一、“智能摩尔”技术背景概述自1965年戈登·摩尔提出摩尔定律以来,传统摩尔技术路线开始不断演进,当前基于CMOS开关的半导体工艺技术遭遇到物理极限的制约,半导体产业已进入后摩尔时代。延续摩尔(More Moore)技术通过不断改进半...一、“智能摩尔”技术背景概述自1965年戈登·摩尔提出摩尔定律以来,传统摩尔技术路线开始不断演进,当前基于CMOS开关的半导体工艺技术遭遇到物理极限的制约,半导体产业已进入后摩尔时代。延续摩尔(More Moore)技术通过不断改进半导体工艺制程,以减小器件沟道宽度的方法来提高单片晶体管集成密度,正逐渐接近1nm的量子极限。拓展摩尔(More Than Moore)技术通过在单芯片中堆叠多个DIE来提升单个元器件的性能,但也受到功耗和散热的限制。展开更多
Overcoming the sub-5 nm gate length limit and decreasing the power dissipation are two main objects in the electronics research field. Besides advanced engineering techniques, considering new material systems may be h...Overcoming the sub-5 nm gate length limit and decreasing the power dissipation are two main objects in the electronics research field. Besides advanced engineering techniques, considering new material systems may be helpful. Here, we demonstrate two-dimensional(2D) subthermionic field-effect transistors(FETs) with sub-5 nm gate lengths based on ferroelectric(FE) van der Waals heterostructures(vdWHs).The FE vd WHs are composed of graphene, MoS2, and CuInP2S6 acting as 2D contacts, channels, and ferroelectric dielectric layers, respectively. We first show that the as-fabricated long-channel device exhibits nearly hysteresis-free subthermionic switching over three orders of magnitude of drain current at room temperature. Further, we fabricate short-channel subthermionic FETs using metallic carbon nanotubes as effective gate terminals. A typical device shows subthermionic switching over five-to-six orders of magnitude of drain current with a minimum subthreshold swing of 6.1 mV/dec at room temperature. Our results indicate that 2D materials system is promising for advanced highly-integrated energy-efficient electronic devices.展开更多
Existing multi-channel Medium Access Control (MAC) protocols have been demonstrated to significantly increase wireless network performance compared to single channel MAC protocols. Traditionally, the channelization st...Existing multi-channel Medium Access Control (MAC) protocols have been demonstrated to significantly increase wireless network performance compared to single channel MAC protocols. Traditionally, the channelization structure in IEEE 802.11 based wireless networks is pre-configured, and the entire available spectrum is divided into subchannels and equal channel widths. In contrast, this paper presents a Traffic-Aware Channelization MAC (TAC-MAC) protocol for wireless ad hoc networks, where each node is equipped with a single half duplex transceiver. TAC-MAC works in a distributed, fine-grai-ned manner, which dynamically divides variable-width subchannels and allocates subchannel width based on the Orthogonal Frequency Division Multiplexing (OFDM) technique according to the traffic demands of nodes. Simulations show that the TAC-MAC can significantly improve network throughput and reduce packet delay compared with both fixed-width multi-channel MAC and single channel 802.11 protocols, which illustrates a new paradigm for high-efficient multi-channel MAC design in wireless ad hoc networks.展开更多
The effect of channel length and width on the large and small-signal parameters of the graphene field effect transistor have been explored using an analytical approach.In the case of faster saturation as well as extre...The effect of channel length and width on the large and small-signal parameters of the graphene field effect transistor have been explored using an analytical approach.In the case of faster saturation as well as extremely high transit frequency,the graphene field effect transistor shows outstanding performance.From the transfer curve,it is observed that there is a positive shift of Dirac point from the voltage of 0.15 V to 0.35 V because of reducing channel length from 440 nm to 20 nm and this curve depicts that graphene shows ambipolar behavior.Besides,it is found that because of widening channel the drain current increases and the maximum current is found approximately 2.4 mA and 6 mA for channel width 2μm and 5μm respectively.Furthermore,an approximate symmetrical capacitance-voltage(C-V)characteristic of the graphene field effect transistor is obtained and the capacitance reduces when the channel length decreases but the capacitance can be increased by raising the channel width.In addition,a high transconductance,that demands high-speed radio frequency(RF)applications,of 6.4 mS at channel length 20 nm and 4.45 mS at channel width 5μm along with a high transit frequency of 3.95 THz have been found that demands high-speed radio frequency applications.展开更多
The extra sediment load induced by typhoons and rainstorms in the Heshe River, Taiwan, are the principal reason for severe sediment-related disasters. The total sediment load during Typhoon Morakot in 9009 was 31 x lo...The extra sediment load induced by typhoons and rainstorms in the Heshe River, Taiwan, are the principal reason for severe sediment-related disasters. The total sediment load during Typhoon Morakot in 9009 was 31 x lo6 m3, accounting for 95% of the annual sediment discharge. Large amounts of sediment load entered the Hoshe River, causing the braiding index （BI） to increase. Subsequently, the BI became positively correlated with the channel width in the Hoshe River. The specific typhoon and rainstorm events decreased after Typhoon Morakot, the sediment input decreased, inducing the fluvial morphology of the braided river to develop into a meandering river. The extra sediment load induced the deposition depth to increase and produce a headward deposition in the main channel and its tributaries. In addition, the river bend and the topographical notch restrained the sediment from moving downstream and being stored locally, indirectly increasing the erosion density of the river banks from 2.5 to lo.5 times.展开更多
文摘一、“智能摩尔”技术背景概述自1965年戈登·摩尔提出摩尔定律以来,传统摩尔技术路线开始不断演进,当前基于CMOS开关的半导体工艺技术遭遇到物理极限的制约,半导体产业已进入后摩尔时代。延续摩尔(More Moore)技术通过不断改进半导体工艺制程,以减小器件沟道宽度的方法来提高单片晶体管集成密度,正逐渐接近1nm的量子极限。拓展摩尔(More Than Moore)技术通过在单芯片中堆叠多个DIE来提升单个元器件的性能,但也受到功耗和散热的限制。
基金This work was supported by National Key R&D Program of China(2018YFA0703700 and 2016YFA0200700)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB30000000)+2 种基金the National Natural Science Foundation of China(61625401,61851403,11674072,91964203,and 61804146)CAS Key Laboratory of Nanosystem and Hierarchical FabricationThe authors also gratefully acknowledge the support of Youth Innovation Promotion Association CAS.
