Also, SiNWs are regarded to be a good candidate for efficient thermoelectric devices. Experimentally, thermal conductivities of SiNWs with diameters ranging from 22 to 115 nm [1] and from about 15 to 50 nm [2] have recently been measured and showed unusually low thermal transport properties. The measured thermal conductivities show different temperature dependence for different diameters of nanowires due to the confinement effects to nanometer

size. To understand the thermal transport properties of SiNWs less than 100 nm in diameter, we need to BTSA1 datasheet consider the phonon problems from an atomistic point of view. Theoretically, Mingo et al. [3] calculated thermal conductivities of SiNWs with diameters larger than 35 nm, using the phonon dispersion relation from the data of bulk silicon, and showed good agreement with the experiments. This shows that thermal

conductance Selleckchem I-BET151 calculations with the Boltzmann VX-680 solubility dmso transport formula or molecular dynamics calculations are effective at high temperature in diffusive regime. However, for phonon transport at low temperature or with diameters less than 30 nm, the effects of nanometer-scale structures such as confinement and low speed modes on phonon transport become significant [3]. For such regimes, we need the computational approach, taking the quantum effects explicitly into account. These effects for thermal transport can be included when we use the transmission approach, where the Landauer formula [4] or the non-equilibrium Green’s function (NEGF) technique based on the Keldysh’s theory has been widely studied [5]. The NEGF approach has been well established [6, 7] for electron transport and also the formulation is derived for phonon transport [8]. Recently, some theoretical works have been performed based on the atomistic models using the NEGF technique to calculate the thermal conductances of SiNWs [9–11] and carbon nanotubes [12]. In the present work, we treat the thermal conductance of SiNWs in comparison to the diamond nanowires (DNWs) which have the same DCLK1 atomistic configurations but are made

of the different atomic types. Since the bulk diamond has very high thermal conductivity, we expect that DNWs might also have high thermal conductivity. Here we use the NEGF technique with empirical Tersoff-Brenner interatomic potentials for the atomistic calculations of thermal conductance of SiNWs and DNWs. We present thermal conductance of SiNWs with diameters from 1 to 5 nm with and without vacancy defects and DNWs with diameters ranging from 1 to 4 nm without defects. The diameter dependences of thermal conductances of SiNWs and DNWs with no defects are presented for the temperature ranging from 0 to 300 K. We show how the thermal conductances of SiNWs and DNWs change their behaviors as the temperature decreases with their thickness.