In the past few decades,numerous high-performance silicon(Si)photonic devices have been demonstrated.Si,as a photonic platform,has received renewed interest in recent years.Efficient Si-basedⅢ–Ⅴquantum-dot(QDs)lase...In the past few decades,numerous high-performance silicon(Si)photonic devices have been demonstrated.Si,as a photonic platform,has received renewed interest in recent years.Efficient Si-basedⅢ–Ⅴquantum-dot(QDs)lasers have long been a goal for semiconductor scientists because of the incomparable optical properties of Ⅲ–Ⅴcompounds.Although the material dissimilarity betweenⅢ–Ⅴmaterial and Si hindered the development of monolithic integrations for over 30 years,considerable breakthroughs happened in the 2000s.In this paper,we review recent progress in the epitaxial growth of various Ⅲ–ⅤQD lasers on both offcut Si substrate and on-axis Si(001)substrate.In addition,the fundamental challenges in monolithic growth will be explained together with the superior characteristics of QDs.展开更多
The Ta Q alleles as one of the AP2-like transcription factors in common wheat(Triticum aestivum) play an important role in the evolution of spike characteristics from wild and domesticated emmer to modern wheat cultiv...The Ta Q alleles as one of the AP2-like transcription factors in common wheat(Triticum aestivum) play an important role in the evolution of spike characteristics from wild and domesticated emmer to modern wheat cultivars. Its loss-of-function mutant not only changed threshability and spike architecture but also affected plant height, flowering time, and floret structure. However, the comprehensive functions of Ta AQ and Ta Dq genes in wheat have not been fully elucidated yet. Here, CRISPR/Sp Cas9 was used to edit wheat Ta AQ and Ta Dq. We obtained homozygous plants in the T1 generation with loss of function of only Ta AQ or Ta Dq and simultaneous loss of function of Ta AQ and Ta Dq to analyze the effect of these genes on wheat spikes and floret shapes. The results demonstrated that the Ta AQ-edited plants and the Ta AQ and Ta Dq simultaneously-edited plants were nearly similar in spike architecture, whereas the Ta Dq-edited plants were different from the wild-type ones only in plant height. Moreover, the Ta AQ-edited plants or the Ta AQ and Ta Dq simultaneously-edited plants were more brittle than the wild-type and the Ta Dqedited plants. Based on the expression profiling, we postulated that the VRN1, FUL2, SEP2, SEP5, and SEP6 genes might affect the number of spikelets and florets per spike in wheat by regulating the expression of Ta Q. Combining the results of this report and previous reports, we conceived a regulatory network of wheat traits, including plant height, spike shape, and floral organs, which were influenced by AP2-like family genes. The results achieved in this study will help us to understand the regulating mechanisms of Ta AQ and Ta Dq alleles on wheat floral organs and inflorescence development.展开更多
Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–...Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys,synthesized by a simple and controllable chemical solution deposition method,are reported.The graded bandgaps,arising from the spatial grading of Se composition and thickness within a single domain,are tuned from 1.83 to 1.73 eV,leading to the formation of a homojunction with a builtin electric field.Consequently,a strong and sensitive gate-modulated photovoltaic effect is demonstrated,enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1,a specific detectivity up to^10^11 Jones,and an on/off ratio up to^10^4.Remarkably,when illuminated by the lights ranging from 405 to 808 nm,the biased devices yield a champion photoresponsivity of 191.5 A W−1,a specific detectivity up to^1012 Jones,a photoconductive gain of 10^6–10^7,and a photoresponsive time in the order of^50 ms.These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.展开更多
Over the past decades, the progress in the growth of materials which can be applied to cutting-edge technologies in the field of electronics, optoelectronics and energy harvesting has been remarkable. Among the variou...Over the past decades, the progress in the growth of materials which can be applied to cutting-edge technologies in the field of electronics, optoelectronics and energy harvesting has been remarkable. Among the various materials, group Ⅲ–Ⅴ semiconductors are of particular interest and have been widely investigated due to their excellent optical properties and high carrier mobility. However, the integration of Ⅲ–Ⅴ structures as light sources and numerous other optical components on Si,which is the foundation for most optoelectronic and electronic integrated circuits, has been hindered by the large lattice mismatch between these compounds. This mismatch results in substantial amounts of strain and degradation of the performance of the devices. Nanowires(NWs) are unique nanostructures that induce elastic strain relaxation, allowing for the monolithic integration of Ⅲ–Ⅴ semiconductors on the cheap and mature Si platform. A technique that ensures flexibility and freedom in the design of NW structures is the growth of ternary Ⅲ–Ⅴ NWs, which offer a tuneable frame of optical characteristics, merely by adjusting their nominal composition. In this review, we will focus on the recent progress in the growth of ternary Ⅲ–Ⅴ NWs on Si substrates. After analysing the growth mechanisms that are being employed and describing the effect of strain in the NW growth, we will thoroughly inspect the available literature and present the growth methods, characterization and optical measurements of each of the Ⅲ–Ⅴ ternary alloys that have been demonstrated. The different properties and special treatments required for each of these material platforms are also discussed. Moreover, we will present the results from the works on device fabrication, including lasers, solar cells, water splitting devices, photodetectors and FETs, where ternary Ⅲ–Ⅴ NWs were used as building blocks. Through the current paper, we exhibit the up-to-date state in this field of research and summarize the important accomplishments of the past few years.展开更多
