Direct growth and patterning of atomically thin two-dimensional(2D)materials on various substrates are essential steps towards enabling their potential for use in the next generation of electronic and optoelectronic d...Direct growth and patterning of atomically thin two-dimensional(2D)materials on various substrates are essential steps towards enabling their potential for use in the next generation of electronic and optoelectronic devices.The conventional gas-phase growth techniques,however,are not compatible with direct patterning processes.Similarly,the condensed-phase methods,based on metal oxide deposition and chalcogenization processes,require lengthy processing times and high temperatures.Here,a novel self-limiting laser crystallization process for direct crystallization and patterning of 2D materials is demonstrated.It takes advantage of significant differences between the optical properties of the amorphous and crystalline phases.Pulsed laser deposition is used to deposit a thin layer of stoichiometric amorphous molybdenum disulfide(MoS2)film(∼3 nm)onto the fused silica substrates.A tunable nanosecond infrared(IR)laser(1064 nm)is then employed to couple a precise amount of power and number of pulses into the amorphous materials for controlled crystallization and direct writing processes.The IR laser interaction with the amorphous layer results in fast heating,crystallization,and/or evaporation of the materials within a narrow processing window.However,reduction of the midgap and defect states in the as crystallized layers decreases the laser coupling efficiency leading to higher tolerance to process parameters.The deliberate design of such laser 2D material interactions allows the selflimiting crystallization phenomena to occur with increased quality and a much broader processing window.This unique laser processing approach allows high-quality crystallization,direct writing,patterning,and the integration of various 2D materials into future functional devices.展开更多
Recently, there has been substantial interest in the large-scale synthesis of hierarchically architectured transition metal dichalcogenides and designing electrodes for energy conversion and storage applications such ...Recently, there has been substantial interest in the large-scale synthesis of hierarchically architectured transition metal dichalcogenides and designing electrodes for energy conversion and storage applications such as electrocatalysis, rechargeable batteries, and supercapacitors. Here we report a novel hybrid laser-assisted micro/nanopatterning and sulfurization method for rapid manufacturing of hierarchically architectured molybdenum disulfide (MoS2) layers directly on molybdenum sheets. This laser surface structuring not only provides the ability to design specific micro/nanostructured patterns but also significantly enhances the crystal growth kinetics. Micro and nanoscale characterization methods are employed to study the morphological, structural, and atomistic characteristics of the formed crystals at various laser processing and crystal growth conditions. To compare the performance characteristics of the laser-structured and unstructured samples, Li-ion battery cells are fabricated and their energy storage capacity is measured. The hierarchically architectured MoS2 crystals show higher performance with specific capacities of about 10 mAh cm-2, at a current rate of 0.1 mA cm-2. This rapid laser patterning and growth of 2D materials directly on conductive sheets may enable the future large-scale and roll-to-roll manufacturing of energy and sensing devices.展开更多
Modern three-dimensional nanofabrication requires both additive and subtractive processes.However,both processes are largely isolated and generally regarded as incompatible with each other.In this study,we developed s...Modern three-dimensional nanofabrication requires both additive and subtractive processes.However,both processes are largely isolated and generally regarded as incompatible with each other.In this study,we developed simultaneous additive and subtractive fabrication processes using two-photon polymerization followed by femtosecond(fs)laser multiphoton ablation.To demonstrate the new capability,submicrometer polymer fibers containing periodic holes of 500-nm diameter and microfluidic channels of 1-mm diameter were successfully fabricated.This method combining both two-photon polymerization and fs laser ablation improves the nanofabrication efficiency and enables the fabrication of complex three-dimensional micro-/nanostructures,promising for a wide range of applications in integrated optics,microfluidics and microelectromechanical systems.展开更多
Advanced micro/nanofabrication of functional materials and structures with various dimensions represents a key research topic in modem nanoscience and technology and becomes critically important for numerous emerging ...Advanced micro/nanofabrication of functional materials and structures with various dimensions represents a key research topic in modem nanoscience and technology and becomes critically important for numerous emerging technologies such as nanoelectronics, nanopho- tonics and micro/nanoelectromechanical systems. This review systematically explores the non-conventional material processing approaches in fabricating nanomaterials and micro/nanostructures of various dimensions which are challenging to be fabricated via conventional approaches. Research efforts are focused on laser-based techniques for the growth and fabrication of one-dimensional （1D）, two-dimensional （2D） and three-dimensional （3D） nanomaterials and micro/nanostructures. The following research topics are covered, including： 1） laser-assisted chemical vapor deposition （CVD） for highly efficient growth and integration of 1D nanomaterial of carbon nanotubes （CNTs）, 2） laser direct writing （LDW） of graphene ribbons under ambient conditions, and 3） LDW of 3D micro/nanostructures via additive and subtractive processes. Comparing with the conventional fabrication methods, the laser-based methods exhibit several unique advantages in the micro/nanofabrication of advanced functional materials and structures. For the 1D CNT growth, the laser-assisted CVD process can realize both rapid material synthesis and tight control of growth location and orientation of CNTs due to the highly intense energy delivery and laser-induced optical near-field effects. For the 2D graphene synthesis and patterning, roomtemperature and open-air fabrication of large-scale graphene patterns on dielectric surface has been successfully realized by a LDW process. For the 3D micro/nanofabrica- tion, the combination of additive two-photon polymeriza- tion （TPP） and subtractive multi-photon ablation （MPA） processes enables the fabrication of arbitrary complex 3D micro/nanostructures which tional fabrication methods are challenging for conven- Considering the numerous unique advantages of laser-based techniques, the laser- based micro/nanofabrication is expected to play a more and more important role in the fabrication of advanced functional micro/nano-devices.展开更多
基金This work is supported by the Intermural Grant Program(IGP)at Auburn University.
