The instability of plasma waves in the channel of field-effect transistors will cause the electromagnetic waves with THz frequency.Based on a self-consistent quantum hydrodynamic model,the instability of THz plasmas w...The instability of plasma waves in the channel of field-effect transistors will cause the electromagnetic waves with THz frequency.Based on a self-consistent quantum hydrodynamic model,the instability of THz plasmas waves in the channel of graphene field-effect transistors has been investigated with external magnetic field and quantum effects.We analyzed the influence of weak magnetic fields,quantum effects,device size,and temperature on the instability of plasma waves under asymmetric boundary conditions numerically.The results show that the magnetic fields,quantum effects,and the thickness of the dielectric layer between the gate and the channel can increase the radiation frequency.Additionally,we observed that increase in temperature leads to a decrease in both oscillation frequency and instability increment.The numerical results and accompanying images obtained from our simulations provide support for the above conclusions.展开更多
Flexible electronics are transforming our lives by making daily activities more convenient.Central to this innovation are field-effect transistors(FETs),valued for their efficient signal processing,nanoscale fabricati...Flexible electronics are transforming our lives by making daily activities more convenient.Central to this innovation are field-effect transistors(FETs),valued for their efficient signal processing,nanoscale fabrication,low-power consumption,fast response times,and versatility.Graphene,known for its exceptional mechanical properties,high electron mobility,and biocompatibility,is an ideal material for FET channels and sensors.The combination of graphene and FETs has given rise to flexible graphene field-effect transistors(FGFETs),driving significant advances in flexible electronics and sparked a strong interest in flexible biomedical sensors.Here,we first provide a brief overview of the basic structure,operating mechanism,and evaluation parameters of FGFETs,and delve into their material selection and patterning techniques.The ability of FGFETs to sense strains and biomolecular charges opens up diverse application possibilities.We specifically analyze the latest strategies for integrating FGFETs into wearable and implantable flexible biomedical sensors,focusing on the key aspects of constructing high-quality flexible biomedical sensors.Finally,we discuss the current challenges and prospects of FGFETs and their applications in biomedical sensors.This review will provide valuable insights and inspiration for ongoing research to improve the quality of FGFETs and broaden their application prospects in flexible biomedical sensing.展开更多
Graphene has attracted enormous interests due to its unique physical, mechanical, and electrical properties. Specially, graphene-based field-effect transistors （FETs） have evolved rapidly and are now considered as a...Graphene has attracted enormous interests due to its unique physical, mechanical, and electrical properties. Specially, graphene-based field-effect transistors （FETs） have evolved rapidly and are now considered as an option for conventional silicon devices. As a critical step in the design cycle of modem IC products, compact model refers to the development of models for integrated semiconductor devices for use in circuit simulations. The purpose of this review is to provide a theoretical description of current compact model of graphene field-effect transistors. Special attention is devoted to the charge sheet model, drift-diffusion model, Boltzmann equation, density of states （DOS）, and surface-potential-based compact model. Finally, an outlook of this field is briefly discussed.展开更多
Monolayer and bilayer graphenes have generated tremendous excitement as the potentially useful electronic materials due to their unique features. We report on monolayer and bilayer epitaxial graphene field-effect tran...Monolayer and bilayer graphenes have generated tremendous excitement as the potentially useful electronic materials due to their unique features. We report on monolayer and bilayer epitaxial graphene field-effect transistors （GFETs） fabricated on SiC substrates. Compared with monolayer GFETs, the bilayer GFETs exhibit a significant improvement in dc characteristics, including increasing current density I DS, improved transconductance g m, reduced sheet resistance lion, and current saturation. The improved electrical properties and tunable bandgap in the bilayer graphene lead to the excellent dc performance of the bilayer GFETs. Furthermore, the improved dc characteristics enhance a better rf performance for bilayer graphene devices, demonstrating that the quasifree-standing bilayer graphene on SiC substrates has a great application potential for the future graphene-based electronics.展开更多
In this paper,high temperature direct current（DC） performance of bilayer epitaxial graphene device on SiC substrate is studied in a temperature range from 25℃ to 200℃.At a gate voltage of-8 V（far from Dirac point...In this paper,high temperature direct current（DC） performance of bilayer epitaxial graphene device on SiC substrate is studied in a temperature range from 25℃ to 200℃.At a gate voltage of-8 V（far from Dirac point）,the drainsource current decreases obviously with increasing temperature,but it has little change at a gate bias of ＋8 V（near Dirac point）.The competing interactions between scattering and thermal activation are responsible for the different reduction tendencies.Four different kinds of scatterings are taken into account to qualitatively analyze the carrier mobility under different temperatures.The devices exhibit almost unchanged DC performances after high temperature measurements at 200℃ for 5 hours in air ambience,demonstrating the high thermal stabilities of the bilayer epitaxial graphene devices.展开更多
Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and requi...Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and require different consider- ations. The unique band structure of graphene necessitates engineering of the Dirac point, including the opening of the bandgap, the doping and the interface, before the graphene can be used in logic applications. On the other hand, MoS2 is a semiconductor, and its electron transport depends heavily on the surface properties, the number of layers, and the carrier density. Finally, we discuss the prospects for the future developments in 2D material transistors.展开更多
Nitrogen doping is a promising way to modulate the electrical properties of graphene to realize graphene-based electronics and promise fascinating properties and applications.Herein,we report a method to noncovalently...Nitrogen doping is a promising way to modulate the electrical properties of graphene to realize graphene-based electronics and promise fascinating properties and applications.Herein,we report a method to noncovalently assembly titanium(Ⅳ) bis(ammoniumlactato) dihydroxide(Ti complex) on nitrogen-doped graphene to create a reliable hybrids which can be used as a reversible chemical induced switching.As the adsorption and desorption of Ti complex in sequential treatments,the conductance of the nitrogen-doped graphene transistors was finely modulated.Control experiments with pristine graphene clearly demonstrated the important effort of the nitrogen in this chemical sensor.Under optimized conditions,nitrogen-doped graphene transistors open up new ways to develop multifunctional devices with high sensitivity.展开更多
We report on a demonstration of top-gated graphene field-effect transistors(FETs) fabricated on epitaxial SiC substrate.Composite stacks,benzocyclobutene and atomic layer deposition Al2O3,are used as the gate dielectr...We report on a demonstration of top-gated graphene field-effect transistors(FETs) fabricated on epitaxial SiC substrate.Composite stacks,benzocyclobutene and atomic layer deposition Al2O3,are used as the gate dielectrics to maintain intrinsic carrier mobility of graphene.All graphene FETs exhibit n-type transistor characteristics and the drain current is nearly linear dependence on gate and drain voltages.Despite a low field-effect mobility of 40 cm2/(V s),a maximum cutoff frequency of 4.6 GHz and a maximum oscillation frequency of 1.5 GHz were obtained for the graphene devices with a gate length of 1 μm.展开更多
In recent years,graphene field-effect-transistors(GFETs)have demonstrated an outstanding potential for terahertz(THz)photodetection due to their fast response and high-sensitivity.Such features are essential to enable...In recent years,graphene field-effect-transistors(GFETs)have demonstrated an outstanding potential for terahertz(THz)photodetection due to their fast response and high-sensitivity.Such features are essential to enable emerging THz applications,including 6G wireless communications,quantum information,bioimaging and security.However,the overall performance of these photodetectors may be utterly compromised by the impact of internal resistances presented in the device,so-called access or parasitic resistances.In this work,we provide a detailed study of the influence of internal device resistances in the photoresponse of high-mobility dual-gate GFET detectors.Such dual-gate architectures allow us to fine tune(decrease)the internal resistance of the device by an order of magnitude and consequently demonstrate an improved responsivity and noise-equivalent-power values of the photodetector,respectively.Our results can be well understood by a series resistance model,as shown by the excellent agreement found between the experimental data and theoretical calculations.These findings are therefore relevant to understand and improve the overall performance of existing high-mobility graphene photodetectors.展开更多
We report the fabrication of a highly sensitive field-effect transistor （FET） biosensor using thermally-reduced graphene oxide （TRGO） sheets functionalized with gold nanoparticle （NP）-antibody conjugates. Probe ...We report the fabrication of a highly sensitive field-effect transistor （FET） biosensor using thermally-reduced graphene oxide （TRGO） sheets functionalized with gold nanoparticle （NP）-antibody conjugates. Probe antibody was labeled on the surface of TRGO sheets through Au NPs and electrical detection of protein binding （Immunoglobulin G/IgG and anti-lmmunoglobulin G/anti-lgG） was accomplished by FET and direct current （dc） measurements. The protein binding events induced significant changes in the resistance of the TRGO sheet, which is referred to as the sensor response. The dependence of the sensor response on the TRGO base resistance in the sensor and the antibody areal density on the TRGO sheet was systematically studied, from which a correlation of the sensor response with sensor parameters was found： the sensor response was more significant with larger TRGO base resistance and higher antibody areal density. The detection limit of the novel biosensor was around the 0.2 ng/rnL level, which is among the best of,＇eported carbon nanomaterial-based protein sensors and can be further optimized by tuning the sensor structure.展开更多
