed,such as new architectures and algorithms,miniaturization of passive components,novel materials and processes,ultra-wideband technology,and new interdisciplinary technological applications.This paper is expected to inspire in-depth research on active array microsystems.

Manufacturability and mechanical reliability study for heterogeneous integration system in display(HiSID)

In this paper,the system on display panel(SoDP)architecture,the primary stage of heterogeneous integration system in display(HiSID),is introduced for the first time.In this architecture,the driving components of display,which are supposed to be on the display flexible print circuit(FPC)in traditional architecture,are innovatively integrated onto the backside of display panel.Through the SoDP architecture,the simulated impact strain in the panel fan-out region can decrease about 30%compared to the traditional architecture,and SoDP provides more the 10 mm extra space in the in-plane Y-direction for holding a larger battery.Also,the SoDP is compatible with the current organic laser emitted diode(OLED)and system in package(SiP)processes.Besides the primary stage,this paper also presents a comprehensive and extensive analysis on the challenges of the manufacturability for the advanced stage of HiSID from four key technologies perspectives:device miniaturization,massive manufacturing,driving technology,and advanced heterogeneous integration.

A novel computational method for protein-protein interaction networks prediction of alpha-synuclein

Alpha-synuclein plays an important role in Parkinson's disease(PD).The current study of alpha-synuclein mainly concentrates at the gene level.However, it is found that the study at the protein level has special significance.Meanwhile, there is free information on the Internet, such as databases and algorithms of protein-protein interactions(PPIs).In this paper, a novel method which integrates distributed heterogeneous data sources and algorithms to predict PPIs for alpha-synuclein in silico is proposed.The PPIs generated by the method take advantage of various experimental data, and indicate new information about PPIs for alpha-synuclein.In the end of this paper, the result illustrates that the method is practical.It is hoped that the prediction result obtained by this method can provide guidance for biological experiments of PPIs for alpha-synuclein to reveal possible mechanisms of PD.

Green Air-Ground Integrated Heterogeneous Network in 6G Era

The research of three-dimensional integrated communication technology plays a key role in achieving the ubiquitous connectivity,ultra-high data rates,and emergency communications in the sixth generation(6G)networks.Aerial networking provides a prom⁃ising solution to flexible,scalable,low-cost and reliable coverage for wireless devices.The integration of aerial network and terrestrial network has been an inevitable paradigm in the 6G era.However,energy-efficient communications and networking among aerial net⁃work and terrestrial network face great challenges.This paper is dedicated to discussing green communications of the air-ground integrated heterogeneous network(AGIHN).We first provide a brief introduction to the characteristics of AGIHN in 6G networks.Further,we analyze the challenges of green AGIHN from the aspects of green terrestrial networks and green aerial networks.Finally,several solutions to and key technologies of the green AGIHN are discussed.

Non-cooperative game for network access selection in heterogeneous integrated networks

The integration of different heterogeneous access networks is one of the remarkable characteristics of the next generation network,in which users with multi-network interface terminals can independently select access network to obtain the most desired service.A kind of unified quantification model of non-monotone quality of service(QoS) and a model of non-cooperative game between users and networks are proposed for heterogeneous network access selection.An optimal network pricing mechanism could be formulated by using a novel strategy which is used in this non-cooperative game model to balance the interests of both the users and the networks.This access network selection mechanism could select the most suitable network for users,and it also could provide the basis when formulating QoS standards in heterogeneous integrated networks.The simulation results show that this network selection decision-making algorithm can meet the users' demand for different levels service in different scenes and it can also avoid network congestion caused by unbalanced load.

Efficient thermal dissipation in wafer-scale heterogeneous integration of single-crystalline𝛽β-Ga_(2)O_(3)thin film on SiC

The semiconductor,β-Ga_(2)O_(3)is attractive for applications in high power electronic devices with low conduction loss due to its ultra-wide bandgap(∼4.9 eV)and large Baliga’s figure of merit.However,the thermal conductivity of𝛽β-Ga_(2)O_(3)is much lower than that of other wide/ultra-wide bandgap semiconductors,such as SiC and GaN,which results in the deterioration of𝛽β-Ga_(2)O_(3)-based device performance and reliability due to self-heating.To overcome this problem,a scalable thermal management strategy was proposed by heterogeneously integrating wafer-scale single-crystalline𝛽β-Ga_(2)O_(3)thin films on a highly thermally conductive SiC substrate.Characterization of the transferred𝛽β-Ga_(2)O_(3)thin film indicated a uniform thickness to within±2.01%,a smooth surface with a roughness of 0.2 nm,and good crystalline quality with an X-ray rocking curves(XRC)full width at half maximum of 80 arcsec.Transient thermoreflectance measurements were employed to investigate the thermal properties.The thermal performance of the fabricated𝛽β-Ga_(2)O_(3)/SiC heterostructure was effectively improved in comparison with that of the𝛽β-Ga_(2)O_(3)bulk wafer,and the effective thermal boundary resistance could be further reduced to 7.5 m 2 K/GW by a post-annealing process.Schottky barrier diodes(SBDs)were fabricated on both a𝛽β-Ga_(2)O_(3)/SiC heterostructured material and a𝛽β-Ga_(2)O_(3)bulk wafer.Infrared thermal imaging revealed the temperature increase of the SBDs on𝛽β-Ga_(2)O_(3)/SiC to be one quarter that on the𝛽β-Ga_(2)O_(3)bulk wafer with the same applied power,which suggests that the combination of the𝛽-Ga_(2)O_(3)thin film and SiC substrate with high thermal conductivity promotes heat dissipation in𝛽β-Ga_(2)O_(3)-based devices.

