Supercritical lens(SCL)can break the diffraction limit in the far field and has been demonstrated for high-resolution scanning confocal imaging.Its capability in sharper focusing and needle-like long focal depth shoul...Supercritical lens(SCL)can break the diffraction limit in the far field and has been demonstrated for high-resolution scanning confocal imaging.Its capability in sharper focusing and needle-like long focal depth should allow high-resolution lithography at violet or ultraviolet(UV)wavelength,however,this has never been experimentally demonstrated.As a proof of concept,in this paper SCLs operating at 405 nm(h-line)wavelength with smaller full-width-at-half-maximum focal spot and longer depth of focus than conventional Fresnel zone lens while maintaining controlled side lobes are designed for direct laser writing(DLW)lithography.Aluminum nitride(AlN)with a high refractive index and low loss in UVvisible range is used to fabricate nanopillar-based metasurfaces structure for the metalens.Grating arrays with improved pitch resolution are fabricated using the SCLs with sub-diffraction-limit focusing capability.The AlN-based metasurface for SCLs at short wavelength for DLW could extend further to UV or deep UV lithography and might be of great interest to both the research and industry applications.展开更多
Transition metal dichalcogenides(TMDs)and perovskites are among the most attractive and widely investigated semiconductors in the recent decade.They are promising materials for various applications,such as photodetect...Transition metal dichalcogenides(TMDs)and perovskites are among the most attractive and widely investigated semiconductors in the recent decade.They are promising materials for various applications,such as photodetection,solar energy harvesting,light emission,and many others.Combining these materials to form heterostructures can enrich the already fascinating properties and bring up new phenomena and opportunities.Work in this field is growing rapidly in both fundamental studies and device applications.Here,we review the recent findings in the perovskite-TMD heterostructures and give our perspectives on the future development of this promising field.The fundamental properties of the perovskites,TMDs,and their heterostructures are discussed first,followed by a summary of the synthesis methods of the perovskites and TMDs and the approaches to obtain high-quality interfaces.Particular attention is paid to the TMD-perovskite heterostructures that have been applied in solar cells and photodetectors with notable performance improvement.Finally through our analysis,we propose an outline on further fundamental studies and the promising applications of perovskite-TMD heterostructures.展开更多
ZnO thin films were grown on Si （111） substrates by low-pressure metal-organic chemical vapor deposition. The crystal structures and electrical properties of as-grown sample were investigated by scanning electron mi...ZnO thin films were grown on Si （111） substrates by low-pressure metal-organic chemical vapor deposition. The crystal structures and electrical properties of as-grown sample were investigated by scanning electron microscopy （SEM） and conductive atomic force microscopy （C-AFM）. It can be seen that with increasing growth temperature, the surface morphology of ZnO thin films changed from flake-like to cobblestones-like structure. The current maps were simultaneously recorded with the topography, which was gained by C-AFM contact mode. Conductivity for the off-axis facet planes presented on ZnO grains enhanced. Measurement results indicate that the off-axis facet planes were more electrically active than the c-plane of ZnO flakes or particles probably due to lower Schottky barrier height of the off-axis facet planes.展开更多
Graphene is being actively explored as a candidate material for flexible and stretchable devices. However, the development of graphene-based flexible photonic devices, i.e. photodetectors, is hindered by the low absor...Graphene is being actively explored as a candidate material for flexible and stretchable devices. However, the development of graphene-based flexible photonic devices, i.e. photodetectors, is hindered by the low absorbance of the single layer of carbon atoms. Recently, van der Waals bonded carbon nanotube and graphene hybrid films have demonstrated excellent photoresponsivity, and the use of vein-like carbon nanotube networks resulted in significantly higher mechanical strength. Here, we report for the first time, a flexible photodetector with a high photoresponsivity of - 51 A/W and a fast response time of - 40 ms over the visible range, revealing the unique potential of this emerging all-carbon hybrid films for flexible devices. In addition, the device exhibits good robustness against repetitive bending, suggesting its applicability in large-area matrix-array flexible photodetectors.展开更多
Exposure to a growth factor abundant milieu has remarkable regenerative and rejuvenating effects on organ diseases,tissue damage,and regeneration,including skeletal system defects and bone regeneration.Although the in...Exposure to a growth factor abundant milieu has remarkable regenerative and rejuvenating effects on organ diseases,tissue damage,and regeneration,including skeletal system defects and bone regeneration.Although the introduction of candidate growth factors into relevant fields has been reported,their regenerative effects remain unsatisfactory,mainly because of the experimental challenges with limited types of growth factors,elusive dosage adjustment,and asynchronous stem cell activation with cytokine secretion.Here,an innovative hydrogel recapitulating a growth factor-enriched microenvironment(GEM)for regenerative advantage,is reported.This sulfated hydrogel includes bone morphogenetic protein-2(BMP-2),an essential growth factor in osteogenesis,to direct mesenchymal stem cell(MSC)differentiation,stimulate cell proliferation,and improve bone formation.The semi-synthetic hydrogel,sulfonated gelatin(S-Gelatin),can amplify BMP-2 signaling in mouse MSCs by enhancing the binding between BMP-2 and BMP-2 type II receptors(BMPR2),which are located on MSC nuclei and activated by the hydrogel.Importantly,the dramatically improved cytokine secretion of MSCs throughout regeneration confirms the growth factor-acquiring potential of S-Gelatin/rhBMP-2 hydrogel,leading to the vascularization enhancement.These findings provide a new strategy to achieve an in situ GEM and accelerated bone regeneration by amplifying the regenerative capacity of rhBMP-2 and capturing endogenous growth factors.展开更多
基金financially supported by A*STAR under IRG program(Grant No.A2083c0058)and the MTC Programmatic(Grant No.M22L1b0110)Z Wang thanks the GAP Funding(I21D1AG010)+4 种基金the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-049)the National Natural Science Foundation of China(Grant Nos.12134013 and 62322512)the National Key Research and Development Program of China(Grant No.2022YFB3607300)the CAS Pioneer Hundred Talents Program,and support from the University of Science and Technology of China’s Centre for MicroNanoscale Research and Fabrication.