Species closely related to wheat are important genetic resources for agricultural production,functional genomics studies and wheat improvement.In this study,a wheat gene related to regeneration,TaWOX5,was applied to e...Species closely related to wheat are important genetic resources for agricultural production,functional genomics studies and wheat improvement.In this study,a wheat gene related to regeneration,TaWOX5,was applied to establish the Agrobacterium-mediated transformation systems of Triticum monococcum,hexaploid triticale,and rye(Secale cereale L.)using their immature embryos.Transgenic plants were efficiently generated.During the transformation process,the Agrobacterium infection efficiency was assessed by histochemical staining forβ-glucuronidase(GUS).Finally,the transgenic nature of regenerated plants was verified by polymerase chain reaction(PCR)-based genotyping for the presence of the GUS and bialaphos resistance(bar)genes,histochemical staining for GUS protein,and the QuickStix strip assay for bar protein.The transformation efficiency of T.monococcum genotype PI428182 was 94.4%;the efficiencies of four hexaploid triticale genotypes Lin456,ZS3297,ZS1257,and ZS3224 were 52.1,41.2,19.4,and 16.0%,respectively;and the transformation efficiency of rye cultivar Lanzhou Heimai was 7.8%.Fluorescence in situ hybridization(FISH)and genomic in situ hybridization(GISH)analyses indicated that the GUS transgenes were integrated into the distal or near centromere(proximal)regions of the chromosomes in transgenic T.monococcum and hexaploid triticale plants.In the transgenic hexaploid triticale plants,the foreign DNA fragment was randomly integrated into the AABB and RR genomes.Furthermore,the transgene was almost stably inherited in the next generation by Mendel’s law.The findings in this study will promote the genetic improvement of the three plant species for grain or forage production and the improvement of cereal species including wheat for functional genomics studies.展开更多
The research in silicon photonics has been booming due to its potential for lowcost,reliable,energy-efficient and high-density chip-wise integration using widely available CMOS technology,featuring the tremendous succ...The research in silicon photonics has been booming due to its potential for lowcost,reliable,energy-efficient and high-density chip-wise integration using widely available CMOS technology,featuring the tremendous success in modulator,detector and other passive waveguide components in industry.However,the absence of efficient and reliable electrical to optical converter on Si platform has been considered as“the last piece of the puzzle”,hindered by the in-direct bandgap property of Si bulk materials.CompoundⅢ–Ⅴsemiconductor devices offer highly efficient optical light emitting sources and optical amplifiers,hence the compound semiconductor materials and devices on Si platform are drawing more and more attention nowadays as it could make possible the long-dreamed light sources on Si substrates by combining their advantages with silicon ICs,enabling the fabrication of full functional optoelectronic circuits,chip-to-chip and even system-to-system optical chips.展开更多
[Objectives]To use liquid chromatography-mass spectrometry technology to analyze the chemical composition of traditional Chinese medicine and explore its application in the evaluation of quality stability of tradition...[Objectives]To use liquid chromatography-mass spectrometry technology to analyze the chemical composition of traditional Chinese medicine and explore its application in the evaluation of quality stability of traditional Chinese medicine.[Methods]Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-QTOF-MS)was used to detect the samples of Moluodan concentrated pills.By comparing and analyzing the detection results of 10 different batches of Moluodan concentrated pills,combined with principal component analysis(PCA),the quality stability of Moluodan concentrated pills was evaluated.[Results]A total of 367 chemical components were identified in Moluodan concentrated pills.The average repetition rate of the chemical components contained in the 10 different batches of samples reached 92%.The overall quality stability of the Moluodan concentrated pills was good.[Conclusions]The UPLC-QTOF-MS technology combined with PCA provides a reference for the overall quality evaluation of Moluodan concentrated pills,and provides new detection methods and ideas for the analysis of the components of Chinese medicine.展开更多
Broad-spectrum resistance(BSR)is highly sought after for the effective management of crop diseases.However,genes suitable for developing BSR remain scarce.In this study,we demonstrate the development of BSR to wheat y...Broad-spectrum resistance(BSR)is highly sought after for the effective management of crop diseases.However,genes suitable for developing BSR remain scarce.In this study,we demonstrate the development of BSR to wheat yellow rust(YR),powdery mildew(PM),and leaf rust(LR)diseases elicited by three biotrophic fungal pathogens using a newly defined module,namely,RFEL1-NPR3.RFEL1 is an active RING-finger E3 ubiquitin ligase identified in diploid and polyploid wheat species,which ubiquitinates and promotes the degradation of wheat NPR3(TaNPR3),an important negative immune regulator conserved in higher plants,via the 26S proteasome system.Downregulation of TaNPR3 by either overexpressing RFEL1 or knocking out TaNPR3 confers strong resistance against four different YR races as well as the PM and LR diseases without adverse effects on wheat growth and yield traits.Notably,the enhanced disease resistance exhibited by RFEL1-overexpressing and TaNPR3-knockout lines is correlated with increased expression of defense related genes and elevated stability of NPR1,a pivotal positive regulator of plant immune signaling.Our findings underscore the importance of ubiquitination-dependent NPR3 degradation in plant immunity and advocate for the application of the RFEL1-NPR3 module in engineering BSR against biotrophic fungal pathogens in wheat and other crops.展开更多