Realizing low contact resistance between graphene and metal electrodes remains a well-known challenge for building high-performance graphene devices. In this work, we attempt to reduce the contact resistance in graphe...Realizing low contact resistance between graphene and metal electrodes remains a well-known challenge for building high-performance graphene devices. In this work, we attempt to reduce the contact resistance in graphene transistors and further explore the resistance limit between graphene and metal contacts. The Pd/graphene contact resistance at room temperature is reduced below the 100 Ω·μm level both on mechanically exfoliated and chemical-vapor-deposition graphene by adopting high-purity palladium and high-quality graphene and controlling the fabrication process to not contaminate the interface. After excluding the parasitic series resistances from the measurement system and electrodes, the retrieved contact resistance is shown to be systematically and statistically less than 100 Ω·μm, with a minimum value of 69 Ω·μm, which is very close to the theoretical limit. Furthermore, the contact resistance shows no clear dependence on temperature in the range of 77-300 K; this is attributed to the saturation of carrier injection efficiency between graphene and Pd owing to the high quality of the graphene samples used, which have a sufficiently long carrier mean-free-path.展开更多
It is promising to apply quantum-mechanically confined graphene systems in field-effect transistors. High stability, superior performance, and large-scale integration are the main challenges facing the practical appli...It is promising to apply quantum-mechanically confined graphene systems in field-effect transistors. High stability, superior performance, and large-scale integration are the main challenges facing the practical application of graphene transistors. Our understandings of the adatom-graphene interac- tion combined with recent progress in the nanofabrication technology indicate that very stable and high-quality graphene nanostripes could be integrated in substrate-supported functionalized （hydro- genated or fluorinated） graphene using electron-beam lithography. We also propose that parallelizing a couple of graphene nanostripes in a transistor should be preferred for practical application, which is also very useful for transistors based on graphene nanoribbon.展开更多
We present a semi-analytical model incorporating the effects of edge bond relaxation,the third nearest neighbor interactions,and edge scattering in graphene nanoribbon fi eld-effect transistors(GNRFETs)with armchair-e...We present a semi-analytical model incorporating the effects of edge bond relaxation,the third nearest neighbor interactions,and edge scattering in graphene nanoribbon fi eld-effect transistors(GNRFETs)with armchair-edge GNR(AGNR)channels.Unlike carbon nanotubes(CNTs)which do not have edges,the existence of edges in the AGNRs has a signifi cant effect on the quantum capacitance and ballistic I V characteristics of GNRFETs.For an AGNR with an index of m=3p,the band gap decreases and the ON current increases whereas for an AGNR with an index of m=3p+1,the quantum capacitance increases and the ON current decreases.The effect of edge scattering,which reduces the ON current,is also included in the model.展开更多
Layer-number modulation in graphene has become a recent focus of research due to the superior degree of freedom that can be achieved in terms of magic-angle,wettability,superconductivity,and superlattices.However,the ...Layer-number modulation in graphene has become a recent focus of research due to the superior degree of freedom that can be achieved in terms of magic-angle,wettability,superconductivity,and superlattices.However,the intrinsic transport of multilayer graphene is indistinguishable in atmospheric adsorbates and supporting environment,and its underlying charge transfer mechanism has not yet been thoroughly determined.In this study,a shift in the charge neutrality point of trilayer graphene(TLG)is demonstrated to be regulated by three governing factors:oxygen gas(O_(2)),water molecules(H_(2)O),and thermally activated electrons.Absorbed O_(2) induces a high work function in semimetallic TLG,while H_(2)O is not an evident dopant but can strengthen binding against O_(2) desorption.A simplified model is developed to elucidate the competitive mechanism and charge transfer among these two dopants(O_(2),H_(2)O)and thermal electrons,and the model is demonstrated by work function regulation and Bader charge transfer based on density functional theory calculations.This study provides a strategy to explore transport modulation of multilayer graphene in the fields of ballistic transport and low power consumption of graphene field-effect transistors.展开更多
