Native dejects in HfSiO4 are investigated by first principles calculations. Transition levels of native detects can be accurately described by employing the nonlocal HSE06 hybrid functional. This methodology overcomes...Native dejects in HfSiO4 are investigated by first principles calculations. Transition levels of native detects can be accurately described by employing the nonlocal HSE06 hybrid functional. This methodology overcomes the band gap problem in traditional functionals. By band alignments among the Si, GaAs and HfSiO4. we are able to determine the position of defect levels in Si and GaAs relative to the HfSiO4 band gap. We evaluate the. possibility of these defects acting as fixed charge. Native defects lead to the change of valence and conduction band offsets. Gate leakage current is evaluated by the band offset. In addition, we also investigate diffusions of native defects, and discuss how they affect the MOS device performance.展开更多
Despite the long history of research that has focused on the role of defects on device performance, the studies have not always been fruitful. A major reason is because these defect studies have typically been conduct...Despite the long history of research that has focused on the role of defects on device performance, the studies have not always been fruitful. A major reason is because these defect studies have typically been conducted in a parallel mode wherein the semiconductor wafer was divided into multiple pieces for separate optical and structural characterization, as well as device fabrication and evaluation. The major limitation of this approach was that either the defect being investigated by structural characterization techniques was not the same defect that was affecting the device performance or else the defect was not characterized under normal device operating conditions. In this review, we describe a more comprehensive approach to defect study, namely a series mode, using an array of spatially-resolved optical, electrical, and structural characterization techniques, all at the individual defect level but applied sequentially on a fabricated device. This novel sequential approach enables definitive answers to key questions, such as:(ⅰ) how do individual defects affect device performance?(ⅱ) how does the impact depend on the device operation conditions?(ⅲ) how does the impact vary from one defect to another? Implementation of this different approach is illustrated by the study of individual threading dislocation defects in GaAs solar cells. Additionally,we briefly describe a 3-D Raman thermometry method that can also be used for investigating the roles of defects in high power devices and device failure mechanisms.展开更多
Two-dimensional(2D)semiconductors are emerging as promising candidates for the next-generation nanoelectronics.As a type of unique channel materials,2D semiconducting transition metal dichalcogenides(TMDCs),such as Mo...Two-dimensional(2D)semiconductors are emerging as promising candidates for the next-generation nanoelectronics.As a type of unique channel materials,2D semiconducting transition metal dichalcogenides(TMDCs),such as MoS2 and WS2,exhibit great potential for the state-of-the-art fieldeffect transistors owing to their atomically thin thicknesses,dangling-band free surfaces,and abundant band structures.Even so,the device performances of 2D semiconducting TMDCs are still failing to reach the theoretical values so far,which is attributed to the intrinsic defects,excessive doping,and daunting contacts between electrodes and channels.In this article,we review the up-to-date three strategies for improving the device performances of 2D semiconducting TMDCs:(i)the controllable synthesis of wafer-scale 2D semiconducting TMDCs single crystals to reduce the evolution of grain boundaries,(ii)the ingenious doping of 2D semiconducting TMDCs to modulate the band structures and suppress the impurity scatterings,and(iii)the optimization design of interfacial contacts between electrodes and channels to reduce the Schottky barrier heights and contact resistances.In the end,the challenges regarding the improvement of device performances of 2D semiconducting TMDCs are highlighted,and the further research directions are also proposed.We believe that this review is comprehensive and insightful for downscaling the electronic devices and extending the Moore’s law.展开更多
Two-dimensional(2D)semiconductors are attractive channels to shrink the scale of field-effect transistors(FETs),and among which the anisotropic one is more advantageous for a higher on-state current(I_(on)).Monolayer(...Two-dimensional(2D)semiconductors are attractive channels to shrink the scale of field-effect transistors(FETs),and among which the anisotropic one is more advantageous for a higher on-state current(I_(on)).Monolayer(ML)SnSe_(2),as an abundant,economic,nontoxic,and stable two-dimensional material,possesses an anisotropic electronic nature.Herein,we study the device performances of the ML SnSe_(2) metal-oxide-semiconductor FETs(MOSFETs)and deduce their performance limit to an ultrashort gate length(L_(g))and ultralow supply voltage(V_(dd))by using the ab initio quantum transport simulation.An ultrahigh I_(on) of 5,660 and 3,145µA/µm is acquired for the n-type 10-nm-L_(g) ML SnSe_(2) MOSFET at V_(dd)=0.7 V for high-performance(HP)and low-power(LP)applications,respectively.Specifically,until L_(g) scales down to 2 and 3 nm,the MOSFETs(at V_(dd)=0.65 V)surpass I_(on),intrinsic delay time(τ),and power-delay product(PDP)of the International Roadmap for Device and Systems(IRDS,2020 version)for HP and LP devices for the year 2028.Moreover,the 5-nm-L_(g) ML SnSe_(2) MOSFET(at V_(dd)=0.4 V)fulfills the IRDS HP device and the 7-nm-L_(g) MOSFET(at V_(dd)=0.55 V)fulfills the IRDS LP device for the year 2034.展开更多