Robust laser sources are a fundamental building block for contemporary information technologies.Originating from condensed-matter physics,the concept of topology has recently entered the realm of optics,offering funda...Robust laser sources are a fundamental building block for contemporary information technologies.Originating from condensed-matter physics,the concept of topology has recently entered the realm of optics,offering fundamentally new design principles for lasers with enhanced robustness.In analogy to the well-known Majorana fermions in topological superconductors,Dirac-vortex states have recently been investigated in passive photonic systems and are now considered as a promising candidate for robust lasers.Here,we experimentally realize the topological Diracvortex microcavity lasers in InAs/InGaAs quantum-dot materials monolithically grown on a silicon substrate.We observe room-temperature continuous-wave linearly polarized vertical laser emission at a telecom wavelength.We confirm that the wavelength of the Dirac-vortex laser is topologically robust against variations in the cavity size,and its free spectral range defies the universal inverse scaling law with the cavity size.These lasers will play an important role in CMOS-compatible photonic and optoelectronic systems on a chip.展开更多
A reliable,efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics.Despite the impressive advances that have be...A reliable,efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics.Despite the impressive advances that have been made in developing 1.3-μm Si-based quantum dot(QD)lasers,extending the wavelength window to the widely used 1.55-μm telecommunication region remains difficult.In this study,we develop a novel photonic integration method of epitaxial growth of III-V on a wafer-scale InP-on-Si(100)(InPOS)heterogeneous substrate fabricated by the ion-cutting technique to realize integrated lasers on Si substrate.This ion-cutting plus epitaxial growth approach decouples the correlated root causes of many detrimental dislocations during heteroepitaxial growth,namely lattice and domain mismatches.Using this approach,we achieved state-of-the-art performance of the electrically-pumped,continuouswave(CW)1.55-μm Si-based laser with a room-temperature threshold current density of 0.65 kA/cm^(-2),and output power exceeding 155mW per facet without facet coating in CW mode.CW lasing at 120℃ and pulsed lasing at over 130℃ were achieved.This generic approach is also applied to other material systems to provide better performance and more functionalities for photonics and microelectronics.展开更多
We report low-noise, high-performance single transverse mode 1.3 μm InAs/GaAs quantum dot lasers monolithically grown on silicon(Si) using molecular beam epitaxy. The fabricated narrow-ridge-waveguide Fabry–Perot(FP...We report low-noise, high-performance single transverse mode 1.3 μm InAs/GaAs quantum dot lasers monolithically grown on silicon(Si) using molecular beam epitaxy. The fabricated narrow-ridge-waveguide Fabry–Perot(FP) lasers have achieved a room-temperature continuous-wave(CW) threshold current of 12.5 mA and high CW temperature tolerance up to 90°C. An ultra-low relative intensity noise of less than-150 dB∕Hz is measured in the 4–16 GHz range. Using this low-noise Si-based laser, we then demonstrate 25.6 Gb/s data transmission over13.5 km SMF-28. These low-cost FP laser devices are promising candidates to provide cost-effective solutions for use in uncooled Si photonics transmitters in inter/hyper data centers and metropolitan data links.展开更多
Monolithic integration of Ⅲ-Ⅴ lasers with small footprint, good coherence, and low power consumption based on a CMOS-compatible Si substrate have been known as an efficient route towards high-density optical interco...Monolithic integration of Ⅲ-Ⅴ lasers with small footprint, good coherence, and low power consumption based on a CMOS-compatible Si substrate have been known as an efficient route towards high-density optical interconnects in the photonic integrated circuits. However, the material dissimilarities between Si and Ⅲ-Ⅴ materials limit the performance of monolithic microlasers. Here, under the pumping condition of a continuous-wave 632.8 nm He–Ne gas laser at room temperature, we achieved an InAs/GaAs quantum dot photonic crystal bandedge laser, which is directly grown on an on-axis Si(001) substrate, which provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform.展开更多
We report on the first electrically pumped continuous-wave(CW) In As/Ga As quantum dot(QD) laser grown on Si with a GaInP upper cladding layer. A QD laser structure with a Ga_(0.51)In_(0.49)P upper cladding layer and ...We report on the first electrically pumped continuous-wave(CW) In As/Ga As quantum dot(QD) laser grown on Si with a GaInP upper cladding layer. A QD laser structure with a Ga_(0.51)In_(0.49)P upper cladding layer and an Al_(0.53)Ga_(0.47)As lower cladding layer was directly grown on Si by metal–organic chemical vapor deposition. It demonstrates the postgrowth annealing effect on the QDs was relieved enough with the GaInP upper cladding layer grown at a low temperature of 550°C. Broad-stripe edge-emitting lasers with 2-mm cavity length and 15-μm stripe width were fabricated and characterized. Under CW operation, room-temperature lasing at ~1.3 μm has been achieved with a threshold density of 737 A∕cm^2 and a single-facet output power of 21.8 mW.展开更多
Multifunctional devices are of great interest for integration and miniaturization on the same platform, but simple addition of functionalities would lead to excessively large devices. Here, the photodetection and chem...Multifunctional devices are of great interest for integration and miniaturization on the same platform, but simple addition of functionalities would lead to excessively large devices. Here, the photodetection and chemical sensing device is developed based on two-dimensional(2D) glassygraphene that meets similar property requirements for the two functionalities. An appropriate bandgap arising from the distorted lattice structure enables glassy graphene to exhibit comparable or even improved photodetection and chemical sensing capability, compared with pristine graphene. Due to strong interactions between glassy graphene and the ambient atmosphere, the devices are less sensitive to photoinduced desorption than the ones based on graphene. Consequently,the few-layer glassy graphene device delivers positive photoresponse, with a responsivity of 0.22 A W^(-1) and specific detectivity reaching ~10^(10) Jones under 405 nm illumination.Moreover, the intrinsic defects and strain in glassy graphene can enhance the adsorption of analytes, leading to high chemical sensing performance. Specifically, the extracted signalto-noise-ratio of the glassy graphene device for detecting acetone is 48, representing more than 50% improvement over the device based on graphene. Additionally, bias-voltage-and thickness-dependent volatile organic compound(VOC) sensing features are identified, indicating the few-layer glassy graphene is more sensitive. This study successfully demonstrates the potential of glassy graphene for integrated photodetection and chemical sensing, providing a promising solution for multifunctional applications further beyond.展开更多
