Two-dimensional(2D)transition metal dichalcogenides(TMDCs)showed great potentials in 2D nanoelectronic devices due to their abundant and unique properties.The performance stability of the 2D TMDCs devices turns into o...Two-dimensional(2D)transition metal dichalcogenides(TMDCs)showed great potentials in 2D nanoelectronic devices due to their abundant and unique properties.The performance stability of the 2D TMDCs devices turns into one of the keys for their practical applications but has been rarely explored.Here,we investigated stability of MoS_(2)devices in ambient condition and contributed the device performance degradation to the surface oxidation of the contact metals with low work function,which increased the contact barrier and hindered the electron injection.We developed a new approach to recover the performance of the aged devices through the selective doping of contacts with organolithium,which prolonged the lifetime of MoS_(2)devices.Our work not only provides important insights into the stability of 2D TMDCs devices,but also opens up a new avenue for optimizing the performance of 2D MoS_(2)devices.展开更多
Edge effects are predicted to significantly impact the properties of low dimensional materials with layered structures. The synthesis of low dimensional materials with copious edges is desired for exploring the effect...Edge effects are predicted to significantly impact the properties of low dimensional materials with layered structures. The synthesis of low dimensional materials with copious edges is desired for exploring the effects of edges on the band structure and properties of these materials. Here we developed an approach for synthesizing MoS2 nanobelts terminated with vertically aligned edges by sulfurizing hydrothermally synthesized MoO3 nanobelts in the gas phase through a kinetically driven process; we then investigated the electrical and magnetic properties of these metastable materials. These edge-terminated MoS2 nanobelts were found to be metallic and ferromagnetic, and thus dramatically different from the semiconducting and nonmagnetic two-dimensional (2D) and three-dimensional (3D) 2H-MoS2 materials. The transitions in electrical and magnetic properties elucidate the fact that edges can tune the properties of low dimensional materials. The unique structure and properties of this one-dimensional (1D) MoS2 material will enable its applications in electronics, spintronics, and catalysis.展开更多
Chirality-specific growth of single-walled carbon nanotubes(SWNTs) remains a challenge for their practical applications in electronics. Here, we explored the surface growth of SWNTs by utilizing the atomic-precise sil...Chirality-specific growth of single-walled carbon nanotubes(SWNTs) remains a challenge for their practical applications in electronics. Here, we explored the surface growth of SWNTs by utilizing the atomic-precise silver cluster complex [Ag_(15){1,3,5–(C:C)_3–C_6H_3}_2(Py[8])_3–(CF_3SO_3)_3](CF_3SO_3)_6(Py[8] is abbreviation for octamethylazacalix[8]pyridine) as a catalyst precursor. The diameters of most acquired SWNTs distributed in the range of 1.2–1.4 nm, which is suitable for making high performance field-effect transistors. The high quality of the obtained SWNTs was evidenced by Raman spectroscopy and electrical measurements. Successful growth of high quality SWNTs in this study foresees that rational design of metal-organic complexes as growth catalysts can open up a new avenue for the controllable synthesis of SWNTs.展开更多
Two-dimensional (2D) anisotropic rhenium diselenide (ReSe2) has attracted lots ofattention due to its promising applications in electronics and optoelectronics. However,controlled synthesis of high quality ultrathin R...Two-dimensional (2D) anisotropic rhenium diselenide (ReSe2) has attracted lots ofattention due to its promising applications in electronics and optoelectronics. However,controlled synthesis of high quality ultrathin ReSe2 remains as a challenge.Here we developed an approach for synthesizing high quality 2D ReSe2 flakes witha thickness down to monolayer by chemical vapor transport (CVT) through carefullytuning the growth kinetics. The atomic structures and anisotropy of theobtained ReSe2 flakes were intensively characterized with scanning transmissionelectron microscope and angle-resolved polarized Raman spectroscopy. Fieldeffecttransistors fabricated on the CVT-grown ReSe2 flakes showed n-typesemiconducting behavior with an on/off current ratio of 105 and a mobility up to5 cm2 V−1 s−1, which is comparable to mechanically exfoliated flakes and isobvious higher than the samples synthesized with other approaches. This study notonly make high quality 2D ReSe2 easily accessible for both fundamental and applicationexplorations but also sheds new lights on the chemical synthesis of otheranisotropic 2D materials.展开更多
基金L.J.acknowledges the National Natural Science Foundation of China(No.21925504)Tsinghua Toyota Joint Research Fund.Z.H.C.acknowledges the National Natural Science Foundation of China(Nos.61674045,61911540074)Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(Nos.21XNLG27,22XNH097).