In this paper,the pentacene-based organic field-effect transistors(OFETs)with poly(methyl methacrylate)(PMMA)as gate dielectrics were fabricated,and the effects of gate dielectric thickness and semiconductor thickness...In this paper,the pentacene-based organic field-effect transistors(OFETs)with poly(methyl methacrylate)(PMMA)as gate dielectrics were fabricated,and the effects of gate dielectric thickness and semiconductor thickness on the device performance were investigated.The optimal PMMA thickness is in the range of 350–400 nm to sustain a considerable current density and stable performance.The device performance depends on the thicknesses of the active layer non-monotonically,which can be explained by the morphology of the pentacene film and the position of the conducting channel in the active layer.The device with a pentacene thickness of 50 nm shows the best performance,which has a maximum hole mobility of 1.12 cm2/V·s.In addition,the introduction of a thin layer of tris-(8-hydroxyquinolinato)aluminum(Alq3)to the OFETs as a light-emitting material greatly decreases the device performance.展开更多
We propose four different models of three-terminal quantum dot thermoelectric devices. From general thermodynamic laws, we examine the rew;rsible efficiencies of the four different models. Based on the master equation...We propose four different models of three-terminal quantum dot thermoelectric devices. From general thermodynamic laws, we examine the rew;rsible efficiencies of the four different models. Based on the master equation, the expressions for the efficiency and power output are derived and the corresponding working regions are determined. Moreover, we particularly analyze the performance of a three-terminal hybrid quantum dot refrigerator. The performance characteristic curves and the optimal performance parameters are obtained. Finally, we discuss the influence of the nonradiative effects on the optimal performance parameters in detail.展开更多
We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the roto...We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the rotor part. When the rotor part is parallel with the stator part, a better rectifying performance can be found in the current-voltage curve. However, when the rotor part revolves to vertical with the stator part, the currents in the positive bias region decrease slightly. More importantly, the rectifying performance disappears. Thus this offers us a new method to modulate the rectifying behavior in molecular devices.展开更多
We investigate the effect of the formation process under pulse and dc modes on the performance of one transistor and one resistor （1 T1R） resistance random access memory （RRAM） device. All the devices are operated...We investigate the effect of the formation process under pulse and dc modes on the performance of one transistor and one resistor （1 T1R） resistance random access memory （RRAM） device. All the devices are operated under the same test conditions, except for the initial formation process with different modes. Based on the statistical results, the high resistance state （FIRS） under the dc forming mode shows a lower value with better distribution compared with that under the pulse mode. One of the possible reasons for such a phenomenon originates from different properties of conductive filament （CF） formed in the resistive switching layer under two different modes. For the dc forming mode, the formed filament is thought to be continuous, which is hard to be ruptured, resulting in a lower HRS. However, in the case of pulse forming, the filament is discontinuous where the transport mechanism is governed by hopping. The low resistance state （LRS） can be easily changed by removing a few trapping states from the conducting path. Hence, a higher FIRS is thus observed. However, the HRS resistance is highly dependent on the length of the gap opened. A slight variation of the gap length will cause wide dispersion of resistance.展开更多
Advances in medical devices have revolutionized the treatment of human diseases,such as stents in occluded coronary artery,left ventricular assist devices in heart failure,pacemakers in arrhythmias,etc.Despite their s...Advances in medical devices have revolutionized the treatment of human diseases,such as stents in occluded coronary artery,left ventricular assist devices in heart failure,pacemakers in arrhythmias,etc.Despite their significance,the development of devices for reducing and avoiding the thrombosis formation,obtaining excellent mechanical performance,and achieving stable electronic physiology remains challenging and unresolved.Fortunately,nature serves as a good resource of inspirations,and brings us endless bioinspired physicochemical ideas to better the development of novel artificial materials and devices that enable us to potentially overcome the unresolved obstacles.Bioinspired approaches,in particularly,owe much of their current development in biology,chemistry,materials science,medicine and engineering to the design and fabrication of advanced devices.The application of bioinspired devices is a burgeoning area in these fields of research.In this perspective,we would take the cardiovascular device as one example to show how these bioinspired approaches could be used to build novel,advanced biomedical devices with precisely controlled functions.Here,bioinspired approaches are utilized to solve issues like thrombogenic,mechanical and electronic physiology problems in medical devices.Moreover,there is an outlook for future challenges in the development of bioinspired medical devices.展开更多
The influence of a heterojunction in the vicinity of a graded BC junction on the performance of npn SiGe HBTs is studied. SiGe HBTs differing only in heterojunction position in the vicinity of a graded BC junction are...The influence of a heterojunction in the vicinity of a graded BC junction on the performance of npn SiGe HBTs is studied. SiGe HBTs differing only in heterojunction position in the vicinity of a graded BC junction are simulated by means of 2D Medici software for DC current gain and frequency characteristics. In addition, the simulated DC current gains and cut-off frequencies are compared at different collector-emitter bias voltages. Through the simulation results, both DC and HF device performance are found to be strongly impacted by degree of confinement of the neutral base in the SiGe layer, even in the absence of a conduction band barrier. This conclusion is of significance for designing and analyzing SiGe HBTs.展开更多