Continuous room temperature nanowire lasing from silicon-integrated optoelectronic elements requires careful optimisation of both the lasing cavity Q-factor and population inversion conditions.We apply time-gated opti...Continuous room temperature nanowire lasing from silicon-integrated optoelectronic elements requires careful optimisation of both the lasing cavity Q-factor and population inversion conditions.We apply time-gated optical interferometry to the lasing emission from high-quality GaAsP/GaAs quantum well nanowire laser structures,revealing high Q-factors of 1250±90 corresponding to end-facet reflectivities of R=0.73±0.02.By using optimised direct-indirect band alignment in the active region,we demonstrate a well-refilling mechanism providing a quasifour-level system leading to multi-nanosecond lasing and record low room temperature lasing thresholds(~6μJ cm^(−2) pulse−1)for Ⅲ-Ⅴ nanowire lasers.Our findings demonstrate a highly promising new route towards continuously operating silicon-integrated nanolaser elements.展开更多
Semiconductor mode-locked lasers(MLLs)are promising frequency comb sources for dense wavelength-divisionmultiplexing(DWDM)data communications.Practical data communication requires a frequency-stable comb source in a t...Semiconductor mode-locked lasers(MLLs)are promising frequency comb sources for dense wavelength-divisionmultiplexing(DWDM)data communications.Practical data communication requires a frequency-stable comb source in a temperature-varying environment and a minimum tone spacing of 25 GHz to support high-speed DWDM transmissions.To the best of our knowledge,however,to date,there have been no demonstrations of comb sources that simultaneously offer a high repetition rate and stable mode spacing over an ultrawide temperature range.Here,we report a frequency comb source based on a quantum dot(QD)MLL that generates a frequency comb with stable mode spacing over an ultrabroad temperature range of 20–120℃.The two-section passively mode-locked In As QD MLL comb source produces an ultra-stable fundamental repetition rate of 25.5 GHz(corresponding to a 25.5 GHz spacing between adjacent tones in the frequency domain)with a variation of 0.07 GHz in the tone spacing over the tested temperature range.By keeping the saturable absorber reversely biased at-2 V,stable mode-locking over the whole temperature range can be achieved by tuning the current of the gain section only,providing easy control of the device.At an elevated temperature of 100℃,the device shows a 6 d B comb bandwidth of 4.81 nm and 31 tones with>36 d B optical signal-to-noise ratio.The corresponding relative intensity noise,averaged between 0.5 GHz and 10 GHz,is-146 d Bc∕Hz.Our results show the viability of the In As QD MLLs as ultra-stable,uncooled frequency comb sources for low-cost,large-bandwidth,and low-energy-consumption optical data communications.展开更多
The rapid development of emerging technologies observed in recent years,such as artificial intelligence, machine learning, mobile internet, big data,cloud computing, and the Internet of Everything, are generating esca...The rapid development of emerging technologies observed in recent years,such as artificial intelligence, machine learning, mobile internet, big data,cloud computing, and the Internet of Everything, are generating escalatingdemands for expanding the capacity density, and speed in next-generation opticalcommunications. This poses a significant challenge to existing communicationtechniques. Within this context, the integration of near-infraredbroadband, tunable, and high-gain luminescent materials into silicon opticalcircuits or fiber architectures to transmit and modulate light shows enormouspotential for advancing next-generation communication techniques. Here, thisreview provides an overview of the recent breakthroughs in near-infrared luminescentepitaxial/colloidal quantum dots, and metal-active-center-doped materialsfor broadband optical amplifiers and tunable lasers. We also expound onefforts to enhance the bandwidth and gain of these materials-based amplifiersand lasers, exploring the challenges associate with developing ultra-broadbandand high-speed optical communication systems. Additionally, the potentialapplications in Fifth Generation Fixed Networks, integration with 5G and 6Gwireless networks, compensation for current Si electronic based CMOS forhigh computing capability, and the prospects of these light sources for nextgenerationoptoelectronic devices are discussed.展开更多
基金financial support from the UK EPSRC under grant No. EP/P006973/1the EPSRC National Epitaxy Facility European project H2020-ICT-PICTURE (780930)+2 种基金the Royal Academy of Engineering (RF201617/16/28)Investissments d’avenir (IRT Nanoelec: ANR-10-IRT-05 and Need for IoT: ANR-15-IDEX-02)the Chinese Scholarship Council for funding
文摘In the past few decades,numerous high-performance silicon(Si)photonic devices have been demonstrated.Si,as a photonic platform,has received renewed interest in recent years.Efficient Si-basedⅢ–Ⅴquantum-dot(QDs)lasers have long been a goal for semiconductor scientists because of the incomparable optical properties of Ⅲ–Ⅴcompounds.Although the material dissimilarity betweenⅢ–Ⅴmaterial and Si hindered the development of monolithic integrations for over 30 years,considerable breakthroughs happened in the 2000s.In this paper,we review recent progress in the epitaxial growth of various Ⅲ–ⅤQD lasers on both offcut Si substrate and on-axis Si(001)substrate.In addition,the fundamental challenges in monolithic growth will be explained together with the superior characteristics of QDs.