文摘Supercritical lens(SCL)can break the diffraction limit in the far field and has been demonstrated for high-resolution scanning confocal imaging.Its capability in sharper focusing and needle-like long focal depth should allow high-resolution lithography at violet or ultraviolet(UV)wavelength,however,this has never been experimentally demonstrated.As a proof of concept,in this paper SCLs operating at 405 nm(h-line)wavelength with smaller full-width-at-half-maximum focal spot and longer depth of focus than conventional Fresnel zone lens while maintaining controlled side lobes are designed for direct laser writing(DLW)lithography.Aluminum nitride(AlN)with a high refractive index and low loss in UVvisible range is used to fabricate nanopillar-based metasurfaces structure for the metalens.Grating arrays with improved pitch resolution are fabricated using the SCLs with sub-diffraction-limit focusing capability.The AlN-based metasurface for SCLs at short wavelength for DLW could extend further to UV or deep UV lithography and might be of great interest to both the research and industry applications.
基金J.H.Teng acknowledges A*STAR for funding support in Grants A20E5c0084,A2083c0058 and CRF SC25/21-110318.
文摘Transition metal dichalcogenides(TMDs)and perovskites are among the most attractive and widely investigated semiconductors in the recent decade.They are promising materials for various applications,such as photodetection,solar energy harvesting,light emission,and many others.Combining these materials to form heterostructures can enrich the already fascinating properties and bring up new phenomena and opportunities.Work in this field is growing rapidly in both fundamental studies and device applications.Here,we review the recent findings in the perovskite-TMD heterostructures and give our perspectives on the future development of this promising field.The fundamental properties of the perovskites,TMDs,and their heterostructures are discussed first,followed by a summary of the synthesis methods of the perovskites and TMDs and the approaches to obtain high-quality interfaces.Particular attention is paid to the TMD-perovskite heterostructures that have been applied in solar cells and photodetectors with notable performance improvement.Finally through our analysis,we propose an outline on further fundamental studies and the promising applications of perovskite-TMD heterostructures.
基金financially supported by the National Natural Science Foundation of China (Nos. 11175038 and 51102036)the Fundamental Research Funds for the Central Universities (No. DC110314)
文摘ZnO thin films were grown on Si （111） substrates by low-pressure metal-organic chemical vapor deposition. The crystal structures and electrical properties of as-grown sample were investigated by scanning electron microscopy （SEM） and conductive atomic force microscopy （C-AFM）. It can be seen that with increasing growth temperature, the surface morphology of ZnO thin films changed from flake-like to cobblestones-like structure. The current maps were simultaneously recorded with the topography, which was gained by C-AFM contact mode. Conductivity for the off-axis facet planes presented on ZnO grains enhanced. Measurement results indicate that the off-axis facet planes were more electrically active than the c-plane of ZnO flakes or particles probably due to lower Schottky barrier height of the off-axis facet planes.
文摘Graphene is being actively explored as a candidate material for flexible and stretchable devices. However, the development of graphene-based flexible photonic devices, i.e. photodetectors, is hindered by the low absorbance of the single layer of carbon atoms. Recently, van der Waals bonded carbon nanotube and graphene hybrid films have demonstrated excellent photoresponsivity, and the use of vein-like carbon nanotube networks resulted in significantly higher mechanical strength. Here, we report for the first time, a flexible photodetector with a high photoresponsivity of - 51 A/W and a fast response time of - 40 ms over the visible range, revealing the unique potential of this emerging all-carbon hybrid films for flexible devices. In addition, the device exhibits good robustness against repetitive bending, suggesting its applicability in large-area matrix-array flexible photodetectors.
基金supported by the National Natural Science Foundation of China for Innovative Research Groups(Grant No.51621002)the Fundamental Research Funds for the Central Universities,State Administration of Foreign Experts Affairs P.R.China(Grant No.B14018)+1 种基金National Natural Science Foundation of China(No.31870953)National Key R&D Program of China(2018YFE0201500).
文摘Exposure to a growth factor abundant milieu has remarkable regenerative and rejuvenating effects on organ diseases,tissue damage,and regeneration,including skeletal system defects and bone regeneration.Although the introduction of candidate growth factors into relevant fields has been reported,their regenerative effects remain unsatisfactory,mainly because of the experimental challenges with limited types of growth factors,elusive dosage adjustment,and asynchronous stem cell activation with cytokine secretion.Here,an innovative hydrogel recapitulating a growth factor-enriched microenvironment(GEM)for regenerative advantage,is reported.This sulfated hydrogel includes bone morphogenetic protein-2(BMP-2),an essential growth factor in osteogenesis,to direct mesenchymal stem cell(MSC)differentiation,stimulate cell proliferation,and improve bone formation.The semi-synthetic hydrogel,sulfonated gelatin(S-Gelatin),can amplify BMP-2 signaling in mouse MSCs by enhancing the binding between BMP-2 and BMP-2 type II receptors(BMPR2),which are located on MSC nuclei and activated by the hydrogel.Importantly,the dramatically improved cytokine secretion of MSCs throughout regeneration confirms the growth factor-acquiring potential of S-Gelatin/rhBMP-2 hydrogel,leading to the vascularization enhancement.These findings provide a new strategy to achieve an in situ GEM and accelerated bone regeneration by amplifying the regenerative capacity of rhBMP-2 and capturing endogenous growth factors.
