The electronic and transport characteristics of protonated derivatives of naphthalocyanine(Nc)were investigated using density functional theory and non-equilibrium Green's functions.The results indicate that the p...The electronic and transport characteristics of protonated derivatives of naphthalocyanine(Nc)were investigated using density functional theory and non-equilibrium Green's functions.The results indicate that the protonation of external meso-N atoms of Nc preserves its planar structure and is energetically more favorable than the protonation of internal isoindole-N atoms.The protonation shifts the energy levels of system's frontier molecular orbitals closer to the Fermi level,thus creating channels for electron transport.In contrast with the semiconductor transport properties of H2Nc,its protonation products respond more sensitively to bias and exhibit negative differential resistance phenomena at specific bias.展开更多
Owing to rapid developments in spintronics,spin-based logic devices have emerged as promising tools for next-generation computing technologies.This paper provides a comprehensive review of recent advancements in spin ...Owing to rapid developments in spintronics,spin-based logic devices have emerged as promising tools for next-generation computing technologies.This paper provides a comprehensive review of recent advancements in spin logic devices,particularly focusing on fundamental device concepts rooted in nanomagnets,magnetoresistive random access memory,spin–orbit torques,electric-field modu-lation,and magnetic domain walls.The operation principles of these devices are comprehensively analyzed,and recent progress in spin logic devices based on negative differential resistance-enhanced anomalous Hall effect is summarized.These devices exhibit reconfigur-able logic capabilities and integrate nonvolatile data storage and computing functionalities.For current-driven spin logic devices,negative differential resistance elements are employed to nonlinearly enhance anomalous Hall effect signals from magnetic bits,enabling reconfig-urable Boolean logic operations.Besides,voltage-driven spin logic devices employ another type of negative differential resistance ele-ment to achieve logic functionalities with excellent cascading ability.By cascading several elementary logic gates,the logic circuit of a full adder can be obtained,and the potential of voltage-driven spin logic devices for implementing complex logic functions can be veri-fied.This review contributes to the understanding of the evolving landscape of spin logic devices and underscores the promising pro-spects they offer for the future of emerging computing schemes.展开更多
Developing emerging technologies in Internet of Things and artificial intelligence requires high-speed, low-power, high-sensitivity, and switchable-functionality strain sensors capable of sensing subtle mechanical sti...Developing emerging technologies in Internet of Things and artificial intelligence requires high-speed, low-power, high-sensitivity, and switchable-functionality strain sensors capable of sensing subtle mechanical stimuli in complex ambience. Resonant tunneling diodes (RTDs) are the good candidate for such sensing applications due to the ultrafast transport process, lower tunneling current, and negative differential resistance. However, notably enhancing sensing sensitivity remains one of the greatest challenges for RTD-related strain sensors. Here, we use piezotronic effect to improve sensing performance of strain sensors in double-barrier ZnO nanowire RTDs. This strain sensor not only possesses an ultrahigh gauge factor (GF) 390 GPa^(−1), two orders of magnitude higher than these reported RTD-based strain sensors, but also can switch the sensitivity with a GF ratio of 160 by adjusting bias voltage in a small range of 0.2 V. By employing Landauer–Büttiker quantum transport theory, we uncover two primary factors governing piezotronic modulation of resonant tunneling transport, i.e., the strain-mediated polarization field for manipulation of quantized subband levels, and the interfacial polarization charges for adjustment of space charge region. These two mechanisms enable strain to induce the negative differential resistance, amplify the peak-valley current ratio, and diminish the resonant bias voltage. These performances can be engineered by the regulation of bias voltage, temperature, and device architectures. Moreover, a strain sensor capable of electrically switching sensing performance within sensitive and insensitive regimes is proposed. This study not only offers a deep insight into piezotronic modulation of resonant tunneling physics, but also advances the RTD towards highly sensitive and multifunctional sensor applications.展开更多