The method to fluorinate the terminal group has achieved remarkable success and been widely used to fine-tune the intrinsic properties of organic acceptor materials.Referring to chlorination,however,it gets less atten...The method to fluorinate the terminal group has achieved remarkable success and been widely used to fine-tune the intrinsic properties of organic acceptor materials.Referring to chlorination,however,it gets less attention and remains ambiguous effect on organic photovoltaic(OPV)cells.Herein,a new non-fullerene acceptor named Y19 was reported with benzotriazole as the electron-deficient core and 2Cl-ICs as the strong electron-withdrawing end groups.Y19 exhibits a wide film absorption band from 600 nm to 948 nm and low LUMO(the lowest unoccupied molecular orbital)energy level of−3.95 eV.Photovoltaic devices based on PM6:Y19 show high-power conversion efficiency(PCE)of 12.76%with high open-circuit voltage(Voc)of 0.84 V,short-circuit current density(Jsc)of 22.38 mA/cm2 and fill factor(FF)of 68.18%.Broad external quantum efficiency(EQE)response of over 60%in the range of 480−860 nm can be obtained.This study demonstrates that chlorination,as a low-cost molecular design strategy,has its own superiorities to improve device performance and promote the potential application in OPV.展开更多
In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After anne...In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After annealing treatment,either at elevated temperature or during slow solvent evaporation,nanoscale interpenetrating networks are formed with high crystalline order and favorable concentration gradients of both components through the thickness of the photoactive layer.Such a tailored morphology account...展开更多
The influence of different modification methods on the surface properties of indium-tin-oxide (ITO) electrodes were investigated by measurements of chemical composition,surface roughness,sheet resistance,contact angle...The influence of different modification methods on the surface properties of indium-tin-oxide (ITO) electrodes were investigated by measurements of chemical composition,surface roughness,sheet resistance,contact angle and surface free energy.Experimental results demonstrate that oxygen plasma treatment more effectively optimizes the surface properties of ITO electrodes compared with the other treatments.Furthermore,the polymer light-emitting electrochemical cells (PLECs) with the differently treated ITO substrates as device electrodes were fabricated and characterized.It is found that oxygen plasma treatment on the ITO electrode enhances injection current,luminance and efficiency,thereby improves the device characteristics of the PLECs.展开更多
Organic-inorganic hybrids are next-generation materials for use in high-performance optoelectronic devices owing to their adaptabilities in terms of design and properties.This article reviews the application of hybrid...Organic-inorganic hybrids are next-generation materials for use in high-performance optoelectronic devices owing to their adaptabilities in terms of design and properties.This article reviews the application of hybrid materials and layers in several widely used optoelectronic devices,i.e.,light amplification by stimulated emission of radiation(LASER),solar cells,and light-emitting diodes(LEDs).The effects of the incorporation of inorganic particles on photostability and optical gain are analyzed in the first section with reference to dye and perovskite lasers.Second,the strategies used in blending inorganic nanostructures into organic solar cells and bulk heterojunctions are analyzed.The use of various organic layers as electron-and hole-transport materials in Si heterojunction solar cells is reviewed in detail.Finally,the benefits of the presence of organic components in quantum-dot-and perovskite-based LEDs are derived from the analysis.The integration of organic and inorganic components with optimal interfaces and morphologies is a challenge in developing hybrid materials with improved efficiencies.展开更多
Organic fi eld-eff ect transistors(OFETs)are fabricated using organic semiconductors(OSCs)as the active layer in the form of thin fi lms.Due to its advantages of high sensitivity,low cost,compact integration,fl exibil...Organic fi eld-eff ect transistors(OFETs)are fabricated using organic semiconductors(OSCs)as the active layer in the form of thin fi lms.Due to its advantages of high sensitivity,low cost,compact integration,fl exibility,and printability,OFETs have been used extensively in the sensing area.For analysis platforms,the construction of sensing layers is a key element for their effi cient detection capability.The strategy used to immobilize biomolecules in these devices is especially important for ensuring that the sensing functions of the OFET are eff ective.Generally,analysis platforms are developed by modifying the gate/electrolyte or OSC/electrolyte interface using biomolecules,such as enzymes,antibodies,or deoxyribonucleic acid(DNA)to ensure high selectivity.To provide better or more convenient biological immobilization methods for researchers in this fi eld and thereby improve detection sensitivity,this review summarizes recent developments in the immobilization strategies used for biological macromolecules in OFETs,including cross-linking,physical adsorption,embedding,and chemical covalent binding.The infl uences of biomolecules on device performance are also discussed.展开更多
According to the good charge transporting property of perovskite, we design and simulate a p–i–n-type all-perovskite solar cell by using one-dimensional device simulator. The perovskite charge transporting layers an...According to the good charge transporting property of perovskite, we design and simulate a p–i–n-type all-perovskite solar cell by using one-dimensional device simulator. The perovskite charge transporting layers and the perovskite absorber constitute the all-perovskite cell. By modulating the cell parameters, such as layer thickness values, doping concentrations and energy bands of n-, i-, and p-type perovskite layers, the all-perovskite solar cell obtains a high power conversion efficiency of 25.84%. The band matched cell shows appreciably improved performance with widen absorption spectrum and lowered recombination rate, so weobtain a high J_（sc） of 32.47 m A/cm^2. The small series resistance of the all-perovskite solar cell also benefits the high J_（sc）. The simulation provides a novel thought of designing perovskite solar cells with simple producing process, low production cost and high efficient structure to solve the energy problem.展开更多
