Graphene has demonstrated its potential in several practical applications owing to its remarkable electronic and physical properties. In this study, we successfully fabricated a suspended graphene device with a width ...Graphene has demonstrated its potential in several practical applications owing to its remarkable electronic and physical properties. In this study, we successfully fabricated a suspended graphene device with a width down to 20 nm. The morphological evolution of graphene under various electric field effects was systematically examined using an in-situ transmission electron microscope （TEM）. The hourglass-shaped graphene sample instantly broke apart at 7.5 mA, indicating an impressive breakdown current density. The current-carrying capacity was calculated to be -1.6 × 10^9 A.cm-2, which is several orders higher than that of copper. The current-carrying capacity depended on the resistivity of graphene. In addition, atomic volume changes occurred in the multilayer graphene samples due to surface diffusion and Ostwald ripening （OR）, indicating that the breakdown mechanism is well approximated by the electric field. This study not only provides a theory to explain the breakdown behavior but also presents the effects on materials contacted with a graphene layer used as the transmission path.展开更多
Highly repeatable multilevel bipolar resistive switching in Ti/Ce Ox/Pt nonvolatile memory device has been demonstrated. X-ray diffraction studies of Ce O2 films reveal the formation of weak polycrystalline structure....Highly repeatable multilevel bipolar resistive switching in Ti/Ce Ox/Pt nonvolatile memory device has been demonstrated. X-ray diffraction studies of Ce O2 films reveal the formation of weak polycrystalline structure. The observed good memory performance, including stable cycling endurance and long data retention times（〉10^4s） with an acceptable resistance ratio（～10^2）, enables the device for its applications in future non-volatile resistive random access memories（RRAMs）. Based on the unique distribution characteristics of oxygen vacancies in Ce Ox films, the possible mechanism of multilevel resistive switching in Ce Ox RRAM devices has been discussed. The conduction mechanism in low resistance state is found to be Ohmic due to conductive filamentary paths, while that in the high resistance state was identified as Ohmic for low applied voltages and a space-charge-limited conduction dominated by Schottky emission at high applied voltages.展开更多
Electric-induced resistive switching effects have attracted wide attention for future nonvolatile memory applications known as resistive random access memory(RRAM).RRAM is one of the promising candidates because of it...Electric-induced resistive switching effects have attracted wide attention for future nonvolatile memory applications known as resistive random access memory(RRAM).RRAM is one of the promising candidates because of its excellent properties including simple device structure,high operation speed,low power consumption and high density integration.The RRAM devices pri-marily utilize different resistance values to store the digital data and can keep the resistance state without any power.Recent advances in the understanding of the resistive switching mechanism are described by a thermal or electrochemical redox reaction near the interface between the oxide and the active metal electrode.This paper reviews the ongoing research and development activities on the interface engineering of the RRAM devices.The possible switching mechanisms for the bistable resistive switching are described.The effects of formation,composition and thickness of the interface layer on the resistive switching characteristics and consequently the memory performance are also discussed.展开更多
Two-dimensional semiconductors,such as MoS2 are known to be highly susceptible to diverse molecular adsorbates on the surface during fabrication,which could adversely affect device performance.To ensure high device yi...Two-dimensional semiconductors,such as MoS2 are known to be highly susceptible to diverse molecular adsorbates on the surface during fabrication,which could adversely affect device performance.To ensure high device yield,uniformity and performance,the semiconductor industry has long employed wet chemical cleaning strategies to remove undesirable surface contaminations,adsorbates,and native oxides from the surface of Si wafers.A similarly effective surface cleaning technique for two-dimensional materials has not yet been fully developed.In this study,we propose a wet chemical cleaning strategy for MoS2 by using N-methyl-2-pyrrolidone.The cleaning process not only preserves the intrinsic properties of monolayer MoS2,but also significantly improves the performance of monolayer MoS2 field-effect-transistors.Superior device on current of 12 μA·μm-1 for a channel length of 400 nm,contact resistance of 15 kΩ·μm,field-effect mobility of 15.5 cm^2·V^-1·s^-1,and the average on-off current ratio of 10^8 were successfully demonstrated.展开更多
文摘Graphene has demonstrated its potential in several practical applications owing to its remarkable electronic and physical properties. In this study, we successfully fabricated a suspended graphene device with a width down to 20 nm. The morphological evolution of graphene under various electric field effects was systematically examined using an in-situ transmission electron microscope （TEM）. The hourglass-shaped graphene sample instantly broke apart at 7.5 mA, indicating an impressive breakdown current density. The current-carrying capacity was calculated to be -1.6 × 10^9 A.cm-2, which is several orders higher than that of copper. The current-carrying capacity depended on the resistivity of graphene. In addition, atomic volume changes occurred in the multilayer graphene samples due to surface diffusion and Ostwald ripening （OR）, indicating that the breakdown mechanism is well approximated by the electric field. This study not only provides a theory to explain the breakdown behavior but also presents the effects on materials contacted with a graphene layer used as the transmission path.
基金the financial support by Higher Education Commission(HEC),Islamabad Pakistan
文摘Highly repeatable multilevel bipolar resistive switching in Ti/Ce Ox/Pt nonvolatile memory device has been demonstrated. X-ray diffraction studies of Ce O2 films reveal the formation of weak polycrystalline structure. The observed good memory performance, including stable cycling endurance and long data retention times（〉10^4s） with an acceptable resistance ratio（～10^2）, enables the device for its applications in future non-volatile resistive random access memories（RRAMs）. Based on the unique distribution characteristics of oxygen vacancies in Ce Ox films, the possible mechanism of multilevel resistive switching in Ce Ox RRAM devices has been discussed. The conduction mechanism in low resistance state is found to be Ohmic due to conductive filamentary paths, while that in the high resistance state was identified as Ohmic for low applied voltages and a space-charge-limited conduction dominated by Schottky emission at high applied voltages.
文摘Electric-induced resistive switching effects have attracted wide attention for future nonvolatile memory applications known as resistive random access memory(RRAM).RRAM is one of the promising candidates because of its excellent properties including simple device structure,high operation speed,low power consumption and high density integration.The RRAM devices pri-marily utilize different resistance values to store the digital data and can keep the resistance state without any power.Recent advances in the understanding of the resistive switching mechanism are described by a thermal or electrochemical redox reaction near the interface between the oxide and the active metal electrode.This paper reviews the ongoing research and development activities on the interface engineering of the RRAM devices.The possible switching mechanisms for the bistable resistive switching are described.The effects of formation,composition and thickness of the interface layer on the resistive switching characteristics and consequently the memory performance are also discussed.
文摘Two-dimensional semiconductors,such as MoS2 are known to be highly susceptible to diverse molecular adsorbates on the surface during fabrication,which could adversely affect device performance.To ensure high device yield,uniformity and performance,the semiconductor industry has long employed wet chemical cleaning strategies to remove undesirable surface contaminations,adsorbates,and native oxides from the surface of Si wafers.A similarly effective surface cleaning technique for two-dimensional materials has not yet been fully developed.In this study,we propose a wet chemical cleaning strategy for MoS2 by using N-methyl-2-pyrrolidone.The cleaning process not only preserves the intrinsic properties of monolayer MoS2,but also significantly improves the performance of monolayer MoS2 field-effect-transistors.Superior device on current of 12 μA·μm-1 for a channel length of 400 nm,contact resistance of 15 kΩ·μm,field-effect mobility of 15.5 cm^2·V^-1·s^-1,and the average on-off current ratio of 10^8 were successfully demonstrated.