Monitoring taste-inducing ions and molecules continuously in liquids or solutions is of great considerable matter for the realization of the electronic tongue(E-tongue).Particularly from the five major tastes,the high...Monitoring taste-inducing ions and molecules continuously in liquids or solutions is of great considerable matter for the realization of the electronic tongue(E-tongue).Particularly from the five major tastes,the highly selective,sensitive detection of Na^(+)in real-time is prioritized.Prioritization is due to the saltiness of food is the key ingredient in most meals.Nevertheless,existing Na^(+)detecting devices have relatively low performances of selectivity,sensitivity,and lack of on–off functions.Additionally,conventional devices significantly deteriorate in capac-ity due to repetitive usage or lifetime shortage by degradation of the sensing mate-rial.Herein,a graphene-based channel was rationally designed by the facile decoration of Calix[4]arene and Nafion to address this issue.They act as a receptor and a molecular sieve,respectively,to enhance selectivity and sensitivity and elon-gate the life expectancy of the device.This device was merged with a microfluidic channel to control the injection and withdrawal of solutions to fulfill dynamic on–off functions.The fabricated device has highly selective,sensitive Na^(+)detection properties compared to other 10 molecule/ionic species.Dynamic on–off functions of the device were available,also possesses a long lifespan of at least 220 days.Additionally,it can precisely discriminate real beverages containing Na^(+),which can be observed by principal component analysis plot.These features offer the possibility of ascending to a platform for E-tongues in near future.展开更多
The performance limits of a multilayer graphene nanoribbon(GNR)field-effect transistor(FET)are assessed and compared with those of a monolayer GNRFET and a carbon nanotube(CNT)FET.The results show that with a thin hig...The performance limits of a multilayer graphene nanoribbon(GNR)field-effect transistor(FET)are assessed and compared with those of a monolayer GNRFET and a carbon nanotube(CNT)FET.The results show that with a thin high dielectric constant(high-κ)gate insulator and reduced interlayer coupling,a multilayer GNRFET can significantly outperform its CNT counterpart with a similar gate and bandgap in terms of the ballistic on-current.In the presence of optical phonon scattering,which has a short mean free path in the graphene-derived nanostructures,the advantage of the multilayer GNRFET is even more significant.Simulation results indicate that multilayer GNRs with incommensurate non-AB stacking and weak interlayer coupling are the best candidates for high-performance GNRFETs.展开更多
Diabetes is a chronic metabolic disease that has effect on blood sugar level and affects millions of people.We present an integrated flexible and reusable graphene-based field effect transistor(GFET)nanosensor for the...Diabetes is a chronic metabolic disease that has effect on blood sugar level and affects millions of people.We present an integrated flexible and reusable graphene-based field effect transistor(GFET)nanosensor for the detection of glucose using pyrene-1-boronic acid(PBA)as the receptor.The nanosensor fabricated on the polyimide performs GFET-based rapid transduction of the glucose-PBA binding,thereby potentially allowing the detection of glucose that are sampled reliably from human bodily fluids(e.g.,sweat)in wearable sensing applications.Due to the reversible binding interaction between PBA and glucose,reusability of our nanosensor can be realized by exposing graphene surface to acidic solution.In characterizing the stability and reusability of the nanosensor for wearable applications,we investigated the effects of substrate bending,multiple reuse and long-time storage on the equilibrium dissociation constant between the PBA and glucose.Results show that bending,multiple reuse(over 10 times)and long-time storage has negligible effect on the sensing performance.The detection of glucose with a limit of detection(LOD)of 0.15 μM and a dynamic range of 0.05-100 μM,which covers the reference scope of physical examination or screening of diabetes.Hence,our flexible GFET nanosensor is promising for wearable and reusable biosensing applications.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.12065015)the Hongliu Firstlevel Discipline Construction Project of Lanzhou University of Technology。
文摘The instability of plasma waves in the channel of field-effect transistors will cause the electromagnetic waves with THz frequency.Based on a self-consistent quantum hydrodynamic model,the instability of THz plasmas waves in the channel of graphene field-effect transistors has been investigated with external magnetic field and quantum effects.We analyzed the influence of weak magnetic fields,quantum effects,device size,and temperature on the instability of plasma waves under asymmetric boundary conditions numerically.The results show that the magnetic fields,quantum effects,and the thickness of the dielectric layer between the gate and the channel can increase the radiation frequency.Additionally,we observed that increase in temperature leads to a decrease in both oscillation frequency and instability increment.The numerical results and accompanying images obtained from our simulations provide support for the above conclusions.
基金supported by the National Key R&D Plan of China(Grant No.2023YFB3210400)the National Natural Science Foundation of China(No.62174101)+2 种基金the Major Scientific and Technological Innovation Project of Shandong Province(2021CXGC010603)the Fundamental Research Funds of Shandong University(2020QNQT001)Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong,Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong,the Natural Science Foundation of Qingdao-Original exploration project(No.24-4-4-zrjj-139-jch).