The porphyrin derivatives, 5,10,15,20-tetra（4-（N-pentane-carboxamide） phenyl） porphyrin（4 NC5-TPP）, 5,10,15,20-tetra（4-（N-dodecane-carboxamide） phenyl） porphyrin（4 NC12-TPP） and their zinc-complexes（4 NC5...The porphyrin derivatives, 5,10,15,20-tetra（4-（N-pentane-carboxamide） phenyl） porphyrin（4 NC5-TPP）, 5,10,15,20-tetra（4-（N-dodecane-carboxamide） phenyl） porphyrin（4 NC12-TPP） and their zinc-complexes（4 NC5-TPPZn and 4 NC12-TPPZn）, have been synthesized. Their thermal properties and morphologies were investigated via thermal gravity analysis（TGA）, differential scanning calorimetry（DSC） and polarized optical microscopy（POM）. It was found that the 4 NC5-TPP was amorphous and the 4 NC5-TPPZn was crystalline at room temperature, while the 4 NC12-TPP formed the columnar liquid crystal and the 4 NC12-TPPZn showed the spherulite texture. The electron state density distributions and the optimum configuration of the porphyrin derivatives were calculated by chemical simulation. The electrochemical oxidation and reduction abilities of the porphyrin derivatives were studied by cyclic voltammetry（CV）. It was indicated that the porphyrin derivatives had the potential to develop organic photovoltaic（OPV） devices. Using the porphyrin derivatives as donor materials and the 3,4,9,10-perylenetetracarboxylic dianhydride（PTCDA） as the acceptor material, the OPV devices were fabricated. The device structure is ITO/porphyrin derivatives：PTCDA/Al. The relationship between the morphology and performance of OPV was studied. It was found that the crystalline morphology of the film was beneficial to improve the efficiency of the devices.展开更多
Moore＇s law is approaching its physical limit. Tunneling field-effect transistors （TFETs） based on two-dimensional （2D） materials provide a possible scheme to extend Moore＇s law down to the sub-10-nm region owin...Moore＇s law is approaching its physical limit. Tunneling field-effect transistors （TFETs） based on two-dimensional （2D） materials provide a possible scheme to extend Moore＇s law down to the sub-10-nm region owing to the electrostatic integrity and absence of dangling bonds in 2D materials. We report an ab initio quantum transport study on the device performance of monolayer （ML） black phosphorene （BP） TFETs in the sub-10-nm scale （6-10 nm）. Under the optimal schemes, the ML BP TFETs show excellent device performance along the armchair transport direction. The on-state current, delay time, and power dissipation of the optimal sub-10-nm ML BP TFETs significantly surpass the latest International Technology Roadmap for Semiconductors （ITRS） requirements for high- performance devices. The subthreshold swings are 56-100 mV/dec, which are much lower than those of their Schottky barrier and metal oxide semiconductor field-effect transistor counterparts.展开更多
Electrochemical interfaces play a vital role in electrochemical energy conversion and storage.An in-depth understanding of the electrochemical interfaces is essential for developing electrochemical devices with better...Electrochemical interfaces play a vital role in electrochemical energy conversion and storage.An in-depth understanding of the electrochemical interfaces is essential for developing electrochemical devices with better performance.展开更多
Since the onset of the HIV epidemic,assessing CD4+T-cells has become a routine procedure for evaluating immune deficiency,with flow cytometry established as the gold standard.Over time,various strategies and platforms...Since the onset of the HIV epidemic,assessing CD4+T-cells has become a routine procedure for evaluating immune deficiency,with flow cytometry established as the gold standard.Over time,various strategies and platforms have been introduced to improve CD4+cell enumeration,aiming to enhance the performance of diagnostic devices and bring the service closer to patients.These advancements are particularly critical for low-resource settings and point-of-care applications,where the excellent performance of flow cytometry is hindered by its unsuitability in such environments.This work presents an innovative electrochemical microfluidic device that,with further development,could be applied for HIV management in low resource settings.The setup integrates an electrochemical sensor within a PDMS microfluidic structure,allowing for on-chip electrode functionalization and cell detection.Using electrochemical impedance spectroscopy,the biosensor demonstrates a linear detection range from 1.25×105 to 2×106 cells/mL,with a detection limit of 1.41×105 cells/mL for CD4+cells isolated from blood samples,aligning with clinical ranges for both healthy and HIV+patients.The biosensor shows specificity towards CD4+cells with negligible response to monocytes,neutrophils,and bovine serum albumin.Its integration with a microfluidic chip for sensor fabrication and cell detection,compact size,minimal manual handling,ease of fabrication,electrochemical detection capability,and potential for multiplexing together with the detection range make the device particularly advantageous for use in low-resource settings,standing out among other devices described in the literature.This study also investigates the integration of a microfluidic Dean Flow Fractionation(DFF)chip for cell separation.展开更多
基金Supported by the Science Foundation from Education Department of Liaoning Province under Grant No L2014445
文摘Native dejects in HfSiO4 are investigated by first principles calculations. Transition levels of native detects can be accurately described by employing the nonlocal HSE06 hybrid functional. This methodology overcomes the band gap problem in traditional functionals. By band alignments among the Si, GaAs and HfSiO4. we are able to determine the position of defect levels in Si and GaAs relative to the HfSiO4 band gap. We evaluate the. possibility of these defects acting as fixed charge. Native defects lead to the change of valence and conduction band offsets. Gate leakage current is evaluated by the band offset. In addition, we also investigate diffusions of native defects, and discuss how they affect the MOS device performance.
