Interlayer interactions at the heterointerfaces of van der Waals heterostructures (vdWHs), which consist of vertically stacked two-dimensional materials, play important roles in determining their properties. The inter...Interlayer interactions at the heterointerfaces of van der Waals heterostructures (vdWHs), which consist of vertically stacked two-dimensional materials, play important roles in determining their properties. The interlayer interactions are tunable from noncoupling to strong coupling by controlling the twist angle between adjacent layers. However, the influence of stacking sequence and individual component thickness on the properties of vdWHs has rarely been explored. In this work, the influence of the stacking sequence of WSe2 and graphene in vdWHs of graphene-on-WSe2 (graphene/WSe2) or WSe2-on-graphene (WSe2/graphene), as well as their thickness, on their interlayer interaction was systematically investigated by ultralow-frequency (ULF) Raman spectroscopy. A series of ULF breathing modes of WSe2 nanosheets in these vdWHs were observed with frequencies highly dependent on graphene thickness. Interestingly, the ULF breathing modes of WSe2 red-shifted in graphene/WSe2 and WSe2/graphene configurations, and the amount of shift in the former was much larger than that in the latter. In contrast, no obvious ULF shift was observed by varying the twist angle between WSe2 and graphene. This indicates that the interlayer interaction is more sensitive to the stacking sequence compared with the twist angle. The results provide alternative approaches to modulate the interlayer interaction of vdWHs and, thus, tune their optical and optoelectronic properties.展开更多
Hexagonal boron nitride(h‐BN)is a semiconductor material with a wide band gap,holding promising potential for applications in thermal conductivity devices and nanoresonators in the field of microelectronics.Here,mole...Hexagonal boron nitride(h‐BN)is a semiconductor material with a wide band gap,holding promising potential for applications in thermal conductivity devices and nanoresonators in the field of microelectronics.Here,molecular dynamics is simulated to investigate the tensile and vibrational behaviors of bilayer h‐BN under five different stacking modes across varying temperatures.The mechanical properties of five different stacking modes of h‐BN at various temperatures are focused on,including Young's modulus,the ultimate stress,and the ultimate strain.Results indicate that bilayer h‐BN nanosheets exhibit anisotropic characteristics,with their tensile properties decreasing as temperature increases.Additionally,we explore the influence of temperature on the natural frequency of bilayer h‐BN under five different stacking modes.These results establish a fundamental understanding of the mechanical and vibrational characteristics of bilayer h‐BN nanosheets under different stacking modes,contributing to their potential applications in advanced nanodevices operating in extremely high‐temperature environments.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 21571101 and 51322202)the Natural Science Foundation of Jiangsu Province in China (Grant Nos. BK20161543 and BK20130927)+1 种基金the Joint Research Fund for Overseas Chinese, Hong Kong and Macao Scholars (Grant No. 51528201)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Grant No. 15KJB430016).
文摘Interlayer interactions at the heterointerfaces of van der Waals heterostructures (vdWHs), which consist of vertically stacked two-dimensional materials, play important roles in determining their properties. The interlayer interactions are tunable from noncoupling to strong coupling by controlling the twist angle between adjacent layers. However, the influence of stacking sequence and individual component thickness on the properties of vdWHs has rarely been explored. In this work, the influence of the stacking sequence of WSe2 and graphene in vdWHs of graphene-on-WSe2 (graphene/WSe2) or WSe2-on-graphene (WSe2/graphene), as well as their thickness, on their interlayer interaction was systematically investigated by ultralow-frequency (ULF) Raman spectroscopy. A series of ULF breathing modes of WSe2 nanosheets in these vdWHs were observed with frequencies highly dependent on graphene thickness. Interestingly, the ULF breathing modes of WSe2 red-shifted in graphene/WSe2 and WSe2/graphene configurations, and the amount of shift in the former was much larger than that in the latter. In contrast, no obvious ULF shift was observed by varying the twist angle between WSe2 and graphene. This indicates that the interlayer interaction is more sensitive to the stacking sequence compared with the twist angle. The results provide alternative approaches to modulate the interlayer interaction of vdWHs and, thus, tune their optical and optoelectronic properties.
基金National Natural Science Foundation of China,Grant/Award Number:12372027Natural Science Foundation of Shandong Province of China,Grant/Award Number:ZR2022MA086Basic Scientific Research Expenses of Central Government Universities,Grant/Award Number:23CX03010A。
文摘Hexagonal boron nitride(h‐BN)is a semiconductor material with a wide band gap,holding promising potential for applications in thermal conductivity devices and nanoresonators in the field of microelectronics.Here,molecular dynamics is simulated to investigate the tensile and vibrational behaviors of bilayer h‐BN under five different stacking modes across varying temperatures.The mechanical properties of five different stacking modes of h‐BN at various temperatures are focused on,including Young's modulus,the ultimate stress,and the ultimate strain.Results indicate that bilayer h‐BN nanosheets exhibit anisotropic characteristics,with their tensile properties decreasing as temperature increases.Additionally,we explore the influence of temperature on the natural frequency of bilayer h‐BN under five different stacking modes.These results establish a fundamental understanding of the mechanical and vibrational characteristics of bilayer h‐BN nanosheets under different stacking modes,contributing to their potential applications in advanced nanodevices operating in extremely high‐temperature environments.