文摘Flexible electronics are transforming our lives by making daily activities more convenient.Central to this innovation are field-effect transistors(FETs),valued for their efficient signal processing,nanoscale fabrication,low-power consumption,fast response times,and versatility.Graphene,known for its exceptional mechanical properties,high electron mobility,and biocompatibility,is an ideal material for FET channels and sensors.The combination of graphene and FETs has given rise to flexible graphene field-effect transistors(FGFETs),driving significant advances in flexible electronics and sparked a strong interest in flexible biomedical sensors.Here,we first provide a brief overview of the basic structure,operating mechanism,and evaluation parameters of FGFETs,and delve into their material selection and patterning techniques.The ability of FGFETs to sense strains and biomolecular charges opens up diverse application possibilities.We specifically analyze the latest strategies for integrating FGFETs into wearable and implantable flexible biomedical sensors,focusing on the key aspects of constructing high-quality flexible biomedical sensors.Finally,we discuss the current challenges and prospects of FGFETs and their applications in biomedical sensors.This review will provide valuable insights and inspiration for ongoing research to improve the quality of FGFETs and broaden their application prospects in flexible biomedical sensing.
基金Project supported by the Opening Project of Key Laboratory of Microelectronics Devices and Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences,the National Natural Science Foundation of China(Grant No.61574166)the National Basic Research Program of China(Grant No.2013CBA01604)+1 种基金the National Key Research and Development Program of China(Grant No.2016YFA0201802)and the Beijing Training Project for the Leading Talents in S&T,China(Grant No.Z151100000315008)
文摘Graphene has attracted enormous interests due to its unique physical, mechanical, and electrical properties. Specially, graphene-based field-effect transistors （FETs） have evolved rapidly and are now considered as an option for conventional silicon devices. As a critical step in the design cycle of modem IC products, compact model refers to the development of models for integrated semiconductor devices for use in circuit simulations. The purpose of this review is to provide a theoretical description of current compact model of graphene field-effect transistors. Special attention is devoted to the charge sheet model, drift-diffusion model, Boltzmann equation, density of states （DOS）, and surface-potential-based compact model. Finally, an outlook of this field is briefly discussed.
基金Supported by the National Natural Science Foundation of China under Grant No 61306006
文摘Monolayer and bilayer graphenes have generated tremendous excitement as the potentially useful electronic materials due to their unique features. We report on monolayer and bilayer epitaxial graphene field-effect transistors （GFETs） fabricated on SiC substrates. Compared with monolayer GFETs, the bilayer GFETs exhibit a significant improvement in dc characteristics, including increasing current density I DS, improved transconductance g m, reduced sheet resistance lion, and current saturation. The improved electrical properties and tunable bandgap in the bilayer graphene lead to the excellent dc performance of the bilayer GFETs. Furthermore, the improved dc characteristics enhance a better rf performance for bilayer graphene devices, demonstrating that the quasifree-standing bilayer graphene on SiC substrates has a great application potential for the future graphene-based electronics.
基金Project supported by the National Natural Science Foundation of China(Grant No.61306006)
文摘In this paper,high temperature direct current（DC） performance of bilayer epitaxial graphene device on SiC substrate is studied in a temperature range from 25℃ to 200℃.At a gate voltage of-8 V（far from Dirac point）,the drainsource current decreases obviously with increasing temperature,but it has little change at a gate bias of ＋8 V（near Dirac point）.The competing interactions between scattering and thermal activation are responsible for the different reduction tendencies.Four different kinds of scatterings are taken into account to qualitatively analyze the carrier mobility under different temperatures.The devices exhibit almost unchanged DC performances after high temperature measurements at 200℃ for 5 hours in air ambience,demonstrating the high thermal stabilities of the bilayer epitaxial graphene devices.
基金supported by the National Basic Research Program of China (Grant No. 2013CBA01600)the National Natural Science Foundation of China (Grant Nos. 61261160499 and 11274154)+2 种基金the National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2011ZX02707)the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2012302)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120091110028)
文摘Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and require different consider- ations. The unique band structure of graphene necessitates engineering of the Dirac point, including the opening of the bandgap, the doping and the interface, before the graphene can be used in logic applications. On the other hand, MoS2 is a semiconductor, and its electron transport depends heavily on the surface properties, the number of layers, and the carrier density. Finally, we discuss the prospects for the future developments in 2D material transistors.