基金supported by ARO/Electronics (Grant No. W911NF-16-1-0263)the support of Bissell Distinguished Professorship at UNC-Charlotte。
文摘Despite the long history of research that has focused on the role of defects on device performance, the studies have not always been fruitful. A major reason is because these defect studies have typically been conducted in a parallel mode wherein the semiconductor wafer was divided into multiple pieces for separate optical and structural characterization, as well as device fabrication and evaluation. The major limitation of this approach was that either the defect being investigated by structural characterization techniques was not the same defect that was affecting the device performance or else the defect was not characterized under normal device operating conditions. In this review, we describe a more comprehensive approach to defect study, namely a series mode, using an array of spatially-resolved optical, electrical, and structural characterization techniques, all at the individual defect level but applied sequentially on a fabricated device. This novel sequential approach enables definitive answers to key questions, such as:(ⅰ) how do individual defects affect device performance?(ⅱ) how does the impact depend on the device operation conditions?(ⅲ) how does the impact vary from one defect to another? Implementation of this different approach is illustrated by the study of individual threading dislocation defects in GaAs solar cells. Additionally,we briefly describe a 3-D Raman thermometry method that can also be used for investigating the roles of defects in high power devices and device failure mechanisms.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0703700 and 2021YFA1200800)the National Natural Science Foundation of China(Grant Nos.91964203 and 92164103)+1 种基金the Beijing National Laboratory for Molecular Sciences(Grant No.BNLMS202001)the Fundamental Research Funds for the Central Universities(Grant No.2042021kf0029).
文摘Two-dimensional(2D)semiconductors are emerging as promising candidates for the next-generation nanoelectronics.As a type of unique channel materials,2D semiconducting transition metal dichalcogenides(TMDCs),such as MoS2 and WS2,exhibit great potential for the state-of-the-art fieldeffect transistors owing to their atomically thin thicknesses,dangling-band free surfaces,and abundant band structures.Even so,the device performances of 2D semiconducting TMDCs are still failing to reach the theoretical values so far,which is attributed to the intrinsic defects,excessive doping,and daunting contacts between electrodes and channels.In this article,we review the up-to-date three strategies for improving the device performances of 2D semiconducting TMDCs:(i)the controllable synthesis of wafer-scale 2D semiconducting TMDCs single crystals to reduce the evolution of grain boundaries,(ii)the ingenious doping of 2D semiconducting TMDCs to modulate the band structures and suppress the impurity scatterings,and(iii)the optimization design of interfacial contacts between electrodes and channels to reduce the Schottky barrier heights and contact resistances.In the end,the challenges regarding the improvement of device performances of 2D semiconducting TMDCs are highlighted,and the further research directions are also proposed.We believe that this review is comprehensive and insightful for downscaling the electronic devices and extending the Moore’s law.
基金the Beijing Natural Science Foundation of China(No.4212046)the National Natural Science Foundation of China(Nos.11704008 and 91964101)+1 种基金the Support Plan of Yuyou Youththe fund of high-level characteristic research direction from North China University of Technology.
文摘Two-dimensional(2D)semiconductors are attractive channels to shrink the scale of field-effect transistors(FETs),and among which the anisotropic one is more advantageous for a higher on-state current(I_(on)).Monolayer(ML)SnSe_(2),as an abundant,economic,nontoxic,and stable two-dimensional material,possesses an anisotropic electronic nature.Herein,we study the device performances of the ML SnSe_(2) metal-oxide-semiconductor FETs(MOSFETs)and deduce their performance limit to an ultrashort gate length(L_(g))and ultralow supply voltage(V_(dd))by using the ab initio quantum transport simulation.An ultrahigh I_(on) of 5,660 and 3,145µA/µm is acquired for the n-type 10-nm-L_(g) ML SnSe_(2) MOSFET at V_(dd)=0.7 V for high-performance(HP)and low-power(LP)applications,respectively.Specifically,until L_(g) scales down to 2 and 3 nm,the MOSFETs(at V_(dd)=0.65 V)surpass I_(on),intrinsic delay time(τ),and power-delay product(PDP)of the International Roadmap for Device and Systems(IRDS,2020 version)for HP and LP devices for the year 2028.Moreover,the 5-nm-L_(g) ML SnSe_(2) MOSFET(at V_(dd)=0.4 V)fulfills the IRDS HP device and the 7-nm-L_(g) MOSFET(at V_(dd)=0.55 V)fulfills the IRDS LP device for the year 2034.