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDCs)showed great potentials in 2D nanoelectronic devices due to their abundant and unique properties.The performance stability of the 2D TMDCs devices turns into one of the keys for their practical applications but has been rarely explored.Here,we investigated stability of MoS_(2)devices in ambient condition and contributed the device performance degradation to the surface oxidation of the contact metals with low work function,which increased the contact barrier and hindered the electron injection.We developed a new approach to recover the performance of the aged devices through the selective doping of contacts with organolithium,which prolonged the lifetime of MoS_(2)devices.Our work not only provides important insights into the stability of 2D TMDCs devices,but also opens up a new avenue for optimizing the performance of 2D MoS_(2)devices.
文摘Edge effects are predicted to significantly impact the properties of low dimensional materials with layered structures. The synthesis of low dimensional materials with copious edges is desired for exploring the effects of edges on the band structure and properties of these materials. Here we developed an approach for synthesizing MoS2 nanobelts terminated with vertically aligned edges by sulfurizing hydrothermally synthesized MoO3 nanobelts in the gas phase through a kinetically driven process; we then investigated the electrical and magnetic properties of these metastable materials. These edge-terminated MoS2 nanobelts were found to be metallic and ferromagnetic, and thus dramatically different from the semiconducting and nonmagnetic two-dimensional (2D) and three-dimensional (3D) 2H-MoS2 materials. The transitions in electrical and magnetic properties elucidate the fact that edges can tune the properties of low dimensional materials. The unique structure and properties of this one-dimensional (1D) MoS2 material will enable its applications in electronics, spintronics, and catalysis.
基金the National Natural Science Foundation of China (21322303, 51372134 and 21573125)the financial support from the National Natural Science Foundation of China (21132005, 21421064 and 21522206)+1 种基金the National Program for Thousand Young Talents of Chinathe National Basic Research Program of China (2013CB834501)
文摘Chirality-specific growth of single-walled carbon nanotubes(SWNTs) remains a challenge for their practical applications in electronics. Here, we explored the surface growth of SWNTs by utilizing the atomic-precise silver cluster complex [Ag_(15){1,3,5–(C:C)_3–C_6H_3}_2(Py[8])_3–(CF_3SO_3)_3](CF_3SO_3)_6(Py[8] is abbreviation for octamethylazacalix[8]pyridine) as a catalyst precursor. The diameters of most acquired SWNTs distributed in the range of 1.2–1.4 nm, which is suitable for making high performance field-effect transistors. The high quality of the obtained SWNTs was evidenced by Raman spectroscopy and electrical measurements. Successful growth of high quality SWNTs in this study foresees that rational design of metal-organic complexes as growth catalysts can open up a new avenue for the controllable synthesis of SWNTs.
基金We acknowledge National Natural Science Foundation of China(Nos.21573125 and 21875127)Tsinghua University Initiative Scientific Research Program.
文摘Two-dimensional (2D) anisotropic rhenium diselenide (ReSe2) has attracted lots ofattention due to its promising applications in electronics and optoelectronics. However,controlled synthesis of high quality ultrathin ReSe2 remains as a challenge.Here we developed an approach for synthesizing high quality 2D ReSe2 flakes witha thickness down to monolayer by chemical vapor transport (CVT) through carefullytuning the growth kinetics. The atomic structures and anisotropy of theobtained ReSe2 flakes were intensively characterized with scanning transmissionelectron microscope and angle-resolved polarized Raman spectroscopy. Fieldeffecttransistors fabricated on the CVT-grown ReSe2 flakes showed n-typesemiconducting behavior with an on/off current ratio of 105 and a mobility up to5 cm2 V−1 s−1, which is comparable to mechanically exfoliated flakes and isobvious higher than the samples synthesized with other approaches. This study notonly make high quality 2D ReSe2 easily accessible for both fundamental and applicationexplorations but also sheds new lights on the chemical synthesis of otheranisotropic 2D materials.