Molecular Dynamics Study Of Heat Transport Characteristics In Nanostructures Based On Gallium Arsenide

The development of nanotechnology makes the number of field effect transistors in chips increase rapidly.The actual production of the field effect transistor has changed from the initial bulk and film to the fin-like structure and the gate-all-around structure.The latter can make the chip accommodate more field effect transistors in unit area.And nanowires or nanoplates in the gate-all-around transistor need to be set as channel structure.Therefore,the thermal transport characteristics of nanowires in nanostructures need to be studied.In this paper,the thermal transport problem based on gallium arsenide（Ga As）nanostructures is studied from the molecular dynamics.The influence of the surface structure on the thermal conductivity of Ga As nanowire,the problem of heat transport on the interface between silicon dioxide（Si O₂）matrix and Ga As nanowires and the heat transport in Ga As nanowire field effect transistors are studied.The surface structure which affects the thermal conductivity of nanowires is studied.The influence of surface roughness on the thermal transport of Ga As nanowires is studied.By setting different roughness,it is found that the phonon resonance caused by rough structure affects the phonon transport in the main body of nanowires.The mismatch of phonon frequency hinders the phonon transmission.The more the rough units,the more the thermal conductivity of nanowires is Small.The influence of nanowire surface on thermal conductivity was studied from the angle of cross-section shape.It was found that the thermal conductivity of nanowires with circular cross-section was larger.The effect of length on the thermal conductivity of rough Ga As nanowires is studied.It is found that the thermal conductivity of rough Ga As nanowires also increases with the increase of length,but the existence of roughness weakens the influence of length on the thermal conductivity of nanowires,and makes the thermal conductivity of nanowires converge with length.The effect of radial scale on the thermal conductivity of Ga As nanowires is studied.It is found that the thermal conductivity of rough and smooth Ga As nanowires increases with the increase of radial scale.The interaction between substrate and nanowires is studied.The influence of relative position and interfacial coupling strength of Si O₂ substrate on thermal conductivity of Ga As nanowires was studied.It was found that the substrate had inhibition on the heat transfer of Ga As nanowires.Under the condition of the substrate whole surrounding nanowires,multiple interfaces affect the heat transport of nanowires,and the thermal conductivity of nanowires was smaller.The higher the interface coupling strength,the higher the inhibition of low frequency phonon in nanowires,the smaller the thermal conductivity of nanowires.The interfacial thermal conductivity between Ga As nanowires and Si O₂ substrate is calculated.It is found that the higher the interfacial coupling strength is,the greater the interfacial thermal conductivity is.The heat transport in Ga As nanowire field effect transistor is studied.It is found that the thermal transport properties of the nanowires as channel have changed greatly in the complex structure of the field effect transistors.Due to the influence of gate medium and gate,the thermal conductivity of the nanowires in the channel layer is hindered,the inelastic scattering of phonon is enhanced,and the heat transmission is more difficult.The interfacial thermal conductivity of the two interfaces in Ga As nanowire field effect transistor is calculated.Due to the existence of gold gate,the interfacial thermal conductivity between Ga As and Si O₂increases.By calculating the temperature and heat flow distribution of field effect transistor,it is found that the heat flux density in the channel part of nanowires is smaller than other parts of the nanowire under axial heat flow and that in radial heat flow,the heat flux density at the four corners of nanowires is smaller.Finally,the spectral energy density shows that the substrate inhibits the thermal conductivity of Ga As nanowires by enhancing phonon scattering in the nanowires.