Research On The Energy Transport Process Of Metal Nano-contact

With excellent characteristics,Micro/Nano materials have broad application prospects in aerospace,microelectronics,military and other fields.However,the heat dissipation problem has been restricting the development of micro/nano devices.Therefore,it is necessary to study the metal contact at the micro/nano scale.Especially in micro/nano devices,there are a large number of metal and heterogeneous material contact interfaces,which have a significant impact on the heat dissipation of the device and are worthy of in-depth study.Firstly,the four-probe method is used to obtain the thermal conductivity and electrical conductivity of the polycrystalline platinum nanowires.The results show that the small-angle scattering causes the thermal reflection coefficient to be approximately 20%higher than the electrical reflection coefficient.And the corresponding Lorentz number is reduced by approximately 30%.According to the relationship between grain size and diameter,a theoretical prediction model for calculating the electrical conductivity and thermal conductivity of platinum nanowires/nano thin films is proposed.The proposed model can avoid the need to re-experimentally measure the thermoelectric parameters when changing the platinum nanowire/nano thin film parameters.To explore the impact of Pt/C contacts between the nanowire and the base in the experiment,the first principle calculations and the atomic Green function method are used to simulate and calculate the thermal properties of Pt/Graphene interface.The transmission coefficient converges around 20 THz.It gets the peak of 0.68 at about 15 THz.The corresponding interface thermal conductivity at 300K（6.2 MWm-2K-1）is two orders of magnitude smaller than the boundary thermal conductivity calculated using the diffusion fitting model(170 MWm^-2K^-1).To explore the effect of size on the thermal properties of metal/graphene interface,the same simulation methods described above are used.The transmission coefficient has the rule:the transmission of finite Cu/Graphene interface gets the peak of 0.84 below 2 THz（0.58 for the infinite interface at about 5 THz）.The thermal conductivities of the two interfaces converges near the Debye temperature of Cu（about 343 K）.It is 41.9 MWm^-2K^-1 for the finite interface and it is much large than the result of the infinite interface(17.6 MWm^-2K^-1).