文摘Direct growth and patterning of atomically thin two-dimensional(2D)materials on various substrates are essential steps towards enabling their potential for use in the next generation of electronic and optoelectronic devices.The conventional gas-phase growth techniques,however,are not compatible with direct patterning processes.Similarly,the condensed-phase methods,based on metal oxide deposition and chalcogenization processes,require lengthy processing times and high temperatures.Here,a novel self-limiting laser crystallization process for direct crystallization and patterning of 2D materials is demonstrated.It takes advantage of significant differences between the optical properties of the amorphous and crystalline phases.Pulsed laser deposition is used to deposit a thin layer of stoichiometric amorphous molybdenum disulfide(MoS2)film(∼3 nm)onto the fused silica substrates.A tunable nanosecond infrared(IR)laser(1064 nm)is then employed to couple a precise amount of power and number of pulses into the amorphous materials for controlled crystallization and direct writing processes.The IR laser interaction with the amorphous layer results in fast heating,crystallization,and/or evaporation of the materials within a narrow processing window.However,reduction of the midgap and defect states in the as crystallized layers decreases the laser coupling efficiency leading to higher tolerance to process parameters.The deliberate design of such laser 2D material interactions allows the selflimiting crystallization phenomena to occur with increased quality and a much broader processing window.This unique laser processing approach allows high-quality crystallization,direct writing,patterning,and the integration of various 2D materials into future functional devices.
基金partially funded by the U.S.National Science Foundation(NSF)under Grant No.1923363.
文摘Recently, there has been substantial interest in the large-scale synthesis of hierarchically architectured transition metal dichalcogenides and designing electrodes for energy conversion and storage applications such as electrocatalysis, rechargeable batteries, and supercapacitors. Here we report a novel hybrid laser-assisted micro/nanopatterning and sulfurization method for rapid manufacturing of hierarchically architectured molybdenum disulfide (MoS2) layers directly on molybdenum sheets. This laser surface structuring not only provides the ability to design specific micro/nanostructured patterns but also significantly enhances the crystal growth kinetics. Micro and nanoscale characterization methods are employed to study the morphological, structural, and atomistic characteristics of the formed crystals at various laser processing and crystal growth conditions. To compare the performance characteristics of the laser-structured and unstructured samples, Li-ion battery cells are fabricated and their energy storage capacity is measured. The hierarchically architectured MoS2 crystals show higher performance with specific capacities of about 10 mAh cm-2, at a current rate of 0.1 mA cm-2. This rapid laser patterning and growth of 2D materials directly on conductive sheets may enable the future large-scale and roll-to-roll manufacturing of energy and sensing devices.
基金This research work was financially supported by National Science Foundation(CMMI 0900419 and 0758199)National Natural Science Foundation of China(grant no.90923039)。
文摘Modern three-dimensional nanofabrication requires both additive and subtractive processes.However,both processes are largely isolated and generally regarded as incompatible with each other.In this study,we developed simultaneous additive and subtractive fabrication processes using two-photon polymerization followed by femtosecond(fs)laser multiphoton ablation.To demonstrate the new capability,submicrometer polymer fibers containing periodic holes of 500-nm diameter and microfluidic channels of 1-mm diameter were successfully fabricated.This method combining both two-photon polymerization and fs laser ablation improves the nanofabrication efficiency and enables the fabrication of complex three-dimensional micro-/nanostructures,promising for a wide range of applications in integrated optics,microfluidics and microelectromechanical systems.
文摘Advanced micro/nanofabrication of functional materials and structures with various dimensions represents a key research topic in modem nanoscience and technology and becomes critically important for numerous emerging technologies such as nanoelectronics, nanopho- tonics and micro/nanoelectromechanical systems. This review systematically explores the non-conventional material processing approaches in fabricating nanomaterials and micro/nanostructures of various dimensions which are challenging to be fabricated via conventional approaches. Research efforts are focused on laser-based techniques for the growth and fabrication of one-dimensional （1D）, two-dimensional （2D） and three-dimensional （3D） nanomaterials and micro/nanostructures. The following research topics are covered, including： 1） laser-assisted chemical vapor deposition （CVD） for highly efficient growth and integration of 1D nanomaterial of carbon nanotubes （CNTs）, 2） laser direct writing （LDW） of graphene ribbons under ambient conditions, and 3） LDW of 3D micro/nanostructures via additive and subtractive processes. Comparing with the conventional fabrication methods, the laser-based methods exhibit several unique advantages in the micro/nanofabrication of advanced functional materials and structures. For the 1D CNT growth, the laser-assisted CVD process can realize both rapid material synthesis and tight control of growth location and orientation of CNTs due to the highly intense energy delivery and laser-induced optical near-field effects. For the 2D graphene synthesis and patterning, roomtemperature and open-air fabrication of large-scale graphene patterns on dielectric surface has been successfully realized by a LDW process. For the 3D micro/nanofabrica- tion, the combination of additive two-photon polymeriza- tion （TPP） and subtractive multi-photon ablation （MPA） processes enables the fabrication of arbitrary complex 3D micro/nanostructures which tional fabrication methods are challenging for conven- Considering the numerous unique advantages of laser-based techniques, the laser- based micro/nanofabrication is expected to play a more and more important role in the fabrication of advanced functional micro/nano-devices.
