Graphene has been recognized as a promising candidate in developing tunable terahertz(THz)functional devices due to its excellent optical and electronic properties,such as high carrier mobility and tunable conductivit...Graphene has been recognized as a promising candidate in developing tunable terahertz(THz)functional devices due to its excellent optical and electronic properties,such as high carrier mobility and tunable conductivity.Here,we review graphene-based THz modulators we have recently developed.First,the optical properties of graphene are discussed.Then,graphene THz modulators realized by different methods,such as gate voltage,optical pump,and nonlinear response of graphene are presented.Finally,challenges and prospective of graphene THz modulators are also discussed.展开更多
Current three-body abrasive wear theories are based on a macroscale abrasive indentation process,and these theories claim that material wear cannot be achieved without damaging the hard mating surface.In this study,th...Current three-body abrasive wear theories are based on a macroscale abrasive indentation process,and these theories claim that material wear cannot be achieved without damaging the hard mating surface.In this study,the process of three-body nano-abrasive wear of a system including a single crystalline silicon substrate,an amorphous silica cluster,and a polyurethane pad,based on a chemical mechanical polishing(CMP)process,is investigated via molecular dynamics simulations.The cluster slid in a suspended state in smooth regions and underwent rolling impact in the asperity regions of the silicon surface,realizing non-damaging monoatomic material removal.This proves that indentation-plowing is not necessary when performing CMP material removal.Therefore,a non-indentation rolling-sliding adhesion theory for three-body nano-abrasive wear between ultrasoft/hard mating surfaces is proposed.This wear theory not only unifies current mainstream CMP material removal theories,but also clarifies that monoatomic material wear without damage can be realized when the indentation depth is less than zero,thereby perfecting the relationship between material wear and surface damage.These results provide new understanding regarding the CMP microscopic material removal mechanism as well as new research avenues for three-body abrasive wear theory at the monoatomic scale.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0701004)the National Natural Science Founda-tion of China(Grant Nos.61675145,61722509,61735012,and 61420106006).
文摘Graphene has been recognized as a promising candidate in developing tunable terahertz(THz)functional devices due to its excellent optical and electronic properties,such as high carrier mobility and tunable conductivity.Here,we review graphene-based THz modulators we have recently developed.First,the optical properties of graphene are discussed.Then,graphene THz modulators realized by different methods,such as gate voltage,optical pump,and nonlinear response of graphene are presented.Finally,challenges and prospective of graphene THz modulators are also discussed.
基金This work was supported by the National Natural Science Foundation of China(Nos.51375291 and 91323302)the Natural Science Foundation of Shanghai(No.19ZR1401500).
文摘Current three-body abrasive wear theories are based on a macroscale abrasive indentation process,and these theories claim that material wear cannot be achieved without damaging the hard mating surface.In this study,the process of three-body nano-abrasive wear of a system including a single crystalline silicon substrate,an amorphous silica cluster,and a polyurethane pad,based on a chemical mechanical polishing(CMP)process,is investigated via molecular dynamics simulations.The cluster slid in a suspended state in smooth regions and underwent rolling impact in the asperity regions of the silicon surface,realizing non-damaging monoatomic material removal.This proves that indentation-plowing is not necessary when performing CMP material removal.Therefore,a non-indentation rolling-sliding adhesion theory for three-body nano-abrasive wear between ultrasoft/hard mating surfaces is proposed.This wear theory not only unifies current mainstream CMP material removal theories,but also clarifies that monoatomic material wear without damage can be realized when the indentation depth is less than zero,thereby perfecting the relationship between material wear and surface damage.These results provide new understanding regarding the CMP microscopic material removal mechanism as well as new research avenues for three-body abrasive wear theory at the monoatomic scale.