Nanofluidic devices have turned out to be exemplary systems for investigating fluidic transport properties in a highly restricted area, where the electrostatic interactions or chemical reactions between nanochannel an...Nanofluidic devices have turned out to be exemplary systems for investigating fluidic transport properties in a highly restricted area, where the electrostatic interactions or chemical reactions between nanochannel and flowing species strongly dominate the ions and flow transport. Numerous nanofluidic devices have recently been explored to manipulate ion currents and construct electronic devices. Enlightened by electronic field effect transistors, utilizing the electric field effect of nanopore nanochannels has also been adopted to develop versatile nanofluidic devices. Here, we report a nanopore-based nanofluidic unijunction transistor composed of a conical glass nanopipette with the biomaterial polydopamine (PDA) coated at its outer surface. The asfabricated nanofluidic device exhibited negative differential resistance (NDR) and ion current oscillation (ICO) in ionic transport. The pre-doped copper ions in the PDA moved toward the tip as increasing the potential, having a robust shielding effect on the charge of the tip, thus affecting the surface charge density of the nanopore in the working zone. Finite element simulation based on a continuum model coupled with Stokes-Brinkman and Poisson-Nernst-Planck (PNP) equations revealed that the fluctuations in charge density remarkably affect the transport of ionic current in the nanofluidic device. The as-prepared nanofluidic semiconductor device was a ready-to-use equipment that required no additional external conditions. Our work provides a versatile and convenient way to construct nanofluidic electronic components;we believe by taking advantage of advanced surface modification methods, the oscillation frequency of the unijunction transistors could be controlled on demand, and more nanofluidic devices with resourceful functions would be exploited.展开更多
Tunneling-based static random-access memory(SRAM)devices have been developed to fulfill the demands of high density and low power,and the performance of SRAMs has also been greatly promoted.However,for a long time,the...Tunneling-based static random-access memory(SRAM)devices have been developed to fulfill the demands of high density and low power,and the performance of SRAMs has also been greatly promoted.However,for a long time,there has not been a silicon based tunneling device with both high peak valley current ratio(PVCR)and practicality,which remains a gap to be filled.Based on the existing work,the current manuscript proposed the concept of a new silicon-based tunneling device,i.e.,the silicon crosscoupled gated tunneling diode(Si XTD),which is quite simple in structure and almost completely compatible with mainstream technology.With technology computer aided design(TCAD)simulations,it has been validated that this type of device not only exhibits significant negative-differential-resistance(NDR)behavior with PVCRs up to 10^(6),but also possesses reasonable process margins.Moreover,SPICE simulation showed the great potential of such devices to achieve ultralow-power tunneling-based SRAMs with standby power down to 10^(−12)W.展开更多
A two-probe system was established for a finite (7, 0) silicon carbide (SiC) nanotube coupled to Au (111) surfaces via Au-C bonds. Using the non-equilibrium Green function (NEGF) combined with density functional theor...A two-probe system was established for a finite (7, 0) silicon carbide (SiC) nanotube coupled to Au (111) surfaces via Au-C bonds. Using the non-equilibrium Green function (NEGF) combined with density functional theory (DFT), the above system was studied for its electronic transport properties. Negative differential resistance (NDR) was observed when the bias voltage was greater than 1.4 V. Because the transport properties of the system were sensitive to the applied bias voltage, NDR might be caused by the fluctuation of the transmission coefficient with the bias voltage.展开更多
Using first-principles calculations based on density functional theory and the nonequilibrium Green＇s function formalism, we studied the spin transport through metal-phthalocyanine （MPc, M=Ni, Fe, Co, Mn, Cr） molec...Using first-principles calculations based on density functional theory and the nonequilibrium Green＇s function formalism, we studied the spin transport through metal-phthalocyanine （MPc, M=Ni, Fe, Co, Mn, Cr） molecules connected to aurum nanowire electrodes. We found that the MnPc, FePc, and CrPc molecular devices exhibit a perfect spin filtering effect compared to CoPc and NiPc. Moreover, negative differential resistance appears in FePc molecular devices. The transmission coefficients at different bias voltages were further presented to understand this phenomenon. These results would be useful in designing devices for future nanotechnology.展开更多