基金financially supported in part by grants from the Ministry of Agriculture and Rural Affairs of China(2016ZX08009001 and 2016ZX08010004)the Science and Technology Department of Ningxia China(2019BBF02020)the Chinese Academy of Agricultural Sciences(2060302-2-19)。
文摘The Ta Q alleles as one of the AP2-like transcription factors in common wheat(Triticum aestivum) play an important role in the evolution of spike characteristics from wild and domesticated emmer to modern wheat cultivars. Its loss-of-function mutant not only changed threshability and spike architecture but also affected plant height, flowering time, and floret structure. However, the comprehensive functions of Ta AQ and Ta Dq genes in wheat have not been fully elucidated yet. Here, CRISPR/Sp Cas9 was used to edit wheat Ta AQ and Ta Dq. We obtained homozygous plants in the T1 generation with loss of function of only Ta AQ or Ta Dq and simultaneous loss of function of Ta AQ and Ta Dq to analyze the effect of these genes on wheat spikes and floret shapes. The results demonstrated that the Ta AQ-edited plants and the Ta AQ and Ta Dq simultaneously-edited plants were nearly similar in spike architecture, whereas the Ta Dq-edited plants were different from the wild-type ones only in plant height. Moreover, the Ta AQ-edited plants or the Ta AQ and Ta Dq simultaneously-edited plants were more brittle than the wild-type and the Ta Dqedited plants. Based on the expression profiling, we postulated that the VRN1, FUL2, SEP2, SEP5, and SEP6 genes might affect the number of spikelets and florets per spike in wheat by regulating the expression of Ta Q. Combining the results of this report and previous reports, we conceived a regulatory network of wheat traits, including plant height, spike shape, and floral organs, which were influenced by AP2-like family genes. The results achieved in this study will help us to understand the regulating mechanisms of Ta AQ and Ta Dq alleles on wheat floral organs and inflorescence development.
基金supported by Grants from the UK EPSRC Future Compound Semiconductor Manufacturing Hub(EP/P006973/1)the financial support from EPSRC(EP/L018330/1,EP/N032888/1)+3 种基金the U.S.Army Research Laboratory under Cooperative Agreement Number W911NF-16-2-0120the “973 Program—the National Basic Research Program of China” Special Funds for the Chief Young Scientis(2015CB358600)the Excellent Young Scholar Fund from National Natural Science Foundation of China(21422103)the China Scholarship Council(CSC)
文摘Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys,synthesized by a simple and controllable chemical solution deposition method,are reported.The graded bandgaps,arising from the spatial grading of Se composition and thickness within a single domain,are tuned from 1.83 to 1.73 eV,leading to the formation of a homojunction with a builtin electric field.Consequently,a strong and sensitive gate-modulated photovoltaic effect is demonstrated,enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1,a specific detectivity up to^10^11 Jones,and an on/off ratio up to^10^4.Remarkably,when illuminated by the lights ranging from 405 to 808 nm,the biased devices yield a champion photoresponsivity of 191.5 A W−1,a specific detectivity up to^1012 Jones,a photoconductive gain of 10^6–10^7,and a photoresponsive time in the order of^50 ms.These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.
基金funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721394
文摘Over the past decades, the progress in the growth of materials which can be applied to cutting-edge technologies in the field of electronics, optoelectronics and energy harvesting has been remarkable. Among the various materials, group Ⅲ–Ⅴ semiconductors are of particular interest and have been widely investigated due to their excellent optical properties and high carrier mobility. However, the integration of Ⅲ–Ⅴ structures as light sources and numerous other optical components on Si,which is the foundation for most optoelectronic and electronic integrated circuits, has been hindered by the large lattice mismatch between these compounds. This mismatch results in substantial amounts of strain and degradation of the performance of the devices. Nanowires(NWs) are unique nanostructures that induce elastic strain relaxation, allowing for the monolithic integration of Ⅲ–Ⅴ semiconductors on the cheap and mature Si platform. A technique that ensures flexibility and freedom in the design of NW structures is the growth of ternary Ⅲ–Ⅴ NWs, which offer a tuneable frame of optical characteristics, merely by adjusting their nominal composition. In this review, we will focus on the recent progress in the growth of ternary Ⅲ–Ⅴ NWs on Si substrates. After analysing the growth mechanisms that are being employed and describing the effect of strain in the NW growth, we will thoroughly inspect the available literature and present the growth methods, characterization and optical measurements of each of the Ⅲ–Ⅴ ternary alloys that have been demonstrated. The different properties and special treatments required for each of these material platforms are also discussed. Moreover, we will present the results from the works on device fabrication, including lasers, solar cells, water splitting devices, photodetectors and FETs, where ternary Ⅲ–Ⅴ NWs were used as building blocks. Through the current paper, we exhibit the up-to-date state in this field of research and summarize the important accomplishments of the past few years.
基金supported by grants from the National Natural Science Foundation of China (31971946)the Technology Innovation Program of the Chinese Academy of Agricultural Sciences, China (2060302-2-23 and ASTIP-2060302-2-19).