基金supported by the National Natural Science Foundation of China(Grant Nos.61177017,61275175,61036007,61377028,and 61077022)National Science Foundation for Distinguished Young Scholars of China(Grant No.61125505)the"111" Project of China(Grant No.B08002)
文摘In this paper,the pentacene-based organic field-effect transistors(OFETs)with poly(methyl methacrylate)(PMMA)as gate dielectrics were fabricated,and the effects of gate dielectric thickness and semiconductor thickness on the device performance were investigated.The optimal PMMA thickness is in the range of 350–400 nm to sustain a considerable current density and stable performance.The device performance depends on the thicknesses of the active layer non-monotonically,which can be explained by the morphology of the pentacene film and the position of the conducting channel in the active layer.The device with a pentacene thickness of 50 nm shows the best performance,which has a maximum hole mobility of 1.12 cm2/V·s.In addition,the introduction of a thin layer of tris-(8-hydroxyquinolinato)aluminum(Alq3)to the OFETs as a light-emitting material greatly decreases the device performance.
基金Supported by the National Natural Science Foundation of China under Grant No 11365015
文摘We propose four different models of three-terminal quantum dot thermoelectric devices. From general thermodynamic laws, we examine the rew;rsible efficiencies of the four different models. Based on the master equation, the expressions for the efficiency and power output are derived and the corresponding working regions are determined. Moreover, we particularly analyze the performance of a three-terminal hybrid quantum dot refrigerator. The performance characteristic curves and the optimal performance parameters are obtained. Finally, we discuss the influence of the nonradiative effects on the optimal performance parameters in detail.
基金Supported by the Science and Technology Plan of Hunan Province under Grant No 2014SK3274
文摘We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the rotor part. When the rotor part is parallel with the stator part, a better rectifying performance can be found in the current-voltage curve. However, when the rotor part revolves to vertical with the stator part, the currents in the positive bias region decrease slightly. More importantly, the rectifying performance disappears. Thus this offers us a new method to modulate the rectifying behavior in molecular devices.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00602,2010CB934200,2011CB921804,2011CB707600,2011AA010401,and 2011AA010402the National Natural Science Foundation of China under Grant Nos61322408,61334007,61376112,61221004,61274091,61106119,61106082,and 61006011
文摘We investigate the effect of the formation process under pulse and dc modes on the performance of one transistor and one resistor （1 T1R） resistance random access memory （RRAM） device. All the devices are operated under the same test conditions, except for the initial formation process with different modes. Based on the statistical results, the high resistance state （FIRS） under the dc forming mode shows a lower value with better distribution compared with that under the pulse mode. One of the possible reasons for such a phenomenon originates from different properties of conductive filament （CF） formed in the resistive switching layer under two different modes. For the dc forming mode, the formed filament is thought to be continuous, which is hard to be ruptured, resulting in a lower HRS. However, in the case of pulse forming, the filament is discontinuous where the transport mechanism is governed by hopping. The low resistance state （LRS） can be easily changed by removing a few trapping states from the conducting path. Hence, a higher FIRS is thus observed. However, the HRS resistance is highly dependent on the length of the gap opened. A slight variation of the gap length will cause wide dispersion of resistance.
基金supported by the National Natural Science Foundation of China(Nos.21673197,31570947)Young Overseas High-level Talents Introduction Plan,the 111 Project(No.B16029)the Fundamental Research Funds for the Central Universities of China(No.20720170050)
文摘Advances in medical devices have revolutionized the treatment of human diseases,such as stents in occluded coronary artery,left ventricular assist devices in heart failure,pacemakers in arrhythmias,etc.Despite their significance,the development of devices for reducing and avoiding the thrombosis formation,obtaining excellent mechanical performance,and achieving stable electronic physiology remains challenging and unresolved.Fortunately,nature serves as a good resource of inspirations,and brings us endless bioinspired physicochemical ideas to better the development of novel artificial materials and devices that enable us to potentially overcome the unresolved obstacles.Bioinspired approaches,in particularly,owe much of their current development in biology,chemistry,materials science,medicine and engineering to the design and fabrication of advanced devices.The application of bioinspired devices is a burgeoning area in these fields of research.In this perspective,we would take the cardiovascular device as one example to show how these bioinspired approaches could be used to build novel,advanced biomedical devices with precisely controlled functions.Here,bioinspired approaches are utilized to solve issues like thrombogenic,mechanical and electronic physiology problems in medical devices.Moreover,there is an outlook for future challenges in the development of bioinspired medical devices.
文摘The influence of a heterojunction in the vicinity of a graded BC junction on the performance of npn SiGe HBTs is studied. SiGe HBTs differing only in heterojunction position in the vicinity of a graded BC junction are simulated by means of 2D Medici software for DC current gain and frequency characteristics. In addition, the simulated DC current gains and cut-off frequencies are compared at different collector-emitter bias voltages. Through the simulation results, both DC and HF device performance are found to be strongly impacted by degree of confinement of the neutral base in the SiGe layer, even in the absence of a conduction band barrier. This conclusion is of significance for designing and analyzing SiGe HBTs.