Based on non-equilibrium Green’s function method combined with the density functional theory, we have studied the electronic properties of a graphene nanoribbon (GNR) which is composed of two GNRs with different widt...Based on non-equilibrium Green’s function method combined with the density functional theory, we have studied the electronic properties of a graphene nanoribbon (GNR) which is composed of two GNRs with different widths. The results show that the electron transmission is greatly modulated by the applied bias. The current of the system displays negative differential resistance effect, which is attributed to the broadening of the transmission gap with the increase of the bias around the Fermi level.展开更多
By using first-principles calculations and nonequilibrium Green＇s function technique, we study elastic transport properties of crossed graphene nanoribbons. The results show that the electronic transport properties o...By using first-principles calculations and nonequilibrium Green＇s function technique, we study elastic transport properties of crossed graphene nanoribbons. The results show that the electronic transport properties of molecular junctions can be modulated by doped atoms. Negative differential resistance （NDR） behaviour can be observed in a certain bias region, when crossed graphene nanoribbons are doped with nitrogen atoms at the shoulder, but it cannot be observed for pristine crossed graphene nanoribbons at low biases. A mechanism for the negative differential resistance behaviour is suggested.展开更多
We demonstrate a high performance GaAs/AlGaAs-based quantum-well photodetector(QWP)device with a peak response frequency of 4.3 THz.The negative differential resistance(NDR)phenomenon is found in the dark currentvolta...We demonstrate a high performance GaAs/AlGaAs-based quantum-well photodetector(QWP)device with a peak response frequency of 4.3 THz.The negative differential resistance(NDR)phenomenon is found in the dark currentvoltage(I-V)curve in the current sweeping measurement mode,from which the breakdown voltage is determined.The photocurrent spectra and blackbody current responsivities at different voltages are measured.Based on the experimental data,the peak responsivity of 0.3 A/W(at 0.15 V,8 K)is derived,and the detection sensitivity is higher than 10^(11)Jones,which is in the similar level as that of the commercialized liquid-helium-cooled silicon bolometers.We attribute the high detection performance of the device to the small ohmic contact resistance of-2Ωand the big breakdown bias.展开更多
基金supported by the Postgraduate Inovation Programme of Changchun Wormal University(YJSCX202424)the Science and Technology Project of Jilin Provincial Education Department(JJKH20220828KJ)the Natural Science Foundation of Changchun Normal University(2020-005).
文摘The electronic and transport characteristics of protonated derivatives of naphthalocyanine(Nc)were investigated using density functional theory and non-equilibrium Green's functions.The results indicate that the protonation of external meso-N atoms of Nc preserves its planar structure and is energetically more favorable than the protonation of internal isoindole-N atoms.The protonation shifts the energy levels of system's frontier molecular orbitals closer to the Fermi level,thus creating channels for electron transport.In contrast with the semiconductor transport properties of H2Nc,its protonation products respond more sensitively to bias and exhibit negative differential resistance phenomena at specific bias.
基金sponsored by the National Key Research and Development Program of China(Nos.2017YFA0206202 and 2022YFA1203904)the National Natural Science Foundation of China(No.52271160).
文摘Owing to rapid developments in spintronics,spin-based logic devices have emerged as promising tools for next-generation computing technologies.This paper provides a comprehensive review of recent advancements in spin logic devices,particularly focusing on fundamental device concepts rooted in nanomagnets,magnetoresistive random access memory,spin–orbit torques,electric-field modu-lation,and magnetic domain walls.The operation principles of these devices are comprehensively analyzed,and recent progress in spin logic devices based on negative differential resistance-enhanced anomalous Hall effect is summarized.These devices exhibit reconfigur-able logic capabilities and integrate nonvolatile data storage and computing functionalities.For current-driven spin logic devices,negative differential resistance elements are employed to nonlinearly enhance anomalous Hall effect signals from magnetic bits,enabling reconfig-urable Boolean logic operations.Besides,voltage-driven spin logic devices employ another type of negative differential resistance ele-ment to achieve logic functionalities with excellent cascading ability.By cascading several elementary logic gates,the logic circuit of a full adder can be obtained,and the potential of voltage-driven spin logic devices for implementing complex logic functions can be veri-fied.This review contributes to the understanding of the evolving landscape of spin logic devices and underscores the promising pro-spects they offer for the future of emerging computing schemes.
