NH3-plasma treatment is used to improve the quality of the gate dielectric and interface. Al2O3 is adopted as a buffer layer between HfO2 and MoS2 to decrease the interface-state density. Four groups of MOS capacitors...NH3-plasma treatment is used to improve the quality of the gate dielectric and interface. Al2O3 is adopted as a buffer layer between HfO2 and MoS2 to decrease the interface-state density. Four groups of MOS capacitors and back-gate transistors with different gate dielectrics are fabricated and their C–V and I–V characteristics are compared. It is found that the Al2O3/HfO2 back-gate transistor with NH3-plasma treatment shows the best electrical performance: high on–off current ratio of 1.53 × 107, higher field-effect mobility of 26.51 cm2/V·s, and lower subthreshold swing of 145 m V/dec.These are attributed to the improvements of the gate dielectric and interface qualities by the NH3-plasma treatment and the addition of Al2O3 as a buffer layer.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
Because of the coupling between semiconducting and piezoelectric properties in wurtzite materials, strain-induced piezo-charges can tune the charge transport across the interface or junction, which is referred to as t...Because of the coupling between semiconducting and piezoelectric properties in wurtzite materials, strain-induced piezo-charges can tune the charge transport across the interface or junction, which is referred to as the piezotronic effect. For devices whose dimension is much smaller than the mean free path of carriers （such as a single atomic layer of MoS2）, ballistic transport occurs. In this study, transport in the monolayer MoS2 piezotronic transistor is studied by presenting analytical solutions for two-dimensional （2D） MoS2. Furthermore, a numerical simulation for guiding future 2D piezotronic nanodevice design is presented.展开更多
二维半导体过渡金属二硫属化物(transition metal dichalcogenide,TMD)具有独特的电学、光学和力学性能,在数字电路、光伏器件和能量存储等多个领域中具有巨大的应用潜力。通过表面掺杂控制TMD的电学性能为实现灵敏传感提供了有效的方...二维半导体过渡金属二硫属化物(transition metal dichalcogenide,TMD)具有独特的电学、光学和力学性能,在数字电路、光伏器件和能量存储等多个领域中具有巨大的应用潜力。通过表面掺杂控制TMD的电学性能为实现灵敏传感提供了有效的方法。本文开展了氧等离子体对二硫化钼(MoS_(2))掺杂特性的研究。首先,测试了MoS_(2)场效应晶体管(field-effect transistor,FET)的输运特性,发现氧等离子体处理对FET具有p型掺杂作用。随后,通过拉曼光谱研究了掺杂机制的成因,并证实了沟道表面类MoO_(3)缺陷的形成。最后,研究了经等离子体处理的晶体管的湿度传感特性,由于氧等离子体处理使得沟道对水分子的吸收中心增加,在潮湿环境下晶体管具有十分灵敏的响应特性,源漏电流值变化了约54%。这项工作不仅提供了一种调控TMD电学性能的简单方法,也展示了低维材料化学传感器的发展潜力。展开更多
With the support by the National Natural Science Foundation of China,a collaborative study by the research group led by Prof.Zhang Zhidong(张志东)and Prof.Han Zheng(韩拯)from the Institute of Metal Research,Chinese Ac...With the support by the National Natural Science Foundation of China,a collaborative study by the research group led by Prof.Zhang Zhidong(张志东)and Prof.Han Zheng(韩拯)from the Institute of Metal Research,Chinese Academy of Sciences demonstrates that by intercalating a tunneling layer展开更多
Recently,two-dimensional materials have been attracting increasing attention because of their novel properties and promising applications.However,the impurity doping remains a significant challenge owing to the lack o...Recently,two-dimensional materials have been attracting increasing attention because of their novel properties and promising applications.However,the impurity doping remains a significant challenge owing to the lack of the doping strategy in the atomically thin layers.Here we report on the chromium（Cr） and manganese（Mn）doping in atomically-thin MoS_2 crystals grown by chemical vapor deposition.The Cr/Mn doped MoS_2 samples are characterized by a peak at 1.76 and 1.79 eV in photoluminescence spectra,respectively,compared with the undoped one at 1.85 eV.The field-effect transistor（FET） devices based on the Mn doping show a higher threshold voltage than that of the pure MoS_2 while the Cr doping exhibits the opposite behavior.Importantly,the carrier concentration in these samples displays a remarkable difference arising from the doping effect,consistent with the evolution of the FET performance.The temperature-dependent conductivity measurements further demonstrate a large variation in activation energy.The successful incorporation of the Mn and Cr impurities into the monolayer MoS_2 paves the way towards the high Curie temperature two-dimensional dilute magnetic semiconductors.展开更多
Atomically thin two-dimensional semiconductor nanomaterials have attained considerable attention currently. Here, we present a nano-optomechanical system based on a suspended monolayer molybdenum disulfide （MoS2）. T...Atomically thin two-dimensional semiconductor nanomaterials have attained considerable attention currently. Here, we present a nano-optomechanical system based on a suspended monolayer molybdenum disulfide （MoS2）. The linear and nonlinear coherent optical properties of this system, and the phenomenon ofphonon-induced transparency are demonstrated. The transmission of the probe field can be manipulated by the power of a second ‘gating＇ （pump） field, which indicates a promising candidate for an optical transistor. We further study the nonlinear effect of the system, and the optical Kerr effect of the monolayer MoS2 resonator can be regulated under different parameter regimes. This scheme proposed here may indicate potential chip-scale applications of monolayer MoS2 resonator in quantum information with the currently popular pump-probe technology.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61774064)
文摘NH3-plasma treatment is used to improve the quality of the gate dielectric and interface. Al2O3 is adopted as a buffer layer between HfO2 and MoS2 to decrease the interface-state density. Four groups of MOS capacitors and back-gate transistors with different gate dielectrics are fabricated and their C–V and I–V characteristics are compared. It is found that the Al2O3/HfO2 back-gate transistor with NH3-plasma treatment shows the best electrical performance: high on–off current ratio of 1.53 × 107, higher field-effect mobility of 26.51 cm2/V·s, and lower subthreshold swing of 145 m V/dec.These are attributed to the improvements of the gate dielectric and interface qualities by the NH3-plasma treatment and the addition of Al2O3 as a buffer layer.