基金Project(21875286)supported by the National Natural Science Foundation of China。
文摘The method to fluorinate the terminal group has achieved remarkable success and been widely used to fine-tune the intrinsic properties of organic acceptor materials.Referring to chlorination,however,it gets less attention and remains ambiguous effect on organic photovoltaic(OPV)cells.Herein,a new non-fullerene acceptor named Y19 was reported with benzotriazole as the electron-deficient core and 2Cl-ICs as the strong electron-withdrawing end groups.Y19 exhibits a wide film absorption band from 600 nm to 948 nm and low LUMO(the lowest unoccupied molecular orbital)energy level of−3.95 eV.Photovoltaic devices based on PM6:Y19 show high-power conversion efficiency(PCE)of 12.76%with high open-circuit voltage(Voc)of 0.84 V,short-circuit current density(Jsc)of 22.38 mA/cm2 and fill factor(FF)of 68.18%.Broad external quantum efficiency(EQE)response of over 60%in the range of 480−860 nm can be obtained.This study demonstrates that chlorination,as a low-cost molecular design strategy,has its own superiorities to improve device performance and promote the potential application in OPV.
基金the research program of the Dutch Polymer Institute (DPI),project # 524.Additional financial support was provided by the Dutch Science Organization (NWO).
文摘In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After annealing treatment,either at elevated temperature or during slow solvent evaporation,nanoscale interpenetrating networks are formed with high crystalline order and favorable concentration gradients of both components through the thickness of the photoactive layer.Such a tailored morphology account...
文摘The influence of different modification methods on the surface properties of indium-tin-oxide (ITO) electrodes were investigated by measurements of chemical composition,surface roughness,sheet resistance,contact angle and surface free energy.Experimental results demonstrate that oxygen plasma treatment more effectively optimizes the surface properties of ITO electrodes compared with the other treatments.Furthermore,the polymer light-emitting electrochemical cells (PLECs) with the differently treated ITO substrates as device electrodes were fabricated and characterized.It is found that oxygen plasma treatment on the ITO electrode enhances injection current,luminance and efficiency,thereby improves the device characteristics of the PLECs.
基金M.Arya thanks the Kerala State Council for Science,Technology,and Environment,Government of Kerala,India,for providing a research fellowship(Ref.317)S.Heera thanks the Department of Science and Technology,Government of India(IF200250)for providing a research fellowship via the Innovation in Science Pursuit for Inspired Research scheme.Funding from the University Grants Commission(UGC),Government of India,via a UGC-BSR start-up grant(F.30–596/2021(BSR))is also gratefully acknowledged.
文摘Organic-inorganic hybrids are next-generation materials for use in high-performance optoelectronic devices owing to their adaptabilities in terms of design and properties.This article reviews the application of hybrid materials and layers in several widely used optoelectronic devices,i.e.,light amplification by stimulated emission of radiation(LASER),solar cells,and light-emitting diodes(LEDs).The effects of the incorporation of inorganic particles on photostability and optical gain are analyzed in the first section with reference to dye and perovskite lasers.Second,the strategies used in blending inorganic nanostructures into organic solar cells and bulk heterojunctions are analyzed.The use of various organic layers as electron-and hole-transport materials in Si heterojunction solar cells is reviewed in detail.Finally,the benefits of the presence of organic components in quantum-dot-and perovskite-based LEDs are derived from the analysis.The integration of organic and inorganic components with optimal interfaces and morphologies is a challenge in developing hybrid materials with improved efficiencies.
基金supported by the National Natural Science Foundation of China(Nos.21922409,21976131,21575100)Tianjin Research Program of Application Foundation and Advanced Technology(Nos.18JCZDJC37500,17JCYBJC20500).
文摘Organic fi eld-eff ect transistors(OFETs)are fabricated using organic semiconductors(OSCs)as the active layer in the form of thin fi lms.Due to its advantages of high sensitivity,low cost,compact integration,fl exibility,and printability,OFETs have been used extensively in the sensing area.For analysis platforms,the construction of sensing layers is a key element for their effi cient detection capability.The strategy used to immobilize biomolecules in these devices is especially important for ensuring that the sensing functions of the OFET are eff ective.Generally,analysis platforms are developed by modifying the gate/electrolyte or OSC/electrolyte interface using biomolecules,such as enzymes,antibodies,or deoxyribonucleic acid(DNA)to ensure high selectivity.To provide better or more convenient biological immobilization methods for researchers in this fi eld and thereby improve detection sensitivity,this review summarizes recent developments in the immobilization strategies used for biological macromolecules in OFETs,including cross-linking,physical adsorption,embedding,and chemical covalent binding.The infl uences of biomolecules on device performance are also discussed.
基金Project supported by the Graduate Student Education Teaching Reform Project,China(Grant No.JG201512)the Young Teachers Research Project of Yanshan University,China(Grant No.13LGB028)
文摘According to the good charge transporting property of perovskite, we design and simulate a p–i–n-type all-perovskite solar cell by using one-dimensional device simulator. The perovskite charge transporting layers and the perovskite absorber constitute the all-perovskite cell. By modulating the cell parameters, such as layer thickness values, doping concentrations and energy bands of n-, i-, and p-type perovskite layers, the all-perovskite solar cell obtains a high power conversion efficiency of 25.84%. The band matched cell shows appreciably improved performance with widen absorption spectrum and lowered recombination rate, so weobtain a high J_（sc） of 32.47 m A/cm^2. The small series resistance of the all-perovskite solar cell also benefits the high J_（sc）. The simulation provides a novel thought of designing perovskite solar cells with simple producing process, low production cost and high efficient structure to solve the energy problem.