基金supported from the National Natural Science Foundation of China(No.62404125)the Hubei Provincial Natural Science Foundation of China(No.2024AFB359)+5 种基金the Yichang City Natural Science Foundation of China(No.A24-3-004)the China Three Gorges University(No.2023RCKJ0035)the Basic Research Programs of Taicang,2021(No.TC2021JC20)the China Postdoctoral Science Foundation(No.2022M722588)the Young Talent Fund of Xi’an Association for Science and Technology(No.959202313090)the Key Research and Development Projects of Shaanxi Province(No.2024GX-YBXM-029).
文摘Developing emerging technologies in Internet of Things and artificial intelligence requires high-speed, low-power, high-sensitivity, and switchable-functionality strain sensors capable of sensing subtle mechanical stimuli in complex ambience. Resonant tunneling diodes (RTDs) are the good candidate for such sensing applications due to the ultrafast transport process, lower tunneling current, and negative differential resistance. However, notably enhancing sensing sensitivity remains one of the greatest challenges for RTD-related strain sensors. Here, we use piezotronic effect to improve sensing performance of strain sensors in double-barrier ZnO nanowire RTDs. This strain sensor not only possesses an ultrahigh gauge factor (GF) 390 GPa^(−1), two orders of magnitude higher than these reported RTD-based strain sensors, but also can switch the sensitivity with a GF ratio of 160 by adjusting bias voltage in a small range of 0.2 V. By employing Landauer–Büttiker quantum transport theory, we uncover two primary factors governing piezotronic modulation of resonant tunneling transport, i.e., the strain-mediated polarization field for manipulation of quantized subband levels, and the interfacial polarization charges for adjustment of space charge region. These two mechanisms enable strain to induce the negative differential resistance, amplify the peak-valley current ratio, and diminish the resonant bias voltage. These performances can be engineered by the regulation of bias voltage, temperature, and device architectures. Moreover, a strain sensor capable of electrically switching sensing performance within sensitive and insensitive regimes is proposed. This study not only offers a deep insight into piezotronic modulation of resonant tunneling physics, but also advances the RTD towards highly sensitive and multifunctional sensor applications.
基金supported by the National Natural Science Foundation of China(Nos.22374145 and 21675146)the Jilin Province Science Technology Development Plan Project(No.20230508075RC)the Youth Innovation Promotion Association CAS(No.2021224).
文摘Nanofluidic devices have turned out to be exemplary systems for investigating fluidic transport properties in a highly restricted area, where the electrostatic interactions or chemical reactions between nanochannel and flowing species strongly dominate the ions and flow transport. Numerous nanofluidic devices have recently been explored to manipulate ion currents and construct electronic devices. Enlightened by electronic field effect transistors, utilizing the electric field effect of nanopore nanochannels has also been adopted to develop versatile nanofluidic devices. Here, we report a nanopore-based nanofluidic unijunction transistor composed of a conical glass nanopipette with the biomaterial polydopamine (PDA) coated at its outer surface. The asfabricated nanofluidic device exhibited negative differential resistance (NDR) and ion current oscillation (ICO) in ionic transport. The pre-doped copper ions in the PDA moved toward the tip as increasing the potential, having a robust shielding effect on the charge of the tip, thus affecting the surface charge density of the nanopore in the working zone. Finite element simulation based on a continuum model coupled with Stokes-Brinkman and Poisson-Nernst-Planck (PNP) equations revealed that the fluctuations in charge density remarkably affect the transport of ionic current in the nanofluidic device. The as-prepared nanofluidic semiconductor device was a ready-to-use equipment that required no additional external conditions. Our work provides a versatile and convenient way to construct nanofluidic electronic components;we believe by taking advantage of advanced surface modification methods, the oscillation frequency of the unijunction transistors could be controlled on demand, and more nanofluidic devices with resourceful functions would be exploited.
基金supported by the National Key Research and Development Program of China under Grant No.2021YFB2800304.
