The excitation and evolution of magnetohydrodynamic density waves are considered in a differentially rotating thin gaseous disk embedded with both an azimuthal magnetic field and a vertical magnetic field perpendicula...The excitation and evolution of magnetohydrodynamic density waves are considered in a differentially rotating thin gaseous disk embedded with both an azimuthal magnetic field and a vertical magnetic field perpendicular to the disk. Our results shows that the effect of isopedic vertical magnetic fields tend to stabilize the fast MHD density waves while slow MHD density waves are not affected by such vertical magnetic fields for either rigid or differential rotation.展开更多
Tunneling field effect transistors（TFETs） based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low...Tunneling field effect transistors（TFETs） based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low power devices. Here,we investigate the TFETs based on two different integration types： in-plane and vertical heterostructures composed of two kinds of layered phosphorous（β-P and δ-P） by ab initio quantum transport simulations. NDR effects have been observed in both in-plane and vertical heterostructures, and the effects become significant with the highest peak-to-valley ratio（PVR）when the intrinsic region length is near zero. Compared with the in-plane TFET based on β-P and δ-P, better performance with a higher on/off current ratio of - 10-6 and a steeper subthreshold swing（SS） of - 23 mV/dec is achieved in the vertical TFET. Such differences in the NDR effects, on/off current ratio and SS are attributed to the distinct interaction nature of theβ-P and δ-P layers in the in-plane and vertical heterostructures.展开更多
文摘The excitation and evolution of magnetohydrodynamic density waves are considered in a differentially rotating thin gaseous disk embedded with both an azimuthal magnetic field and a vertical magnetic field perpendicular to the disk. Our results shows that the effect of isopedic vertical magnetic fields tend to stabilize the fast MHD density waves while slow MHD density waves are not affected by such vertical magnetic fields for either rigid or differential rotation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11604019,61574020,and 61376018)the Ministry of Science and Technology of China(Grant No.2016YFA0301300)+1 种基金the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),Chinathe Fundamental Research Funds for the Central Universities,China(Grant No.2016RCGD22)
文摘Tunneling field effect transistors（TFETs） based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low power devices. Here,we investigate the TFETs based on two different integration types： in-plane and vertical heterostructures composed of two kinds of layered phosphorous（β-P and δ-P） by ab initio quantum transport simulations. NDR effects have been observed in both in-plane and vertical heterostructures, and the effects become significant with the highest peak-to-valley ratio（PVR）when the intrinsic region length is near zero. Compared with the in-plane TFET based on β-P and δ-P, better performance with a higher on/off current ratio of - 10-6 and a steeper subthreshold swing（SS） of - 23 mV/dec is achieved in the vertical TFET. Such differences in the NDR effects, on/off current ratio and SS are attributed to the distinct interaction nature of theβ-P and δ-P layers in the in-plane and vertical heterostructures.