文摘Nitrogen doping is a promising way to modulate the electrical properties of graphene to realize graphene-based electronics and promise fascinating properties and applications.Herein,we report a method to noncovalently assembly titanium(Ⅳ) bis(ammoniumlactato) dihydroxide(Ti complex) on nitrogen-doped graphene to create a reliable hybrids which can be used as a reversible chemical induced switching.As the adsorption and desorption of Ti complex in sequential treatments,the conductance of the nitrogen-doped graphene transistors was finely modulated.Control experiments with pristine graphene clearly demonstrated the important effort of the nitrogen in this chemical sensor.Under optimized conditions,nitrogen-doped graphene transistors open up new ways to develop multifunctional devices with high sensitivity.
基金supported by the National Science and Technology Major Project(2011ZX02707.3)the National Basic Research Program of China(2011CB932700)the National Natural Science Foundation of China(61136005,50972162,51072223 and 61006063)
文摘We report on a demonstration of top-gated graphene field-effect transistors(FETs) fabricated on epitaxial SiC substrate.Composite stacks,benzocyclobutene and atomic layer deposition Al2O3,are used as the gate dielectrics to maintain intrinsic carrier mobility of graphene.All graphene FETs exhibit n-type transistor characteristics and the drain current is nearly linear dependence on gate and drain voltages.Despite a low field-effect mobility of 40 cm2/(V s),a maximum cutoff frequency of 4.6 GHz and a maximum oscillation frequency of 1.5 GHz were obtained for the graphene devices with a gate length of 1 μm.
基金support from the Ministry of Science and Innovation(MCIN)and the Spanish State Research Agency(AEI)under grants(PID2021-126483OB-I00,PID2021-128154NA-I00 and PID2022-136285NB-C32)funded by MICIU/AEI/https://doi.org/10.13039/501100011033 and by“ERDF A way of making Europe.”This work has been also supported by Junta de Castilla y Leon co-funded by FEDER under the Research Grant numbers SA103P23 and SA106P23+3 种基金KW and TT acknowledge support from the JSPS KAKENHI(Grant Numbers 21H05233 and 23H02052)and World Premier International Research Center Initiative(WPI),MEXT,JapanJMC acknowledges financial support by the MCIN and AEI“Ramon y Cajal”program(RYC2019-028443-I)funded by MICIU/AEI/https://doi.org/10.13039/501100011033 and by“ESF Investing in Your Future.”JMC also acknowledges financial of the European Research Council(ERC)under Starting grant ID 101039754,CHIROTRONICS,funded by the European UnionJAD-N thanks the support from the Universidad de Salamanca for the Maria Zambrano postdoctoral grant funded by the Next Generation EU Funding for the Requalification of the Spanish University System 2021-23,Spanish Ministry of Universities.ies.
文摘In recent years,graphene field-effect-transistors(GFETs)have demonstrated an outstanding potential for terahertz(THz)photodetection due to their fast response and high-sensitivity.Such features are essential to enable emerging THz applications,including 6G wireless communications,quantum information,bioimaging and security.However,the overall performance of these photodetectors may be utterly compromised by the impact of internal resistances presented in the device,so-called access or parasitic resistances.In this work,we provide a detailed study of the influence of internal device resistances in the photoresponse of high-mobility dual-gate GFET detectors.Such dual-gate architectures allow us to fine tune(decrease)the internal resistance of the device by an order of magnitude and consequently demonstrate an improved responsivity and noise-equivalent-power values of the photodetector,respectively.Our results can be well understood by a series resistance model,as shown by the excellent agreement found between the experimental data and theoretical calculations.These findings are therefore relevant to understand and improve the overall performance of existing high-mobility graphene photodetectors.
基金Financial support for this work was provided by the USA National Science Foundation （NSF） （Nos. CMMI- 0900509, CBET-0803142, and ECCS-0708998）. Graphene oxide samples were supplied by Prof. Rodney S. Ruoff. The authors thank Dr. Heather A. Owen for technical support with SEM, and Dr. Leonidas E. Ocola for assistance in the electrode fabrication. The e-beam lithography was performed at the Center for Nanoscale Materials of Argonne National Laboratory, which is supported by the USA Department of Energy （No. DE- AC02-06CH11357）. The SEM imaging was conducted at the Electron Microscope Laboratory of University of Wisconsin-Milwaukee.