文摘Species closely related to wheat are important genetic resources for agricultural production,functional genomics studies and wheat improvement.In this study,a wheat gene related to regeneration,TaWOX5,was applied to establish the Agrobacterium-mediated transformation systems of Triticum monococcum,hexaploid triticale,and rye(Secale cereale L.)using their immature embryos.Transgenic plants were efficiently generated.During the transformation process,the Agrobacterium infection efficiency was assessed by histochemical staining forβ-glucuronidase(GUS).Finally,the transgenic nature of regenerated plants was verified by polymerase chain reaction(PCR)-based genotyping for the presence of the GUS and bialaphos resistance(bar)genes,histochemical staining for GUS protein,and the QuickStix strip assay for bar protein.The transformation efficiency of T.monococcum genotype PI428182 was 94.4%;the efficiencies of four hexaploid triticale genotypes Lin456,ZS3297,ZS1257,and ZS3224 were 52.1,41.2,19.4,and 16.0%,respectively;and the transformation efficiency of rye cultivar Lanzhou Heimai was 7.8%.Fluorescence in situ hybridization(FISH)and genomic in situ hybridization(GISH)analyses indicated that the GUS transgenes were integrated into the distal or near centromere(proximal)regions of the chromosomes in transgenic T.monococcum and hexaploid triticale plants.In the transgenic hexaploid triticale plants,the foreign DNA fragment was randomly integrated into the AABB and RR genomes.Furthermore,the transgene was almost stably inherited in the next generation by Mendel’s law.The findings in this study will promote the genetic improvement of the three plant species for grain or forage production and the improvement of cereal species including wheat for functional genomics studies.
文摘The research in silicon photonics has been booming due to its potential for lowcost,reliable,energy-efficient and high-density chip-wise integration using widely available CMOS technology,featuring the tremendous success in modulator,detector and other passive waveguide components in industry.However,the absence of efficient and reliable electrical to optical converter on Si platform has been considered as“the last piece of the puzzle”,hindered by the in-direct bandgap property of Si bulk materials.CompoundⅢ–Ⅴsemiconductor devices offer highly efficient optical light emitting sources and optical amplifiers,hence the compound semiconductor materials and devices on Si platform are drawing more and more attention nowadays as it could make possible the long-dreamed light sources on Si substrates by combining their advantages with silicon ICs,enabling the fabrication of full functional optoelectronic circuits,chip-to-chip and even system-to-system optical chips.
基金Youth Project of Natural Science Foundation of Hebei Province(C2019402141)Science and Technology Research Project for Colleges and Universities in Hebei Province(QN2019215)Science and Technology Research and Development Plan of Handan City(1727201061).
文摘[Objectives]To use liquid chromatography-mass spectrometry technology to analyze the chemical composition of traditional Chinese medicine and explore its application in the evaluation of quality stability of traditional Chinese medicine.[Methods]Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-QTOF-MS)was used to detect the samples of Moluodan concentrated pills.By comparing and analyzing the detection results of 10 different batches of Moluodan concentrated pills,combined with principal component analysis(PCA),the quality stability of Moluodan concentrated pills was evaluated.[Results]A total of 367 chemical components were identified in Moluodan concentrated pills.The average repetition rate of the chemical components contained in the 10 different batches of samples reached 92%.The overall quality stability of the Moluodan concentrated pills was good.[Conclusions]The UPLC-QTOF-MS technology combined with PCA provides a reference for the overall quality evaluation of Moluodan concentrated pills,and provides new detection methods and ideas for the analysis of the components of Chinese medicine.
基金supported by the National Key R&D Program of China(2021YFD1401000)the Zhongyuan Scholar Program(234000510002)the Natural Science Foundation of Henan province(242300421113).
文摘Broad-spectrum resistance(BSR)is highly sought after for the effective management of crop diseases.However,genes suitable for developing BSR remain scarce.In this study,we demonstrate the development of BSR to wheat yellow rust(YR),powdery mildew(PM),and leaf rust(LR)diseases elicited by three biotrophic fungal pathogens using a newly defined module,namely,RFEL1-NPR3.RFEL1 is an active RING-finger E3 ubiquitin ligase identified in diploid and polyploid wheat species,which ubiquitinates and promotes the degradation of wheat NPR3(TaNPR3),an important negative immune regulator conserved in higher plants,via the 26S proteasome system.Downregulation of TaNPR3 by either overexpressing RFEL1 or knocking out TaNPR3 confers strong resistance against four different YR races as well as the PM and LR diseases without adverse effects on wheat growth and yield traits.Notably,the enhanced disease resistance exhibited by RFEL1-overexpressing and TaNPR3-knockout lines is correlated with increased expression of defense related genes and elevated stability of NPR1,a pivotal positive regulator of plant immune signaling.Our findings underscore the importance of ubiquitination-dependent NPR3 degradation in plant immunity and advocate for the application of the RFEL1-NPR3 module in engineering BSR against biotrophic fungal pathogens in wheat and other crops.
基金This work was supported by the Research Grants Council of Hong Kong(14209519,C4050-21E)The Chinese University of Hong Kong(Group Research Scheme),National Natural Science Foundation of China(62174144)+4 种基金Shenzhen Fundamental Research Fund(JCYJ20210324115605016,JCYJ20210324120204011)Shenzhen Key Laboratory Project(ZDSYS201603311644527),Optical Communication Core Chip Research Platform,UK Engineering and Physical Sciences Research Council(EP/P006973/1,EP/T01394X/1,EP/T028475/1)National Epitaxy Facility,European project H2020-ICT-PICTURE(780930)Royal Academy of Engineering(RF201617/16/28)French National Research Agency under the Investissements d’avenir ANR-10-IRT-05 and ANR-15-IDEX-02 and French RENATECH network.The devices were partially fabricated in the Core Research Facilities at Southern University of Science and Technology,whose engineers provided technical support.