文摘Overcoming the sub-5 nm gate length limit and decreasing the power dissipation are two main objects in the electronics research field. Besides advanced engineering techniques, considering new material systems may be helpful. Here, we demonstrate two-dimensional(2D) subthermionic field-effect transistors(FETs) with sub-5 nm gate lengths based on ferroelectric(FE) van der Waals heterostructures(vdWHs).The FE vd WHs are composed of graphene, MoS2, and CuInP2S6 acting as 2D contacts, channels, and ferroelectric dielectric layers, respectively. We first show that the as-fabricated long-channel device exhibits nearly hysteresis-free subthermionic switching over three orders of magnitude of drain current at room temperature. Further, we fabricate short-channel subthermionic FETs using metallic carbon nanotubes as effective gate terminals. A typical device shows subthermionic switching over five-to-six orders of magnitude of drain current with a minimum subthreshold swing of 6.1 mV/dec at room temperature. Our results indicate that 2D materials system is promising for advanced highly-integrated energy-efficient electronic devices.
基金supported by the National Natural Science Foundation of China under Grant No. 61002032the Doctoral Fund of Ministry of Education of China under Grant No. 20094307110004
文摘Existing multi-channel Medium Access Control (MAC) protocols have been demonstrated to significantly increase wireless network performance compared to single channel MAC protocols. Traditionally, the channelization structure in IEEE 802.11 based wireless networks is pre-configured, and the entire available spectrum is divided into subchannels and equal channel widths. In contrast, this paper presents a Traffic-Aware Channelization MAC (TAC-MAC) protocol for wireless ad hoc networks, where each node is equipped with a single half duplex transceiver. TAC-MAC works in a distributed, fine-grai-ned manner, which dynamically divides variable-width subchannels and allocates subchannel width based on the Orthogonal Frequency Division Multiplexing (OFDM) technique according to the traffic demands of nodes. Simulations show that the TAC-MAC can significantly improve network throughput and reduce packet delay compared with both fixed-width multi-channel MAC and single channel 802.11 protocols, which illustrates a new paradigm for high-efficient multi-channel MAC design in wireless ad hoc networks.
基金supported by the National Key Research and Development Program of China(No.2018YFE0204000)the National Natural Science Foundation of China(No.61674141,No.51972300,No.61504134 and No.21975245)+2 种基金The Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB43000000)The World Academy of Sciences(TWAS),and the Key Research Program of Frontier Science,Chinese Academy of Sciences(No.QYZDBSSW-SLH006)support from Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2020114).
文摘The effect of channel length and width on the large and small-signal parameters of the graphene field effect transistor have been explored using an analytical approach.In the case of faster saturation as well as extremely high transit frequency,the graphene field effect transistor shows outstanding performance.From the transfer curve,it is observed that there is a positive shift of Dirac point from the voltage of 0.15 V to 0.35 V because of reducing channel length from 440 nm to 20 nm and this curve depicts that graphene shows ambipolar behavior.Besides,it is found that because of widening channel the drain current increases and the maximum current is found approximately 2.4 mA and 6 mA for channel width 2μm and 5μm respectively.Furthermore,an approximate symmetrical capacitance-voltage(C-V)characteristic of the graphene field effect transistor is obtained and the capacitance reduces when the channel length decreases but the capacitance can be increased by raising the channel width.In addition,a high transconductance,that demands high-speed radio frequency(RF)applications,of 6.4 mS at channel length 20 nm and 4.45 mS at channel width 5μm along with a high transit frequency of 3.95 THz have been found that demands high-speed radio frequency applications.
文摘The extra sediment load induced by typhoons and rainstorms in the Heshe River, Taiwan, are the principal reason for severe sediment-related disasters. The total sediment load during Typhoon Morakot in 9009 was 31 x lo6 m3, accounting for 95% of the annual sediment discharge. Large amounts of sediment load entered the Hoshe River, causing the braiding index （BI） to increase. Subsequently, the BI became positively correlated with the channel width in the Hoshe River. The specific typhoon and rainstorm events decreased after Typhoon Morakot, the sediment input decreased, inducing the fluvial morphology of the braided river to develop into a meandering river. The extra sediment load induced the deposition depth to increase and produce a headward deposition in the main channel and its tributaries. In addition, the river bend and the topographical notch restrained the sediment from moving downstream and being stored locally, indirectly increasing the erosion density of the river banks from 2.5 to lo.5 times.