文摘Tunneling-based static random-access memory(SRAM)devices have been developed to fulfill the demands of high density and low power,and the performance of SRAMs has also been greatly promoted.However,for a long time,there has not been a silicon based tunneling device with both high peak valley current ratio(PVCR)and practicality,which remains a gap to be filled.Based on the existing work,the current manuscript proposed the concept of a new silicon-based tunneling device,i.e.,the silicon crosscoupled gated tunneling diode(Si XTD),which is quite simple in structure and almost completely compatible with mainstream technology.With technology computer aided design(TCAD)simulations,it has been validated that this type of device not only exhibits significant negative-differential-resistance(NDR)behavior with PVCRs up to 10^(6),but also possesses reasonable process margins.Moreover,SPICE simulation showed the great potential of such devices to achieve ultralow-power tunneling-based SRAMs with standby power down to 10^(−12)W.
基金the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No. 60725415)
文摘A two-probe system was established for a finite (7, 0) silicon carbide (SiC) nanotube coupled to Au (111) surfaces via Au-C bonds. Using the non-equilibrium Green function (NEGF) combined with density functional theory (DFT), the above system was studied for its electronic transport properties. Negative differential resistance (NDR) was observed when the bias voltage was greater than 1.4 V. Because the transport properties of the system were sensitive to the applied bias voltage, NDR might be caused by the fluctuation of the transmission coefficient with the bias voltage.
基金This work was financially supported by the opening project of Key Laboratory for Photonic and Electronic Bandgap Materials of Ministry of Education and the National Nat- ural Science Foundation of China （Grant No. 11504072）.
文摘Using first-principles calculations based on density functional theory and the nonequilibrium Green＇s function formalism, we studied the spin transport through metal-phthalocyanine （MPc, M=Ni, Fe, Co, Mn, Cr） molecules connected to aurum nanowire electrodes. We found that the MnPc, FePc, and CrPc molecular devices exhibit a perfect spin filtering effect compared to CoPc and NiPc. Moreover, negative differential resistance appears in FePc molecular devices. The transmission coefficients at different bias voltages were further presented to understand this phenomenon. These results would be useful in designing devices for future nanotechnology.
文摘Based on non-equilibrium Green’s function method combined with the density functional theory, we have studied the electronic properties of a graphene nanoribbon (GNR) which is composed of two GNRs with different widths. The results show that the electron transmission is greatly modulated by the applied bias. The current of the system displays negative differential resistance effect, which is attributed to the broadening of the transmission gap with the increase of the bias around the Fermi level.
基金supported by the National Natural Science Foundation of China (Grant Nos.10325415 and 50504017)the Natural Science Foundation of Hunan Province,China (Grant No.07JJ3102)the Science Develop Foundation of Central South University,China (Grant Nos.08SDF02 and 09SDF09)
文摘By using first-principles calculations and nonequilibrium Green＇s function technique, we study elastic transport properties of crossed graphene nanoribbons. The results show that the electronic transport properties of molecular junctions can be modulated by doped atoms. Negative differential resistance （NDR） behaviour can be observed in a certain bias region, when crossed graphene nanoribbons are doped with nitrogen atoms at the shoulder, but it cannot be observed for pristine crossed graphene nanoribbons at low biases. A mechanism for the negative differential resistance behaviour is suggested.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFF0106302)the National Basic Research Program of of China(Grant No.2014CB339803)+1 种基金the National Natural Science Foundation of China(Grant Nos.61404150,61405233,and 61604161)the Shanghai Municipal Commission of Science and Technology,China(Grant Nos.15JC1403800,17ZR1448300,and 17YF1429900)
文摘We demonstrate a high performance GaAs/AlGaAs-based quantum-well photodetector(QWP)device with a peak response frequency of 4.3 THz.The negative differential resistance(NDR)phenomenon is found in the dark currentvoltage(I-V)curve in the current sweeping measurement mode,from which the breakdown voltage is determined.The photocurrent spectra and blackbody current responsivities at different voltages are measured.Based on the experimental data,the peak responsivity of 0.3 A/W(at 0.15 V,8 K)is derived,and the detection sensitivity is higher than 10^(11)Jones,which is in the similar level as that of the commercialized liquid-helium-cooled silicon bolometers.We attribute the high detection performance of the device to the small ohmic contact resistance of-2Ωand the big breakdown bias.
