The ultra-low thermal conductivity of roughened silicon nanowires(SiNWs)can not be explained by the classical phonon-surface scattering mechanism.Although there have been several efforts at developing theories of phon...The ultra-low thermal conductivity of roughened silicon nanowires(SiNWs)can not be explained by the classical phonon-surface scattering mechanism.Although there have been several efforts at developing theories of phonon-surface scattering to interpret it,but the underlying reason is still debatable.We consider that the bond order loss and correlative bond hardening on the surface of roughened SiNWs will deeply influence the thermal transport because of their ultra-high surface-to-volume ratio.By combining this mechanism with the phonon Boltzmann transport equation,we explicate that the suppression of high-frequency phonons results in the obvious reduction of thermal conductivity of roughened SiNWs.Moreover,we verify that the roughness amplitude has more remarkable influence on thermal conductivity of SiNWs than the roughness correlation length,and the surface-to-volume ratio is a nearly universal gauge for thermal conductivity of roughened SiNWs.展开更多
Tellurene,probably one of the most promising two-dimensional(2D)system in the thermoelectric materials,displays ultra-low thermal conductivity.However,a linear thickness-dependent thermal conductivity of unique tellur...Tellurene,probably one of the most promising two-dimensional(2D)system in the thermoelectric materials,displays ultra-low thermal conductivity.However,a linear thickness-dependent thermal conductivity of unique tellurium nanoribbons in this study reveals that unprecedently low thermal conductivity can be achieved via well-defined nanostructures of low-dimensional tellurium instead of pursuing dimension-reduced 2D tellurene.For thinnest tellurium nanoribbon with thickness of 144 nm,the thermal conductivity is only∼1.88±0.22 W·m^(−1)·K^(−1) at room temperature.It’s a dramatic decrease(45%),compared with the well-annealed high-purity bulk tellurium.To be more specific,an expected thermal conductivity of tellurium nanoribbons is even lower than that of 2D tellurene,as a result of strong phonon-surface scattering.We have faith in low-dimensional tellurium in which the thermoelectric performance could realize further breakthrough.展开更多
基金the National Natural Science Foundation of China(Grant No.11874145).
文摘The ultra-low thermal conductivity of roughened silicon nanowires(SiNWs)can not be explained by the classical phonon-surface scattering mechanism.Although there have been several efforts at developing theories of phonon-surface scattering to interpret it,but the underlying reason is still debatable.We consider that the bond order loss and correlative bond hardening on the surface of roughened SiNWs will deeply influence the thermal transport because of their ultra-high surface-to-volume ratio.By combining this mechanism with the phonon Boltzmann transport equation,we explicate that the suppression of high-frequency phonons results in the obvious reduction of thermal conductivity of roughened SiNWs.Moreover,we verify that the roughness amplitude has more remarkable influence on thermal conductivity of SiNWs than the roughness correlation length,and the surface-to-volume ratio is a nearly universal gauge for thermal conductivity of roughened SiNWs.
基金The work was supported by the Key-Area Research and Development Program of Guangdong Province(No.2020B010190004)the National Key R&D Program of China(No.2017YFB0406000)+2 种基金the National Natural Science Foundation of China(Nos.11674245,51772219,11890703,and 11935010)the Open Fund of Zhejiang Provincial Key Laboratory of Quantum Technology and Device(No.20190301)the Zhejiang Provincial Natural Science Foundation of China(No.LZ18E030001).
文摘Tellurene,probably one of the most promising two-dimensional(2D)system in the thermoelectric materials,displays ultra-low thermal conductivity.However,a linear thickness-dependent thermal conductivity of unique tellurium nanoribbons in this study reveals that unprecedently low thermal conductivity can be achieved via well-defined nanostructures of low-dimensional tellurium instead of pursuing dimension-reduced 2D tellurene.For thinnest tellurium nanoribbon with thickness of 144 nm,the thermal conductivity is only∼1.88±0.22 W·m^(−1)·K^(−1) at room temperature.It’s a dramatic decrease(45%),compared with the well-annealed high-purity bulk tellurium.To be more specific,an expected thermal conductivity of tellurium nanoribbons is even lower than that of 2D tellurene,as a result of strong phonon-surface scattering.We have faith in low-dimensional tellurium in which the thermoelectric performance could realize further breakthrough.