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.
基金This work was supported by the ＂thousands talents＂ program for pioneer researcher and his innovation team, China, the National Natural Science Foundation of China （No. 51432005）, and Beijing Municipal Commission of Science and Technology （Nos. Z131100006013005 and Z131100006013004）.
文摘Because of the coupling between semiconducting and piezoelectric properties in wurtzite materials, strain-induced piezo-charges can tune the charge transport across the interface or junction, which is referred to as the piezotronic effect. For devices whose dimension is much smaller than the mean free path of carriers （such as a single atomic layer of MoS2）, ballistic transport occurs. In this study, transport in the monolayer MoS2 piezotronic transistor is studied by presenting analytical solutions for two-dimensional （2D） MoS2. Furthermore, a numerical simulation for guiding future 2D piezotronic nanodevice design is presented.
基金National Natural Science Foundation of China(No.62005042)。
文摘二维半导体过渡金属二硫属化物(transition metal dichalcogenide,TMD)具有独特的电学、光学和力学性能,在数字电路、光伏器件和能量存储等多个领域中具有巨大的应用潜力。通过表面掺杂控制TMD的电学性能为实现灵敏传感提供了有效的方法。本文开展了氧等离子体对二硫化钼(MoS_(2))掺杂特性的研究。首先,测试了MoS_(2)场效应晶体管(field-effect transistor,FET)的输运特性,发现氧等离子体处理对FET具有p型掺杂作用。随后,通过拉曼光谱研究了掺杂机制的成因,并证实了沟道表面类MoO_(3)缺陷的形成。最后,研究了经等离子体处理的晶体管的湿度传感特性,由于氧等离子体处理使得沟道对水分子的吸收中心增加,在潮湿环境下晶体管具有十分灵敏的响应特性,源漏电流值变化了约54%。这项工作不仅提供了一种调控TMD电学性能的简单方法,也展示了低维材料化学传感器的发展潜力。
文摘With the support by the National Natural Science Foundation of China,a collaborative study by the research group led by Prof.Zhang Zhidong(张志东)and Prof.Han Zheng(韩拯)from the Institute of Metal Research,Chinese Academy of Sciences demonstrates that by intercalating a tunneling layer
基金Project supported by the National Young 1000 Talent Planthe Pujiang Talent Plan in Shanghai+1 种基金the National Natural Science Foundation of China(Nos.61322407,11474058,61674040)the Chinese National Science Fund for Talent Training in Basic Science(No.J1103204)
文摘Recently,two-dimensional materials have been attracting increasing attention because of their novel properties and promising applications.However,the impurity doping remains a significant challenge owing to the lack of the doping strategy in the atomically thin layers.Here we report on the chromium（Cr） and manganese（Mn）doping in atomically-thin MoS_2 crystals grown by chemical vapor deposition.The Cr/Mn doped MoS_2 samples are characterized by a peak at 1.76 and 1.79 eV in photoluminescence spectra,respectively,compared with the undoped one at 1.85 eV.The field-effect transistor（FET） devices based on the Mn doping show a higher threshold voltage than that of the pure MoS_2 while the Cr doping exhibits the opposite behavior.Importantly,the carrier concentration in these samples displays a remarkable difference arising from the doping effect,consistent with the evolution of the FET performance.The temperature-dependent conductivity measurements further demonstrate a large variation in activation energy.The successful incorporation of the Mn and Cr impurities into the monolayer MoS_2 paves the way towards the high Curie temperature two-dimensional dilute magnetic semiconductors.
基金Project supported by the National Natural Science Foundation of China(Nos.11404005,51502005,61272153,61572035)the Key Foundation for Young Talents in College of Anhui Province(No.2013SQRL026ZD)the Foundation for PhD in Anhui University of Science and Technology
文摘Atomically thin two-dimensional semiconductor nanomaterials have attained considerable attention currently. Here, we present a nano-optomechanical system based on a suspended monolayer molybdenum disulfide （MoS2）. The linear and nonlinear coherent optical properties of this system, and the phenomenon ofphonon-induced transparency are demonstrated. The transmission of the probe field can be manipulated by the power of a second ‘gating＇ （pump） field, which indicates a promising candidate for an optical transistor. We further study the nonlinear effect of the system, and the optical Kerr effect of the monolayer MoS2 resonator can be regulated under different parameter regimes. This scheme proposed here may indicate potential chip-scale applications of monolayer MoS2 resonator in quantum information with the currently popular pump-probe technology.