文摘Robust laser sources are a fundamental building block for contemporary information technologies.Originating from condensed-matter physics,the concept of topology has recently entered the realm of optics,offering fundamentally new design principles for lasers with enhanced robustness.In analogy to the well-known Majorana fermions in topological superconductors,Dirac-vortex states have recently been investigated in passive photonic systems and are now considered as a promising candidate for robust lasers.Here,we experimentally realize the topological Diracvortex microcavity lasers in InAs/InGaAs quantum-dot materials monolithically grown on a silicon substrate.We observe room-temperature continuous-wave linearly polarized vertical laser emission at a telecom wavelength.We confirm that the wavelength of the Dirac-vortex laser is topologically robust against variations in the cavity size,and its free spectral range defies the universal inverse scaling law with the cavity size.These lasers will play an important role in CMOS-compatible photonic and optoelectronic systems on a chip.
基金supported by the National Natural Science Foundation of China(62293521,62174167,12205119)Shanghai Rising-Star Program(22QA1410700)+2 种基金China Postdoctoral Science Foundation(2022M723282)Zhejiang Provincial Natural Science Foundation of China(LQ23F040002)Jiaxing Municipal Public Welfare Research Project(2022AY10027).
文摘A reliable,efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics.Despite the impressive advances that have been made in developing 1.3-μm Si-based quantum dot(QD)lasers,extending the wavelength window to the widely used 1.55-μm telecommunication region remains difficult.In this study,we develop a novel photonic integration method of epitaxial growth of III-V on a wafer-scale InP-on-Si(100)(InPOS)heterogeneous substrate fabricated by the ion-cutting technique to realize integrated lasers on Si substrate.This ion-cutting plus epitaxial growth approach decouples the correlated root causes of many detrimental dislocations during heteroepitaxial growth,namely lattice and domain mismatches.Using this approach,we achieved state-of-the-art performance of the electrically-pumped,continuouswave(CW)1.55-μm Si-based laser with a room-temperature threshold current density of 0.65 kA/cm^(-2),and output power exceeding 155mW per facet without facet coating in CW mode.CW lasing at 120℃ and pulsed lasing at over 130℃ were achieved.This generic approach is also applied to other material systems to provide better performance and more functionalities for photonics and microelectronics.
基金Engineering and Physical Sciences Research Council(EPSRC)(EP/P006973/1)Royal Academy of Engineering(RF201617/16/28)Chinese Scholarship Council
文摘We report low-noise, high-performance single transverse mode 1.3 μm InAs/GaAs quantum dot lasers monolithically grown on silicon(Si) using molecular beam epitaxy. The fabricated narrow-ridge-waveguide Fabry–Perot(FP) lasers have achieved a room-temperature continuous-wave(CW) threshold current of 12.5 mA and high CW temperature tolerance up to 90°C. An ultra-low relative intensity noise of less than-150 dB∕Hz is measured in the 4–16 GHz range. Using this low-noise Si-based laser, we then demonstrate 25.6 Gb/s data transmission over13.5 km SMF-28. These low-cost FP laser devices are promising candidates to provide cost-effective solutions for use in uncooled Si photonics transmitters in inter/hyper data centers and metropolitan data links.
基金This research was supported by the National Natural Science Foundation of China(No.62174144)Shenzhen Fundamental Research Fund(Nos.JCYJ20210324115605016 and JCYJ20210324120204011)+7 种基金Optical Communication Core Chip Research Platform,Shenzhen Key Laboratory Project(No.ZDSYS201603311644527)Longgang Key Laboratory Project(Nos.ZSYS2017003 and LGKCZSYS2018000015)Longgang Matching Support Fund(Nos.CXPTPT-2017-YJ-002 and 201617486)President's Fund(PF01000154)UK Engineering and Physical Sciences Research Council(EP/P006973/1 and National Epitaxy Facility)European project H2020-ICT-PICTURE(780930)Royal Academy of Engineering(RF201617/16/28)French government managed by ANR under the Investissements davenir ANR-10-IRT-05 and ANR-15-IDEX-02 and French RENATECH network.
文摘Monolithic integration of Ⅲ-Ⅴ lasers with small footprint, good coherence, and low power consumption based on a CMOS-compatible Si substrate have been known as an efficient route towards high-density optical interconnects in the photonic integrated circuits. However, the material dissimilarities between Si and Ⅲ-Ⅴ materials limit the performance of monolithic microlasers. Here, under the pumping condition of a continuous-wave 632.8 nm He–Ne gas laser at room temperature, we achieved an InAs/GaAs quantum dot photonic crystal bandedge laser, which is directly grown on an on-axis Si(001) substrate, which provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform.
基金Beijing University of Posts and Telecommunications(BUPT)(IPOC2016ZT01)National Natural Science Foundation of China(NSFC)(61474008,61574019,61674020)+1 种基金International Science&Technology Cooperation Program of China(2011DFR11010)111 Project of China(B07005)
文摘We report on the first electrically pumped continuous-wave(CW) In As/Ga As quantum dot(QD) laser grown on Si with a GaInP upper cladding layer. A QD laser structure with a Ga_(0.51)In_(0.49)P upper cladding layer and an Al_(0.53)Ga_(0.47)As lower cladding layer was directly grown on Si by metal–organic chemical vapor deposition. It demonstrates the postgrowth annealing effect on the QDs was relieved enough with the GaInP upper cladding layer grown at a low temperature of 550°C. Broad-stripe edge-emitting lasers with 2-mm cavity length and 15-μm stripe width were fabricated and characterized. Under CW operation, room-temperature lasing at ~1.3 μm has been achieved with a threshold density of 737 A∕cm^2 and a single-facet output power of 21.8 mW.