文摘We report the fabrication of a highly sensitive field-effect transistor （FET） biosensor using thermally-reduced graphene oxide （TRGO） sheets functionalized with gold nanoparticle （NP）-antibody conjugates. Probe antibody was labeled on the surface of TRGO sheets through Au NPs and electrical detection of protein binding （Immunoglobulin G/IgG and anti-lmmunoglobulin G/anti-lgG） was accomplished by FET and direct current （dc） measurements. The protein binding events induced significant changes in the resistance of the TRGO sheet, which is referred to as the sensor response. The dependence of the sensor response on the TRGO base resistance in the sensor and the antibody areal density on the TRGO sheet was systematically studied, from which a correlation of the sensor response with sensor parameters was found： the sensor response was more significant with larger TRGO base resistance and higher antibody areal density. The detection limit of the novel biosensor was around the 0.2 ng/rnL level, which is among the best of,＇eported carbon nanomaterial-based protein sensors and can be further optimized by tuning the sensor structure.
基金This work was supported by the Ministry of Sdence and Technology of China （Grant Nos. 2011CB933001 and 2011CB933002）, National Natural Science Foundation of China （Grant Nos. 61322105, 61271051, 61321001, and 61390504）, and Beijing Municipal Science and Technology Commission （Grant Nos. Z131100003213021 and D141100000614001）.
文摘Realizing low contact resistance between graphene and metal electrodes remains a well-known challenge for building high-performance graphene devices. In this work, we attempt to reduce the contact resistance in graphene transistors and further explore the resistance limit between graphene and metal contacts. The Pd/graphene contact resistance at room temperature is reduced below the 100 Ω·μm level both on mechanically exfoliated and chemical-vapor-deposition graphene by adopting high-purity palladium and high-quality graphene and controlling the fabrication process to not contaminate the interface. After excluding the parasitic series resistances from the measurement system and electrodes, the retrieved contact resistance is shown to be systematically and statistically less than 100 Ω·μm, with a minimum value of 69 Ω·μm, which is very close to the theoretical limit. Furthermore, the contact resistance shows no clear dependence on temperature in the range of 77-300 K; this is attributed to the saturation of carrier injection efficiency between graphene and Pd owing to the high quality of the graphene samples used, which have a sufficiently long carrier mean-free-path.
文摘It is promising to apply quantum-mechanically confined graphene systems in field-effect transistors. High stability, superior performance, and large-scale integration are the main challenges facing the practical application of graphene transistors. Our understandings of the adatom-graphene interac- tion combined with recent progress in the nanofabrication technology indicate that very stable and high-quality graphene nanostripes could be integrated in substrate-supported functionalized （hydro- genated or fluorinated） graphene using electron-beam lithography. We also propose that parallelizing a couple of graphene nanostripes in a transistor should be preferred for practical application, which is also very useful for transistors based on graphene nanoribbon.
基金This work was supported in part by the Office of Naval Research grant N000140810861in part by NSF grants ECCS-0824157 and CCF-0701547.
文摘We present a semi-analytical model incorporating the effects of edge bond relaxation,the third nearest neighbor interactions,and edge scattering in graphene nanoribbon fi eld-effect transistors(GNRFETs)with armchair-edge GNR(AGNR)channels.Unlike carbon nanotubes(CNTs)which do not have edges,the existence of edges in the AGNRs has a signifi cant effect on the quantum capacitance and ballistic I V characteristics of GNRFETs.For an AGNR with an index of m=3p,the band gap decreases and the ON current increases whereas for an AGNR with an index of m=3p+1,the quantum capacitance increases and the ON current decreases.The effect of edge scattering,which reduces the ON current,is also included in the model.
基金supported by the National Natural Science Foundation of China(Nos.12064047,11864044,11704330,and 11564043)the Key and General Program of Yunnan Fundamental Research Projects(Nos.202101AS070046 and 202001BB050051)The model software in this work is the Device Studio software package from Hongzhiwei.
文摘Layer-number modulation in graphene has become a recent focus of research due to the superior degree of freedom that can be achieved in terms of magic-angle,wettability,superconductivity,and superlattices.However,the intrinsic transport of multilayer graphene is indistinguishable in atmospheric adsorbates and supporting environment,and its underlying charge transfer mechanism has not yet been thoroughly determined.In this study,a shift in the charge neutrality point of trilayer graphene(TLG)is demonstrated to be regulated by three governing factors:oxygen gas(O_(2)),water molecules(H_(2)O),and thermally activated electrons.Absorbed O_(2) induces a high work function in semimetallic TLG,while H_(2)O is not an evident dopant but can strengthen binding against O_(2) desorption.A simplified model is developed to elucidate the competitive mechanism and charge transfer among these two dopants(O_(2),H_(2)O)and thermal electrons,and the model is demonstrated by work function regulation and Bader charge transfer based on density functional theory calculations.This study provides a strategy to explore transport modulation of multilayer graphene in the fields of ballistic transport and low power consumption of graphene field-effect transistors.