Organic electro-optic polymer materials and organic-based hybrid electro-optic modulators

High performance electro-optic modulator,as the key device of integrated ultra-wideband optical systems,have be-come the focus of research.Meanwhile,the organic-based hybrid electro-optic modulators,which make full use of the advant-ages of organic electro-optic(OEO)materials(e.g.high electro-optic coefficient,fast response speed,high bandwidth,easy pro-cessing/integration and low cost)have attracted considerable attention.In this paper,we introduce a series of high-perform-ance OEO materials that exhibit good properties in electro-optic activity and thermal stability.In addition,the recent progress of organic-based hybrid electro-optic devices is reviewed,including photonic crystal-organic hybrid(PCOH),silicon-organic hy-brid(SOH)and plasmonic-organic hybrid(POH)modulators.A high-performance integrated optical platform based on OEO ma-terials is a promising solution for growing high speeds and low power consumption in compact sizes.

Joint Design of Clustering and In-cluster Data Route for Heterogeneous Wireless Sensor Networks

A heterogeneous wireless sensor network comprises a number of inexpensive energy constrained wireless sensor nodes which collect data from the sensing environment and transmit them toward the improved cluster head in a coordinated way. Employing clustering techniques in such networks can achieve balanced energy consumption of member nodes and prolong the network lifetimes.In classical clustering techniques, clustering and in-cluster data routes are usually separated into independent operations. Although separate considerations of these two issues simplify the system design, it is often the non-optimal lifetime expectancy for wireless sensor networks. This paper proposes an integral framework that integrates these two correlated items in an interactive entirety. For that,we develop the clustering problems using nonlinear programming. Evolution process of clustering is provided in simulations. Results show that our joint-design proposal reaches the near optimal match between member nodes and cluster heads.

Two-dimensional optoelectronic devices for silicon photonic integration

With the unprecedented increasing demand for extremely fast processing speed and huge data capacity,traditional silicon-based information technology is becoming saturated due to the encountered bottle-necks of Moore's Law.New material systems and new device architectures are considered promising strategies for this challenge.Two-dimensional(2D)materials are layered materials and garnered persistent attention in recent years owing to their advantages in ultrathin body,strong light-matter interaction,flexible integration,and ultrabroad operation wavelength range.To this end,the integra-tion of 2D materials into silicon-based platforms opens a new path for silicon photonic integration.In this work,a comprehensive review is given of the recent signs of progress related to 2D material inte-grated optoelectronic devices and their potential applications in silicon photonics.Firstly,the basic op-tical properties of 2D materials and heterostructures are summarized in the first part.Then,the state-of-the-art three typical 2D optoelectronic devices for silicon photonic applications are reviewed in detail.Finally,the perspective and challenges for the aim of 3D monolithic heterogeneous integration of these 2D optoelectronic devices are discussed.

An Electromagnetic Perspective of Artificial Intelligence Neuromorphic Chips

The emergence of artificial intelligence has represented great potential in solving a wide range of complex problems.However,traditional general-purpose chips based on von Neumann architectures face the“memory wall”problem when applied in artificial intelligence applications.Based on the efficiency of the human brain,many intelligent neuromorphic chips have been proposed to emulate its working mechanism and neuron-synapse structure.With the emergence of spiking-based neuromorphic chips,the computation and energy efficiency of such devices could be enhanced by integrating a variety of features inspired by the biological brain.Aligning with the rapid development of neuromorphic chips,it is of great importance to quickly initiate the investigation of the electromagnetic interference and signal integrity issues related to neuromorphic chips for both CMOS-based and memristor-based artificial intelligence integrated circuits.Here,this paper provides a review of neuromorphic circuit design and algorithms in terms of electromagnetic issues and opportunities with a focus on signal integrity issues,modeling,and optimization.Moreover,the heterogeneous structures of neuromorphic circuits and other circuits,such as memory arrays and sensors using different integration technologies,are also reviewed,and locations where signal integrity might be compromised are discussed.Finally,we provide future trends in electromagnetic interference and signal integrity and outline prospects for upcoming neuromorphic devices.