基金Funded by the National Natural Science Foundation of China(Nos.20674022,20774031,21074039)the Natural Science Foundation of Guangdong(Nos.2006A10702003,2009B090300025,2010A090100001,2014A030313241,2014B090901068,2016A010103003)+1 种基金the Science and Technology Program of Guangdong and GuangzhouThe Ministry of Education of the People’s Republic of China(No.20090172110011)
文摘The porphyrin derivatives, 5,10,15,20-tetra（4-（N-pentane-carboxamide） phenyl） porphyrin（4 NC5-TPP）, 5,10,15,20-tetra（4-（N-dodecane-carboxamide） phenyl） porphyrin（4 NC12-TPP） and their zinc-complexes（4 NC5-TPPZn and 4 NC12-TPPZn）, have been synthesized. Their thermal properties and morphologies were investigated via thermal gravity analysis（TGA）, differential scanning calorimetry（DSC） and polarized optical microscopy（POM）. It was found that the 4 NC5-TPP was amorphous and the 4 NC5-TPPZn was crystalline at room temperature, while the 4 NC12-TPP formed the columnar liquid crystal and the 4 NC12-TPPZn showed the spherulite texture. The electron state density distributions and the optimum configuration of the porphyrin derivatives were calculated by chemical simulation. The electrochemical oxidation and reduction abilities of the porphyrin derivatives were studied by cyclic voltammetry（CV）. It was indicated that the porphyrin derivatives had the potential to develop organic photovoltaic（OPV） devices. Using the porphyrin derivatives as donor materials and the 3,4,9,10-perylenetetracarboxylic dianhydride（PTCDA） as the acceptor material, the OPV devices were fabricated. The device structure is ITO/porphyrin derivatives：PTCDA/Al. The relationship between the morphology and performance of OPV was studied. It was found that the crystalline morphology of the film was beneficial to improve the efficiency of the devices.
基金This work was supported by the Scientific Research Start-up Funding of North China University of Technology, the Youth Innovation Foundation of North China University of Technology （No.1743026）, the National Natural Science Foundation of China （Nos.11674005 and 11704008）, National Materials Genome Project （No. 2016YFB0700601）, and the National Basic Research Program of China （No. 2013CB932604）.
文摘Moore＇s law is approaching its physical limit. Tunneling field-effect transistors （TFETs） based on two-dimensional （2D） materials provide a possible scheme to extend Moore＇s law down to the sub-10-nm region owing to the electrostatic integrity and absence of dangling bonds in 2D materials. We report an ab initio quantum transport study on the device performance of monolayer （ML） black phosphorene （BP） TFETs in the sub-10-nm scale （6-10 nm）. Under the optimal schemes, the ML BP TFETs show excellent device performance along the armchair transport direction. The on-state current, delay time, and power dissipation of the optimal sub-10-nm ML BP TFETs significantly surpass the latest International Technology Roadmap for Semiconductors （ITRS） requirements for high- performance devices. The subthreshold swings are 56-100 mV/dec, which are much lower than those of their Schottky barrier and metal oxide semiconductor field-effect transistor counterparts.
文摘Electrochemical interfaces play a vital role in electrochemical energy conversion and storage.An in-depth understanding of the electrochemical interfaces is essential for developing electrochemical devices with better performance.
基金funding from Santander postgraduate mobility awards and Department of Electronic&Electrical Engineering,University of BathR.S.was funded through UK Engineering and Physical Sciences Research Council grant number EP/V040189/1.
文摘Since the onset of the HIV epidemic,assessing CD4+T-cells has become a routine procedure for evaluating immune deficiency,with flow cytometry established as the gold standard.Over time,various strategies and platforms have been introduced to improve CD4+cell enumeration,aiming to enhance the performance of diagnostic devices and bring the service closer to patients.These advancements are particularly critical for low-resource settings and point-of-care applications,where the excellent performance of flow cytometry is hindered by its unsuitability in such environments.This work presents an innovative electrochemical microfluidic device that,with further development,could be applied for HIV management in low resource settings.The setup integrates an electrochemical sensor within a PDMS microfluidic structure,allowing for on-chip electrode functionalization and cell detection.Using electrochemical impedance spectroscopy,the biosensor demonstrates a linear detection range from 1.25×105 to 2×106 cells/mL,with a detection limit of 1.41×105 cells/mL for CD4+cells isolated from blood samples,aligning with clinical ranges for both healthy and HIV+patients.The biosensor shows specificity towards CD4+cells with negligible response to monocytes,neutrophils,and bovine serum albumin.Its integration with a microfluidic chip for sensor fabrication and cell detection,compact size,minimal manual handling,ease of fabrication,electrochemical detection capability,and potential for multiplexing together with the detection range make the device particularly advantageous for use in low-resource settings,standing out among other devices described in the literature.This study also investigates the integration of a microfluidic Dean Flow Fractionation(DFF)chip for cell separation.