基金National R&D Program,Grant/Award Number:2021M3H4A3A02086430Nano Material Technology Development Program,Grant/Award Number:2022M3H4A1A01011993+3 种基金Ministry of Science and ICT,South KoreaResearch Institute of Advanced Materials(RIAM)Inter University Semiconductor Research Center(ISRC)National Instrumentation Center for Environmental Management(NICEM)。
文摘Monitoring taste-inducing ions and molecules continuously in liquids or solutions is of great considerable matter for the realization of the electronic tongue(E-tongue).Particularly from the five major tastes,the highly selective,sensitive detection of Na^(+)in real-time is prioritized.Prioritization is due to the saltiness of food is the key ingredient in most meals.Nevertheless,existing Na^(+)detecting devices have relatively low performances of selectivity,sensitivity,and lack of on–off functions.Additionally,conventional devices significantly deteriorate in capac-ity due to repetitive usage or lifetime shortage by degradation of the sensing mate-rial.Herein,a graphene-based channel was rationally designed by the facile decoration of Calix[4]arene and Nafion to address this issue.They act as a receptor and a molecular sieve,respectively,to enhance selectivity and sensitivity and elon-gate the life expectancy of the device.This device was merged with a microfluidic channel to control the injection and withdrawal of solutions to fulfill dynamic on–off functions.The fabricated device has highly selective,sensitive Na^(+)detection properties compared to other 10 molecule/ionic species.Dynamic on–off functions of the device were available,also possesses a long lifespan of at least 220 days.Additionally,it can precisely discriminate real beverages containing Na^(+),which can be observed by principal component analysis plot.These features offer the possibility of ascending to a platform for E-tongues in near future.
基金This work was supported by the National Science Foundation(NSF)and the Office of Naval Research(ONR),Intel,and MARCO MSD.
文摘The performance limits of a multilayer graphene nanoribbon(GNR)field-effect transistor(FET)are assessed and compared with those of a monolayer GNRFET and a carbon nanotube(CNT)FET.The results show that with a thin high dielectric constant(high-κ)gate insulator and reduced interlayer coupling,a multilayer GNRFET can significantly outperform its CNT counterpart with a similar gate and bandgap in terms of the ballistic on-current.In the presence of optical phonon scattering,which has a short mean free path in the graphene-derived nanostructures,the advantage of the multilayer GNRFET is even more significant.Simulation results indicate that multilayer GNRs with incommensurate non-AB stacking and weak interlayer coupling are the best candidates for high-performance GNRFETs.
基金supported by fundings from the National Natural Science Foundation of China(Grant Nos.51505108)the Heilongjiang Postdoctoral Science Foundation(Grant Nos.LBHZ19221)+1 种基金the China Postdoctoral Science Foundation(Grant Nos.2019M661270)Key Laboratory of Micro-systems and Microstructures Manufacturing(Harbin Institute of Technology),Ministry of Education(Grant Nos.2019KM003).
文摘Diabetes is a chronic metabolic disease that has effect on blood sugar level and affects millions of people.We present an integrated flexible and reusable graphene-based field effect transistor(GFET)nanosensor for the detection of glucose using pyrene-1-boronic acid(PBA)as the receptor.The nanosensor fabricated on the polyimide performs GFET-based rapid transduction of the glucose-PBA binding,thereby potentially allowing the detection of glucose that are sampled reliably from human bodily fluids(e.g.,sweat)in wearable sensing applications.Due to the reversible binding interaction between PBA and glucose,reusability of our nanosensor can be realized by exposing graphene surface to acidic solution.In characterizing the stability and reusability of the nanosensor for wearable applications,we investigated the effects of substrate bending,multiple reuse and long-time storage on the equilibrium dissociation constant between the PBA and glucose.Results show that bending,multiple reuse(over 10 times)and long-time storage has negligible effect on the sensing performance.The detection of glucose with a limit of detection(LOD)of 0.15 μM and a dynamic range of 0.05-100 μM,which covers the reference scope of physical examination or screening of diabetes.Hence,our flexible GFET nanosensor is promising for wearable and reusable biosensing applications.