Integrated heterogeneous silicon/Ⅲ –Ⅴ mode-locked lasers

The mode-locked laser diode has emerged as a promising candidate as a signal source for photonic radar systems,wireless data transmission, and frequency comb spectroscopy. They have the advantages of small size, low cost,high reliability, and low power consumption, thanks to semiconductor technology. Mode-locked lasers based on silicon photonics advance these qualities by the use of highly advanced silicon manufacturing technology. This paper will begin by giving an overview of mode-locked laser diode literature, and then focus on mode-locked lasers on silicon. The dependence of mode-locked laser performance on design details is presented.

Inkjet printing technology for increasing the I/O density of 3D TSV interposers

Interposers with through-silicon vias(TSVs)play a key role in the three-dimensional integration and packaging of integrated circuits and microelectromechanical systems.In the current practice of fabricating interposers,solder balls are placed next to the vias;however,this approach requires a large foot print for the input/output(I/O)connections.Therefore,in this study,we investigate the possibility of placing the solder balls directly on top of the vias,thereby enabling a smaller pitch between the solder balls and an increased density of the I/O connections.To reach this goal,inkjet printing(that is,piezo and super inkjet)was used to successfully fill and planarize hollow metal TSVs with a dielectric polymer.The under bump metallization(UBM)pads were also successfully printed with inkjet technology on top of the polymer-filled vias,using either Ag or Au inks.The reliability of the TSV interposers was investigated by a temperature cycling stress test(−40℃ to+125℃).The stress test showed no impact on DC resistance of the TSVs;however,shrinkage and delamination of the polymer was observed,along with some micro-cracks in the UBM pads.For proof of concept,SnAgCu-based solder balls were jetted on the UBM pads.

Advances of semiconductor mode-locked laser for optical frequency comb generation

Semiconductor mode-locked lasers(MLLs)can provide coherent optical frequency combs(OFCs)with high repetition rates and output power,which have been recognized as potential multi-wavelength sources used in optical communication field due to their compactness,high-efficiency,and low-cost properties.In this article,we have reviewed recent development of semiconductor MLL-based frequency comb generation.Different approaches of semiconductor MLLs for OFC generation are synoptically summarized based on various material platforms.The representative progress of III-V semiconductor MLLs on III-V platform and especially on Si substrates is both discussed for the applications in integrated silicon photonics.

Two-dimensional materials in photonic integrated circuits:recent developments and future perspectives[Invited]

The heterogeneous integration of photonic integrated circuits(PICs)with a diverse range of optoelectronic materials has emerged as a transformative approach,propelling photonic chips toward larger scales,superior performance,and advanced integration levels.Notably,two-dimensional(2D)materials,such as graphene,transition metal dichalcogenides(TMDCs),black phosphorus(BP),and hexagonal boron nitride(hBN),exhibit remarkable device performance and integration capabilities,offering promising potential for large-scale implementation in PICs.In this paper,we first present a comprehensive review of recent progress,systematically categorizing the integration of photonic circuits with 2D materials based on their types while also emphasizing their unique advantages.Then,we discuss the integration approaches of 2D materials with PICs.We also summarize the technical challenges in the heterogeneous integration of 2D materials in photonics and envision their immense potential for future applications in PICs.

Integrating MEMS and ICs

The majority of microelectromechanical system(MEMS)devices must be combined with integrated circuits(ICs)for operation in larger electronic systems.While MEMS transducers sense or control physical,optical or chemical quantities,ICs typically provide functionalities related to the signals of these transducers,such as analog-to-digital conversion,amplification,filtering and information processing as well as communication between the MEMS transducer and the outside world.Thus,the vast majority of commercial MEMS products,such as accelerometers,gyroscopes and micro-mirror arrays,are integrated and packaged together with ICs.There are a variety of possible methods of integrating and packaging MEMS and IC components,and the technology of choice strongly depends on the device,the field of application and the commercial requirements.In this review paper,traditional as well as innovative and emerging approaches to MEMS and IC integration are reviewed.These include approaches based on the hybrid integration of multiple chips(multi-chip solutions)as well as system-on-chip solutions based on wafer-level monolithic integration and heterogeneous integration techniques.These are important technological building blocks for the‘More-Than-Moore’paradigm described in the International Technology Roadmap for Semiconductors.In this paper,the various approaches are categorized in a coherent manner,their merits are discussed,and suitable application areas and implementations are critically investigated.The implications of the different MEMS and IC integration approaches for packaging,testing and final system costs are reviewed.