基金supported by the National Natural Science Foundation of China (61974014)the EPSRC Future Compound Semiconductor Manufacturing Hub (EP/P006973/1)。
文摘Multifunctional devices are of great interest for integration and miniaturization on the same platform, but simple addition of functionalities would lead to excessively large devices. Here, the photodetection and chemical sensing device is developed based on two-dimensional(2D) glassygraphene that meets similar property requirements for the two functionalities. An appropriate bandgap arising from the distorted lattice structure enables glassy graphene to exhibit comparable or even improved photodetection and chemical sensing capability, compared with pristine graphene. Due to strong interactions between glassy graphene and the ambient atmosphere, the devices are less sensitive to photoinduced desorption than the ones based on graphene. Consequently,the few-layer glassy graphene device delivers positive photoresponse, with a responsivity of 0.22 A W^(-1) and specific detectivity reaching ~10^(10) Jones under 405 nm illumination.Moreover, the intrinsic defects and strain in glassy graphene can enhance the adsorption of analytes, leading to high chemical sensing performance. Specifically, the extracted signalto-noise-ratio of the glassy graphene device for detecting acetone is 48, representing more than 50% improvement over the device based on graphene. Additionally, bias-voltage-and thickness-dependent volatile organic compound(VOC) sensing features are identified, indicating the few-layer glassy graphene is more sensitive. This study successfully demonstrates the potential of glassy graphene for integrated photodetection and chemical sensing, providing a promising solution for multifunctional applications further beyond.
基金the financial support from the Paul Instrument Fund of the Royal Society(PI150018)the development of the i-TCSPC as well as the support of EPSRC Grants EP/P000916/1,EP/P000886/1,EP/P006973/1the EPSRC National Epitaxy Facility.
文摘Continuous room temperature nanowire lasing from silicon-integrated optoelectronic elements requires careful optimisation of both the lasing cavity Q-factor and population inversion conditions.We apply time-gated optical interferometry to the lasing emission from high-quality GaAsP/GaAs quantum well nanowire laser structures,revealing high Q-factors of 1250±90 corresponding to end-facet reflectivities of R=0.73±0.02.By using optimised direct-indirect band alignment in the active region,we demonstrate a well-refilling mechanism providing a quasifour-level system leading to multi-nanosecond lasing and record low room temperature lasing thresholds(~6μJ cm^(−2) pulse−1)for Ⅲ-Ⅴ nanowire lasers.Our findings demonstrate a highly promising new route towards continuously operating silicon-integrated nanolaser elements.
基金Royal Academy of Engineering(RF201617/16/28)Engineering and Physical Sciences Research Council(EP/R041792/1,EP/T01394X/1)。
文摘Semiconductor mode-locked lasers(MLLs)are promising frequency comb sources for dense wavelength-divisionmultiplexing(DWDM)data communications.Practical data communication requires a frequency-stable comb source in a temperature-varying environment and a minimum tone spacing of 25 GHz to support high-speed DWDM transmissions.To the best of our knowledge,however,to date,there have been no demonstrations of comb sources that simultaneously offer a high repetition rate and stable mode spacing over an ultrawide temperature range.Here,we report a frequency comb source based on a quantum dot(QD)MLL that generates a frequency comb with stable mode spacing over an ultrabroad temperature range of 20–120℃.The two-section passively mode-locked In As QD MLL comb source produces an ultra-stable fundamental repetition rate of 25.5 GHz(corresponding to a 25.5 GHz spacing between adjacent tones in the frequency domain)with a variation of 0.07 GHz in the tone spacing over the tested temperature range.By keeping the saturable absorber reversely biased at-2 V,stable mode-locking over the whole temperature range can be achieved by tuning the current of the gain section only,providing easy control of the device.At an elevated temperature of 100℃,the device shows a 6 d B comb bandwidth of 4.81 nm and 31 tones with>36 d B optical signal-to-noise ratio.The corresponding relative intensity noise,averaged between 0.5 GHz and 10 GHz,is-146 d Bc∕Hz.Our results show the viability of the In As QD MLLs as ultra-stable,uncooled frequency comb sources for low-cost,large-bandwidth,and low-energy-consumption optical data communications.
基金National Key Research and Development Program of China,Grant/Award Number:2021YFB2800500National Natural Science Foundation of China,Grant/Award Numbers:62375243,61574138,61974131,62035013,62105281+2 种基金Natural Science Foundation of ZhejiangProvince, Grant/Award Numbers:LD22E010001, LR23E030002,LGJ21F050001Major Scientific Project ofZhejiang LabEngineering and PhysicalSciences Research Council (EPSRC),Grant/Award Numbers: EP/P006973/1,EP/R029075/1, EP/T028475/1, EP/V036327/1, EP/V048732/1, EP/X015300/1。
文摘The rapid development of emerging technologies observed in recent years,such as artificial intelligence, machine learning, mobile internet, big data,cloud computing, and the Internet of Everything, are generating escalatingdemands for expanding the capacity density, and speed in next-generation opticalcommunications. This poses a significant challenge to existing communicationtechniques. Within this context, the integration of near-infraredbroadband, tunable, and high-gain luminescent materials into silicon opticalcircuits or fiber architectures to transmit and modulate light shows enormouspotential for advancing next-generation communication techniques. Here, thisreview provides an overview of the recent breakthroughs in near-infrared luminescentepitaxial/colloidal quantum dots, and metal-active-center-doped materialsfor broadband optical amplifiers and tunable lasers. We also expound onefforts to enhance the bandwidth and gain of these materials-based amplifiersand lasers, exploring the challenges associate with developing ultra-broadbandand high-speed optical communication systems. Additionally, the potentialapplications in Fifth Generation Fixed Networks, integration with 5G and 6Gwireless networks, compensation for current Si electronic based CMOS forhigh computing capability, and the prospects of these light sources for nextgenerationoptoelectronic devices are discussed.
